qemu/accel/tcg/cputlb.c

1267 lines
42 KiB
C
Raw Normal View History

/*
* Common CPU TLB handling
*
* Copyright (c) 2003 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
#include "qemu/main-loop.h"
#include "cpu.h"
#include "exec/exec-all.h"
#include "exec/memory.h"
#include "exec/address-spaces.h"
#include "exec/cpu_ldst.h"
#include "exec/cputlb.h"
#include "exec/memory-internal.h"
#include "exec/ram_addr.h"
#include "tcg/tcg.h"
#include "qemu/error-report.h"
#include "exec/log.h"
#include "exec/helper-proto.h"
#include "qemu/atomic.h"
#include "qemu/atomic128.h"
/* DEBUG defines, enable DEBUG_TLB_LOG to log to the CPU_LOG_MMU target */
/* #define DEBUG_TLB */
/* #define DEBUG_TLB_LOG */
#ifdef DEBUG_TLB
# define DEBUG_TLB_GATE 1
# ifdef DEBUG_TLB_LOG
# define DEBUG_TLB_LOG_GATE 1
# else
# define DEBUG_TLB_LOG_GATE 0
# endif
#else
# define DEBUG_TLB_GATE 0
# define DEBUG_TLB_LOG_GATE 0
#endif
#define tlb_debug(fmt, ...) do { \
if (DEBUG_TLB_LOG_GATE) { \
qemu_log_mask(CPU_LOG_MMU, "%s: " fmt, __func__, \
## __VA_ARGS__); \
} else if (DEBUG_TLB_GATE) { \
fprintf(stderr, "%s: " fmt, __func__, ## __VA_ARGS__); \
} \
} while (0)
#define assert_cpu_is_self(cpu) do { \
if (DEBUG_TLB_GATE) { \
g_assert(!(cpu)->created || qemu_cpu_is_self(cpu)); \
} \
} while (0)
/* run_on_cpu_data.target_ptr should always be big enough for a
* target_ulong even on 32 bit builds */
QEMU_BUILD_BUG_ON(sizeof(target_ulong) > sizeof(run_on_cpu_data));
/* We currently can't handle more than 16 bits in the MMUIDX bitmask.
*/
QEMU_BUILD_BUG_ON(NB_MMU_MODES > 16);
#define ALL_MMUIDX_BITS ((1 << NB_MMU_MODES) - 1)
static inline size_t sizeof_tlb(CPUArchState *env, uintptr_t mmu_idx)
{
return env->tlb_mask[mmu_idx] + (1 << CPU_TLB_ENTRY_BITS);
}
static void tlb_window_reset(CPUTLBWindow *window, int64_t ns,
size_t max_entries)
{
window->begin_ns = ns;
window->max_entries = max_entries;
}
static void tlb_dyn_init(CPUArchState *env)
{
int i;
for (i = 0; i < NB_MMU_MODES; i++) {
CPUTLBDesc *desc = &env->tlb_d[i];
size_t n_entries = 1 << CPU_TLB_DYN_DEFAULT_BITS;
tlb_window_reset(&desc->window, get_clock_realtime(), 0);
desc->n_used_entries = 0;
env->tlb_mask[i] = (n_entries - 1) << CPU_TLB_ENTRY_BITS;
env->tlb_table[i] = g_new(CPUTLBEntry, n_entries);
env->iotlb[i] = g_new(CPUIOTLBEntry, n_entries);
}
}
/**
* tlb_mmu_resize_locked() - perform TLB resize bookkeeping; resize if necessary
* @env: CPU that owns the TLB
* @mmu_idx: MMU index of the TLB
*
* Called with tlb_lock_held.
*
* We have two main constraints when resizing a TLB: (1) we only resize it
* on a TLB flush (otherwise we'd have to take a perf hit by either rehashing
* the array or unnecessarily flushing it), which means we do not control how
* frequently the resizing can occur; (2) we don't have access to the guest's
* future scheduling decisions, and therefore have to decide the magnitude of
* the resize based on past observations.
*
* In general, a memory-hungry process can benefit greatly from an appropriately
* sized TLB, since a guest TLB miss is very expensive. This doesn't mean that
* we just have to make the TLB as large as possible; while an oversized TLB
* results in minimal TLB miss rates, it also takes longer to be flushed
* (flushes can be _very_ frequent), and the reduced locality can also hurt
* performance.
*
* To achieve near-optimal performance for all kinds of workloads, we:
*
* 1. Aggressively increase the size of the TLB when the use rate of the
* TLB being flushed is high, since it is likely that in the near future this
* memory-hungry process will execute again, and its memory hungriness will
* probably be similar.
*
* 2. Slowly reduce the size of the TLB as the use rate declines over a
* reasonably large time window. The rationale is that if in such a time window
* we have not observed a high TLB use rate, it is likely that we won't observe
* it in the near future. In that case, once a time window expires we downsize
* the TLB to match the maximum use rate observed in the window.
*
* 3. Try to keep the maximum use rate in a time window in the 30-70% range,
* since in that range performance is likely near-optimal. Recall that the TLB
* is direct mapped, so we want the use rate to be low (or at least not too
* high), since otherwise we are likely to have a significant amount of
* conflict misses.
*/
static void tlb_mmu_resize_locked(CPUArchState *env, int mmu_idx)
{
CPUTLBDesc *desc = &env->tlb_d[mmu_idx];
size_t old_size = tlb_n_entries(env, mmu_idx);
size_t rate;
size_t new_size = old_size;
int64_t now = get_clock_realtime();
int64_t window_len_ms = 100;
int64_t window_len_ns = window_len_ms * 1000 * 1000;
bool window_expired = now > desc->window.begin_ns + window_len_ns;
if (desc->n_used_entries > desc->window.max_entries) {
desc->window.max_entries = desc->n_used_entries;
}
rate = desc->window.max_entries * 100 / old_size;
if (rate > 70) {
new_size = MIN(old_size << 1, 1 << CPU_TLB_DYN_MAX_BITS);
} else if (rate < 30 && window_expired) {
size_t ceil = pow2ceil(desc->window.max_entries);
size_t expected_rate = desc->window.max_entries * 100 / ceil;
/*
* Avoid undersizing when the max number of entries seen is just below
* a pow2. For instance, if max_entries == 1025, the expected use rate
* would be 1025/2048==50%. However, if max_entries == 1023, we'd get
* 1023/1024==99.9% use rate, so we'd likely end up doubling the size
* later. Thus, make sure that the expected use rate remains below 70%.
* (and since we double the size, that means the lowest rate we'd
* expect to get is 35%, which is still in the 30-70% range where
* we consider that the size is appropriate.)
*/
if (expected_rate > 70) {
ceil *= 2;
}
new_size = MAX(ceil, 1 << CPU_TLB_DYN_MIN_BITS);
}
if (new_size == old_size) {
if (window_expired) {
tlb_window_reset(&desc->window, now, desc->n_used_entries);
}
return;
}
g_free(env->tlb_table[mmu_idx]);
g_free(env->iotlb[mmu_idx]);
tlb_window_reset(&desc->window, now, 0);
/* desc->n_used_entries is cleared by the caller */
env->tlb_mask[mmu_idx] = (new_size - 1) << CPU_TLB_ENTRY_BITS;
env->tlb_table[mmu_idx] = g_try_new(CPUTLBEntry, new_size);
env->iotlb[mmu_idx] = g_try_new(CPUIOTLBEntry, new_size);
/*
* If the allocations fail, try smaller sizes. We just freed some
* memory, so going back to half of new_size has a good chance of working.
* Increased memory pressure elsewhere in the system might cause the
* allocations to fail though, so we progressively reduce the allocation
* size, aborting if we cannot even allocate the smallest TLB we support.
*/
while (env->tlb_table[mmu_idx] == NULL || env->iotlb[mmu_idx] == NULL) {
if (new_size == (1 << CPU_TLB_DYN_MIN_BITS)) {
error_report("%s: %s", __func__, strerror(errno));
abort();
}
new_size = MAX(new_size >> 1, 1 << CPU_TLB_DYN_MIN_BITS);
env->tlb_mask[mmu_idx] = (new_size - 1) << CPU_TLB_ENTRY_BITS;
g_free(env->tlb_table[mmu_idx]);
g_free(env->iotlb[mmu_idx]);
env->tlb_table[mmu_idx] = g_try_new(CPUTLBEntry, new_size);
env->iotlb[mmu_idx] = g_try_new(CPUIOTLBEntry, new_size);
}
}
static inline void tlb_table_flush_by_mmuidx(CPUArchState *env, int mmu_idx)
{
tlb_mmu_resize_locked(env, mmu_idx);
memset(env->tlb_table[mmu_idx], -1, sizeof_tlb(env, mmu_idx));
env->tlb_d[mmu_idx].n_used_entries = 0;
}
static inline void tlb_n_used_entries_inc(CPUArchState *env, uintptr_t mmu_idx)
{
env->tlb_d[mmu_idx].n_used_entries++;
}
static inline void tlb_n_used_entries_dec(CPUArchState *env, uintptr_t mmu_idx)
{
env->tlb_d[mmu_idx].n_used_entries--;
}
void tlb_init(CPUState *cpu)
{
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
CPUArchState *env = cpu->env_ptr;
qemu_spin_init(&env->tlb_c.lock);
/* Ensure that cpu_reset performs a full flush. */
env->tlb_c.dirty = ALL_MMUIDX_BITS;
tlb_dyn_init(env);
}
/* flush_all_helper: run fn across all cpus
*
* If the wait flag is set then the src cpu's helper will be queued as
* "safe" work and the loop exited creating a synchronisation point
* where all queued work will be finished before execution starts
* again.
*/
static void flush_all_helper(CPUState *src, run_on_cpu_func fn,
run_on_cpu_data d)
{
CPUState *cpu;
CPU_FOREACH(cpu) {
if (cpu != src) {
async_run_on_cpu(cpu, fn, d);
}
}
}
void tlb_flush_counts(size_t *pfull, size_t *ppart, size_t *pelide)
{
CPUState *cpu;
size_t full = 0, part = 0, elide = 0;
CPU_FOREACH(cpu) {
CPUArchState *env = cpu->env_ptr;
full += atomic_read(&env->tlb_c.full_flush_count);
part += atomic_read(&env->tlb_c.part_flush_count);
elide += atomic_read(&env->tlb_c.elide_flush_count);
}
*pfull = full;
*ppart = part;
*pelide = elide;
}
static void tlb_flush_one_mmuidx_locked(CPUArchState *env, int mmu_idx)
{
tlb_table_flush_by_mmuidx(env, mmu_idx);
memset(env->tlb_v_table[mmu_idx], -1, sizeof(env->tlb_v_table[0]));
env->tlb_d[mmu_idx].large_page_addr = -1;
env->tlb_d[mmu_idx].large_page_mask = -1;
env->tlb_d[mmu_idx].vindex = 0;
}
static void tlb_flush_by_mmuidx_async_work(CPUState *cpu, run_on_cpu_data data)
{
CPUArchState *env = cpu->env_ptr;
uint16_t asked = data.host_int;
uint16_t all_dirty, work, to_clean;
assert_cpu_is_self(cpu);
tlb_debug("mmu_idx:0x%04" PRIx16 "\n", asked);
qemu_spin_lock(&env->tlb_c.lock);
all_dirty = env->tlb_c.dirty;
to_clean = asked & all_dirty;
all_dirty &= ~to_clean;
env->tlb_c.dirty = all_dirty;
for (work = to_clean; work != 0; work &= work - 1) {
int mmu_idx = ctz32(work);
tlb_flush_one_mmuidx_locked(env, mmu_idx);
}
qemu_spin_unlock(&env->tlb_c.lock);
tcg: consistently access cpu->tb_jmp_cache atomically Some code paths can lead to atomic accesses racing with memset() on cpu->tb_jmp_cache, which can result in torn reads/writes and is undefined behaviour in C11. These torn accesses are unlikely to show up as bugs, but from code inspection they seem possible. For example, tb_phys_invalidate does: /* remove the TB from the hash list */ h = tb_jmp_cache_hash_func(tb->pc); CPU_FOREACH(cpu) { if (atomic_read(&cpu->tb_jmp_cache[h]) == tb) { atomic_set(&cpu->tb_jmp_cache[h], NULL); } } Here atomic_set might race with a concurrent memset (such as the ones scheduled via "unsafe" async work, e.g. tlb_flush_page) and therefore we might end up with a torn pointer (or who knows what, because we are under undefined behaviour). This patch converts parallel accesses to cpu->tb_jmp_cache to use atomic primitives, thereby bringing these accesses back to defined behaviour. The price to pay is to potentially execute more instructions when clearing cpu->tb_jmp_cache, but given how infrequently they happen and the small size of the cache, the performance impact I have measured is within noise range when booting debian-arm. Note that under "safe async" work (e.g. do_tb_flush) we could use memset because no other vcpus are running. However I'm keeping these accesses atomic as well to keep things simple and to avoid confusing analysis tools such as ThreadSanitizer. Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <1497486973-25845-1-git-send-email-cota@braap.org> Signed-off-by: Richard Henderson <rth@twiddle.net>
2017-06-15 03:36:13 +03:00
cpu_tb_jmp_cache_clear(cpu);
if (to_clean == ALL_MMUIDX_BITS) {
atomic_set(&env->tlb_c.full_flush_count,
env->tlb_c.full_flush_count + 1);
} else {
atomic_set(&env->tlb_c.part_flush_count,
env->tlb_c.part_flush_count + ctpop16(to_clean));
if (to_clean != asked) {
atomic_set(&env->tlb_c.elide_flush_count,
env->tlb_c.elide_flush_count +
ctpop16(asked & ~to_clean));
}
}
}
void tlb_flush_by_mmuidx(CPUState *cpu, uint16_t idxmap)
{
tlb_debug("mmu_idx: 0x%" PRIx16 "\n", idxmap);
if (cpu->created && !qemu_cpu_is_self(cpu)) {
async_run_on_cpu(cpu, tlb_flush_by_mmuidx_async_work,
RUN_ON_CPU_HOST_INT(idxmap));
} else {
tlb_flush_by_mmuidx_async_work(cpu, RUN_ON_CPU_HOST_INT(idxmap));
}
}
void tlb_flush(CPUState *cpu)
{
tlb_flush_by_mmuidx(cpu, ALL_MMUIDX_BITS);
}
void tlb_flush_by_mmuidx_all_cpus(CPUState *src_cpu, uint16_t idxmap)
{
const run_on_cpu_func fn = tlb_flush_by_mmuidx_async_work;
tlb_debug("mmu_idx: 0x%"PRIx16"\n", idxmap);
flush_all_helper(src_cpu, fn, RUN_ON_CPU_HOST_INT(idxmap));
fn(src_cpu, RUN_ON_CPU_HOST_INT(idxmap));
}
void tlb_flush_all_cpus(CPUState *src_cpu)
{
tlb_flush_by_mmuidx_all_cpus(src_cpu, ALL_MMUIDX_BITS);
}
void tlb_flush_by_mmuidx_all_cpus_synced(CPUState *src_cpu, uint16_t idxmap)
{
const run_on_cpu_func fn = tlb_flush_by_mmuidx_async_work;
tlb_debug("mmu_idx: 0x%"PRIx16"\n", idxmap);
flush_all_helper(src_cpu, fn, RUN_ON_CPU_HOST_INT(idxmap));
async_safe_run_on_cpu(src_cpu, fn, RUN_ON_CPU_HOST_INT(idxmap));
}
void tlb_flush_all_cpus_synced(CPUState *src_cpu)
{
tlb_flush_by_mmuidx_all_cpus_synced(src_cpu, ALL_MMUIDX_BITS);
}
static inline bool tlb_hit_page_anyprot(CPUTLBEntry *tlb_entry,
target_ulong page)
{
return tlb_hit_page(tlb_entry->addr_read, page) ||
cputlb: read CPUTLBEntry.addr_write atomically Updates can come from other threads, so readers that do not take tlb_lock must use atomic_read to avoid undefined behaviour (UB). This completes the conversion to tlb_lock. This conversion results on average in no performance loss, as the following experiments (run on an Intel i7-6700K CPU @ 4.00GHz) show. 1. aarch64 bootup+shutdown test: - Before: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7487.087786 task-clock (msec) # 0.998 CPUs utilized ( +- 0.12% ) 31,574,905,303 cycles # 4.217 GHz ( +- 0.12% ) 57,097,908,812 instructions # 1.81 insns per cycle ( +- 0.08% ) 10,255,415,367 branches # 1369.747 M/sec ( +- 0.08% ) 173,278,962 branch-misses # 1.69% of all branches ( +- 0.18% ) 7.504481349 seconds time elapsed ( +- 0.14% ) - After: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7462.441328 task-clock (msec) # 0.998 CPUs utilized ( +- 0.07% ) 31,478,476,520 cycles # 4.218 GHz ( +- 0.07% ) 57,017,330,084 instructions # 1.81 insns per cycle ( +- 0.05% ) 10,251,929,667 branches # 1373.804 M/sec ( +- 0.05% ) 173,023,787 branch-misses # 1.69% of all branches ( +- 0.11% ) 7.474970463 seconds time elapsed ( +- 0.07% ) 2. SPEC06int: SPEC06int (test set) [Y axis: Speedup over master] 1.15 +-+----+------+------+------+------+------+-------+------+------+------+------+------+------+----+-+ | | 1.1 +-+.................................+++.............................+ tlb-lock-v2 (m+++x) +-+ | +++ | +++ tlb-lock-v3 (spinl|ck) | | +++ | | +++ +++ | | | 1.05 +-+....+++...........####.........|####.+++.|......|.....###....+++...........+++....###.........+-+ | ### ++#| # |# |# ***### +++### +++#+# | +++ | #|# ### | 1 +-+++***+#++++####+++#++#++++++++++#++#+*+*++#++++#+#+****+#++++###++++###++++###++++#+#++++#+#+++-+ | *+* # #++# *** # #### *** # * *++# ****+# *| * # ****|# |# # #|# #+# # # | 0.95 +-+..*.*.#....#..#.*|*..#...#..#.*|*..#.*.*..#.*|.*.#.*++*.#.*++*+#.****.#....#+#....#.#..++#.#..+-+ | * * # # # *|* # # # *|* # * * # *++* # * * # * * # * |* # ++# # # # *** # | | * * # ++# # *+* # # # *|* # * * # * * # * * # * * # *++* # **** # ++# # * * # | 0.9 +-+..*.*.#...|#..#.*.*..#.++#..#.*|*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*.|*.#...|#.#..*.*.#..+-+ | * * # *** # * * # |# # *+* # * * # * * # * * # * * # * * # *++* # |# # * * # | 0.85 +-+..*.*.#..*|*..#.*.*..#.***..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.****.#..*.*.#..+-+ | * * # *+* # * * # *|* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | | * * # * * # * * # *+* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | 0.8 +-+..*.*.#..*.*..#.*.*..#.*.*..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.*++*.#..*.*.#..+-+ | * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # | 0.75 +-+--***##--***###-***###-***###-***###-***###-****##-****##-****##-****##-****##-****##--***##--+-+ 400.perlben401.bzip2403.gcc429.m445.gob456.hmme45462.libqua464.h26471.omnet473483.xalancbmkgeomean png: https://imgur.com/a/BHzpPTW Notes: - tlb-lock-v2 corresponds to an implementation with a mutex. - tlb-lock-v3 corresponds to the current implementation, i.e. a spinlock and a single lock acquisition in tlb_set_page_with_attrs. Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181016153840.25877-1-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-16 18:38:40 +03:00
tlb_hit_page(tlb_addr_write(tlb_entry), page) ||
tlb_hit_page(tlb_entry->addr_code, page);
}
/**
* tlb_entry_is_empty - return true if the entry is not in use
* @te: pointer to CPUTLBEntry
*/
static inline bool tlb_entry_is_empty(const CPUTLBEntry *te)
{
return te->addr_read == -1 && te->addr_write == -1 && te->addr_code == -1;
}
/* Called with tlb_c.lock held */
static inline bool tlb_flush_entry_locked(CPUTLBEntry *tlb_entry,
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
target_ulong page)
{
if (tlb_hit_page_anyprot(tlb_entry, page)) {
memset(tlb_entry, -1, sizeof(*tlb_entry));
return true;
}
return false;
}
/* Called with tlb_c.lock held */
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
static inline void tlb_flush_vtlb_page_locked(CPUArchState *env, int mmu_idx,
target_ulong page)
{
int k;
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
assert_cpu_is_self(ENV_GET_CPU(env));
for (k = 0; k < CPU_VTLB_SIZE; k++) {
if (tlb_flush_entry_locked(&env->tlb_v_table[mmu_idx][k], page)) {
tlb_n_used_entries_dec(env, mmu_idx);
}
}
}
static void tlb_flush_page_locked(CPUArchState *env, int midx,
target_ulong page)
{
target_ulong lp_addr = env->tlb_d[midx].large_page_addr;
target_ulong lp_mask = env->tlb_d[midx].large_page_mask;
/* Check if we need to flush due to large pages. */
if ((page & lp_mask) == lp_addr) {
tlb_debug("forcing full flush midx %d ("
TARGET_FMT_lx "/" TARGET_FMT_lx ")\n",
midx, lp_addr, lp_mask);
tlb_flush_one_mmuidx_locked(env, midx);
} else {
if (tlb_flush_entry_locked(tlb_entry(env, midx, page), page)) {
tlb_n_used_entries_dec(env, midx);
}
tlb_flush_vtlb_page_locked(env, midx, page);
}
}
/* As we are going to hijack the bottom bits of the page address for a
* mmuidx bit mask we need to fail to build if we can't do that
*/
QEMU_BUILD_BUG_ON(NB_MMU_MODES > TARGET_PAGE_BITS_MIN);
static void tlb_flush_page_by_mmuidx_async_work(CPUState *cpu,
run_on_cpu_data data)
{
CPUArchState *env = cpu->env_ptr;
target_ulong addr_and_mmuidx = (target_ulong) data.target_ptr;
target_ulong addr = addr_and_mmuidx & TARGET_PAGE_MASK;
unsigned long mmu_idx_bitmap = addr_and_mmuidx & ALL_MMUIDX_BITS;
int mmu_idx;
assert_cpu_is_self(cpu);
tlb_debug("page addr:" TARGET_FMT_lx " mmu_map:0x%lx\n",
addr, mmu_idx_bitmap);
qemu_spin_lock(&env->tlb_c.lock);
for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
if (test_bit(mmu_idx, &mmu_idx_bitmap)) {
tlb_flush_page_locked(env, mmu_idx, addr);
}
}
qemu_spin_unlock(&env->tlb_c.lock);
tb_flush_jmp_cache(cpu, addr);
}
void tlb_flush_page_by_mmuidx(CPUState *cpu, target_ulong addr, uint16_t idxmap)
{
target_ulong addr_and_mmu_idx;
tlb_debug("addr: "TARGET_FMT_lx" mmu_idx:%" PRIx16 "\n", addr, idxmap);
/* This should already be page aligned */
addr_and_mmu_idx = addr & TARGET_PAGE_MASK;
addr_and_mmu_idx |= idxmap;
if (!qemu_cpu_is_self(cpu)) {
async_run_on_cpu(cpu, tlb_flush_page_by_mmuidx_async_work,
RUN_ON_CPU_TARGET_PTR(addr_and_mmu_idx));
} else {
tlb_flush_page_by_mmuidx_async_work(
cpu, RUN_ON_CPU_TARGET_PTR(addr_and_mmu_idx));
}
}
void tlb_flush_page(CPUState *cpu, target_ulong addr)
{
tlb_flush_page_by_mmuidx(cpu, addr, ALL_MMUIDX_BITS);
}
void tlb_flush_page_by_mmuidx_all_cpus(CPUState *src_cpu, target_ulong addr,
uint16_t idxmap)
{
const run_on_cpu_func fn = tlb_flush_page_by_mmuidx_async_work;
target_ulong addr_and_mmu_idx;
tlb_debug("addr: "TARGET_FMT_lx" mmu_idx:%"PRIx16"\n", addr, idxmap);
/* This should already be page aligned */
addr_and_mmu_idx = addr & TARGET_PAGE_MASK;
addr_and_mmu_idx |= idxmap;
flush_all_helper(src_cpu, fn, RUN_ON_CPU_TARGET_PTR(addr_and_mmu_idx));
fn(src_cpu, RUN_ON_CPU_TARGET_PTR(addr_and_mmu_idx));
}
void tlb_flush_page_all_cpus(CPUState *src, target_ulong addr)
{
tlb_flush_page_by_mmuidx_all_cpus(src, addr, ALL_MMUIDX_BITS);
}
void tlb_flush_page_by_mmuidx_all_cpus_synced(CPUState *src_cpu,
target_ulong addr,
uint16_t idxmap)
{
const run_on_cpu_func fn = tlb_flush_page_by_mmuidx_async_work;
target_ulong addr_and_mmu_idx;
tlb_debug("addr: "TARGET_FMT_lx" mmu_idx:%"PRIx16"\n", addr, idxmap);
/* This should already be page aligned */
addr_and_mmu_idx = addr & TARGET_PAGE_MASK;
addr_and_mmu_idx |= idxmap;
flush_all_helper(src_cpu, fn, RUN_ON_CPU_TARGET_PTR(addr_and_mmu_idx));
async_safe_run_on_cpu(src_cpu, fn, RUN_ON_CPU_TARGET_PTR(addr_and_mmu_idx));
}
void tlb_flush_page_all_cpus_synced(CPUState *src, target_ulong addr)
{
tlb_flush_page_by_mmuidx_all_cpus_synced(src, addr, ALL_MMUIDX_BITS);
}
/* update the TLBs so that writes to code in the virtual page 'addr'
can be detected */
void tlb_protect_code(ram_addr_t ram_addr)
{
cpu_physical_memory_test_and_clear_dirty(ram_addr, TARGET_PAGE_SIZE,
DIRTY_MEMORY_CODE);
}
/* update the TLB so that writes in physical page 'phys_addr' are no longer
tested for self modifying code */
void tlb_unprotect_code(ram_addr_t ram_addr)
{
cpu_physical_memory_set_dirty_flag(ram_addr, DIRTY_MEMORY_CODE);
}
/*
* Dirty write flag handling
*
* When the TCG code writes to a location it looks up the address in
* the TLB and uses that data to compute the final address. If any of
* the lower bits of the address are set then the slow path is forced.
* There are a number of reasons to do this but for normal RAM the
* most usual is detecting writes to code regions which may invalidate
* generated code.
*
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
* Other vCPUs might be reading their TLBs during guest execution, so we update
* te->addr_write with atomic_set. We don't need to worry about this for
* oversized guests as MTTCG is disabled for them.
*
* Called with tlb_c.lock held.
*/
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
static void tlb_reset_dirty_range_locked(CPUTLBEntry *tlb_entry,
uintptr_t start, uintptr_t length)
{
uintptr_t addr = tlb_entry->addr_write;
if ((addr & (TLB_INVALID_MASK | TLB_MMIO | TLB_NOTDIRTY)) == 0) {
addr &= TARGET_PAGE_MASK;
addr += tlb_entry->addend;
if ((addr - start) < length) {
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
#if TCG_OVERSIZED_GUEST
tlb_entry->addr_write |= TLB_NOTDIRTY;
#else
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
atomic_set(&tlb_entry->addr_write,
tlb_entry->addr_write | TLB_NOTDIRTY);
#endif
}
}
}
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
/*
* Called with tlb_c.lock held.
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
* Called only from the vCPU context, i.e. the TLB's owner thread.
*/
static inline void copy_tlb_helper_locked(CPUTLBEntry *d, const CPUTLBEntry *s)
{
*d = *s;
}
/* This is a cross vCPU call (i.e. another vCPU resetting the flags of
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
* the target vCPU).
* We must take tlb_c.lock to avoid racing with another vCPU update. The only
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
* thing actually updated is the target TLB entry ->addr_write flags.
*/
void tlb_reset_dirty(CPUState *cpu, ram_addr_t start1, ram_addr_t length)
{
CPUArchState *env;
int mmu_idx;
env = cpu->env_ptr;
qemu_spin_lock(&env->tlb_c.lock);
for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
unsigned int i;
unsigned int n = tlb_n_entries(env, mmu_idx);
for (i = 0; i < n; i++) {
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
tlb_reset_dirty_range_locked(&env->tlb_table[mmu_idx][i], start1,
length);
}
implementing victim TLB for QEMU system emulated TLB QEMU system mode page table walks are expensive. Taken by running QEMU qemu-system-x86_64 system mode on Intel PIN , a TLB miss and walking a 4-level page tables in guest Linux OS takes ~450 X86 instructions on average. QEMU system mode TLB is implemented using a directly-mapped hashtable. This structure suffers from conflict misses. Increasing the associativity of the TLB may not be the solution to conflict misses as all the ways may have to be walked in serial. A victim TLB is a TLB used to hold translations evicted from the primary TLB upon replacement. The victim TLB lies between the main TLB and its refill path. Victim TLB is of greater associativity (fully associative in this patch). It takes longer to lookup the victim TLB, but its likely better than a full page table walk. The memory translation path is changed as follows : Before Victim TLB: 1. Inline TLB lookup 2. Exit code cache on TLB miss. 3. Check for unaligned, IO accesses 4. TLB refill. 5. Do the memory access. 6. Return to code cache. After Victim TLB: 1. Inline TLB lookup 2. Exit code cache on TLB miss. 3. Check for unaligned, IO accesses 4. Victim TLB lookup. 5. If victim TLB misses, TLB refill 6. Do the memory access. 7. Return to code cache The advantage is that victim TLB can offer more associativity to a directly mapped TLB and thus potentially fewer page table walks while still keeping the time taken to flush within reasonable limits. However, placing a victim TLB before the refill path increase TLB refill path as the victim TLB is consulted before the TLB refill. The performance results demonstrate that the pros outweigh the cons. some performance results taken on SPECINT2006 train datasets and kernel boot and qemu configure script on an Intel(R) Xeon(R) CPU E5620 @ 2.40GHz Linux machine are shown in the Google Doc link below. https://docs.google.com/spreadsheets/d/1eiItzekZwNQOal_h-5iJmC4tMDi051m9qidi5_nwvH4/edit?usp=sharing In summary, victim TLB improves the performance of qemu-system-x86_64 by 11% on average on SPECINT2006, kernelboot and qemu configscript and with highest improvement of in 26% in 456.hmmer. And victim TLB does not result in any performance degradation in any of the measured benchmarks. Furthermore, the implemented victim TLB is architecture independent and is expected to benefit other architectures in QEMU as well. Although there are measurement fluctuations, the performance improvement is very significant and by no means in the range of noises. Signed-off-by: Xin Tong <trent.tong@gmail.com> Message-id: 1407202523-23553-1-git-send-email-trent.tong@gmail.com Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-08-05 05:35:23 +04:00
for (i = 0; i < CPU_VTLB_SIZE; i++) {
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
tlb_reset_dirty_range_locked(&env->tlb_v_table[mmu_idx][i], start1,
length);
}
}
qemu_spin_unlock(&env->tlb_c.lock);
}
/* Called with tlb_c.lock held */
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
static inline void tlb_set_dirty1_locked(CPUTLBEntry *tlb_entry,
target_ulong vaddr)
{
if (tlb_entry->addr_write == (vaddr | TLB_NOTDIRTY)) {
tlb_entry->addr_write = vaddr;
}
}
/* update the TLB corresponding to virtual page vaddr
so that it is no longer dirty */
void tlb_set_dirty(CPUState *cpu, target_ulong vaddr)
{
CPUArchState *env = cpu->env_ptr;
int mmu_idx;
assert_cpu_is_self(cpu);
vaddr &= TARGET_PAGE_MASK;
qemu_spin_lock(&env->tlb_c.lock);
for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
tlb_set_dirty1_locked(tlb_entry(env, mmu_idx, vaddr), vaddr);
}
implementing victim TLB for QEMU system emulated TLB QEMU system mode page table walks are expensive. Taken by running QEMU qemu-system-x86_64 system mode on Intel PIN , a TLB miss and walking a 4-level page tables in guest Linux OS takes ~450 X86 instructions on average. QEMU system mode TLB is implemented using a directly-mapped hashtable. This structure suffers from conflict misses. Increasing the associativity of the TLB may not be the solution to conflict misses as all the ways may have to be walked in serial. A victim TLB is a TLB used to hold translations evicted from the primary TLB upon replacement. The victim TLB lies between the main TLB and its refill path. Victim TLB is of greater associativity (fully associative in this patch). It takes longer to lookup the victim TLB, but its likely better than a full page table walk. The memory translation path is changed as follows : Before Victim TLB: 1. Inline TLB lookup 2. Exit code cache on TLB miss. 3. Check for unaligned, IO accesses 4. TLB refill. 5. Do the memory access. 6. Return to code cache. After Victim TLB: 1. Inline TLB lookup 2. Exit code cache on TLB miss. 3. Check for unaligned, IO accesses 4. Victim TLB lookup. 5. If victim TLB misses, TLB refill 6. Do the memory access. 7. Return to code cache The advantage is that victim TLB can offer more associativity to a directly mapped TLB and thus potentially fewer page table walks while still keeping the time taken to flush within reasonable limits. However, placing a victim TLB before the refill path increase TLB refill path as the victim TLB is consulted before the TLB refill. The performance results demonstrate that the pros outweigh the cons. some performance results taken on SPECINT2006 train datasets and kernel boot and qemu configure script on an Intel(R) Xeon(R) CPU E5620 @ 2.40GHz Linux machine are shown in the Google Doc link below. https://docs.google.com/spreadsheets/d/1eiItzekZwNQOal_h-5iJmC4tMDi051m9qidi5_nwvH4/edit?usp=sharing In summary, victim TLB improves the performance of qemu-system-x86_64 by 11% on average on SPECINT2006, kernelboot and qemu configscript and with highest improvement of in 26% in 456.hmmer. And victim TLB does not result in any performance degradation in any of the measured benchmarks. Furthermore, the implemented victim TLB is architecture independent and is expected to benefit other architectures in QEMU as well. Although there are measurement fluctuations, the performance improvement is very significant and by no means in the range of noises. Signed-off-by: Xin Tong <trent.tong@gmail.com> Message-id: 1407202523-23553-1-git-send-email-trent.tong@gmail.com Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-08-05 05:35:23 +04:00
for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
int k;
for (k = 0; k < CPU_VTLB_SIZE; k++) {
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
tlb_set_dirty1_locked(&env->tlb_v_table[mmu_idx][k], vaddr);
implementing victim TLB for QEMU system emulated TLB QEMU system mode page table walks are expensive. Taken by running QEMU qemu-system-x86_64 system mode on Intel PIN , a TLB miss and walking a 4-level page tables in guest Linux OS takes ~450 X86 instructions on average. QEMU system mode TLB is implemented using a directly-mapped hashtable. This structure suffers from conflict misses. Increasing the associativity of the TLB may not be the solution to conflict misses as all the ways may have to be walked in serial. A victim TLB is a TLB used to hold translations evicted from the primary TLB upon replacement. The victim TLB lies between the main TLB and its refill path. Victim TLB is of greater associativity (fully associative in this patch). It takes longer to lookup the victim TLB, but its likely better than a full page table walk. The memory translation path is changed as follows : Before Victim TLB: 1. Inline TLB lookup 2. Exit code cache on TLB miss. 3. Check for unaligned, IO accesses 4. TLB refill. 5. Do the memory access. 6. Return to code cache. After Victim TLB: 1. Inline TLB lookup 2. Exit code cache on TLB miss. 3. Check for unaligned, IO accesses 4. Victim TLB lookup. 5. If victim TLB misses, TLB refill 6. Do the memory access. 7. Return to code cache The advantage is that victim TLB can offer more associativity to a directly mapped TLB and thus potentially fewer page table walks while still keeping the time taken to flush within reasonable limits. However, placing a victim TLB before the refill path increase TLB refill path as the victim TLB is consulted before the TLB refill. The performance results demonstrate that the pros outweigh the cons. some performance results taken on SPECINT2006 train datasets and kernel boot and qemu configure script on an Intel(R) Xeon(R) CPU E5620 @ 2.40GHz Linux machine are shown in the Google Doc link below. https://docs.google.com/spreadsheets/d/1eiItzekZwNQOal_h-5iJmC4tMDi051m9qidi5_nwvH4/edit?usp=sharing In summary, victim TLB improves the performance of qemu-system-x86_64 by 11% on average on SPECINT2006, kernelboot and qemu configscript and with highest improvement of in 26% in 456.hmmer. And victim TLB does not result in any performance degradation in any of the measured benchmarks. Furthermore, the implemented victim TLB is architecture independent and is expected to benefit other architectures in QEMU as well. Although there are measurement fluctuations, the performance improvement is very significant and by no means in the range of noises. Signed-off-by: Xin Tong <trent.tong@gmail.com> Message-id: 1407202523-23553-1-git-send-email-trent.tong@gmail.com Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-08-05 05:35:23 +04:00
}
}
qemu_spin_unlock(&env->tlb_c.lock);
}
/* Our TLB does not support large pages, so remember the area covered by
large pages and trigger a full TLB flush if these are invalidated. */
static void tlb_add_large_page(CPUArchState *env, int mmu_idx,
target_ulong vaddr, target_ulong size)
{
target_ulong lp_addr = env->tlb_d[mmu_idx].large_page_addr;
target_ulong lp_mask = ~(size - 1);
if (lp_addr == (target_ulong)-1) {
/* No previous large page. */
lp_addr = vaddr;
} else {
/* Extend the existing region to include the new page.
This is a compromise between unnecessary flushes and
the cost of maintaining a full variable size TLB. */
lp_mask &= env->tlb_d[mmu_idx].large_page_mask;
while (((lp_addr ^ vaddr) & lp_mask) != 0) {
lp_mask <<= 1;
}
}
env->tlb_d[mmu_idx].large_page_addr = lp_addr & lp_mask;
env->tlb_d[mmu_idx].large_page_mask = lp_mask;
}
/* Add a new TLB entry. At most one entry for a given virtual address
* is permitted. Only a single TARGET_PAGE_SIZE region is mapped, the
* supplied size is only used by tlb_flush_page.
*
* Called from TCG-generated code, which is under an RCU read-side
* critical section.
*/
void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
hwaddr paddr, MemTxAttrs attrs, int prot,
int mmu_idx, target_ulong size)
{
CPUArchState *env = cpu->env_ptr;
MemoryRegionSection *section;
unsigned int index;
target_ulong address;
target_ulong code_address;
uintptr_t addend;
CPUTLBEntry *te, tn;
hwaddr iotlb, xlat, sz, paddr_page;
target_ulong vaddr_page;
int asidx = cpu_asidx_from_attrs(cpu, attrs);
assert_cpu_is_self(cpu);
if (size <= TARGET_PAGE_SIZE) {
sz = TARGET_PAGE_SIZE;
} else {
tlb_add_large_page(env, mmu_idx, vaddr, size);
sz = size;
}
vaddr_page = vaddr & TARGET_PAGE_MASK;
paddr_page = paddr & TARGET_PAGE_MASK;
section = address_space_translate_for_iotlb(cpu, asidx, paddr_page,
&xlat, &sz, attrs, &prot);
assert(sz >= TARGET_PAGE_SIZE);
tlb_debug("vaddr=" TARGET_FMT_lx " paddr=0x" TARGET_FMT_plx
" prot=%x idx=%d\n",
vaddr, paddr, prot, mmu_idx);
address = vaddr_page;
if (size < TARGET_PAGE_SIZE) {
/*
* Slow-path the TLB entries; we will repeat the MMU check and TLB
* fill on every access.
*/
address |= TLB_RECHECK;
}
if (!memory_region_is_ram(section->mr) &&
!memory_region_is_romd(section->mr)) {
/* IO memory case */
address |= TLB_MMIO;
addend = 0;
} else {
/* TLB_MMIO for rom/romd handled below */
addend = (uintptr_t)memory_region_get_ram_ptr(section->mr) + xlat;
}
code_address = address;
iotlb = memory_region_section_get_iotlb(cpu, section, vaddr_page,
paddr_page, xlat, prot, &address);
index = tlb_index(env, mmu_idx, vaddr_page);
te = tlb_entry(env, mmu_idx, vaddr_page);
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
/*
* Hold the TLB lock for the rest of the function. We could acquire/release
* the lock several times in the function, but it is faster to amortize the
* acquisition cost by acquiring it just once. Note that this leads to
* a longer critical section, but this is not a concern since the TLB lock
* is unlikely to be contended.
*/
qemu_spin_lock(&env->tlb_c.lock);
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
/* Note that the tlb is no longer clean. */
env->tlb_c.dirty |= 1 << mmu_idx;
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
/* Make sure there's no cached translation for the new page. */
tlb_flush_vtlb_page_locked(env, mmu_idx, vaddr_page);
/*
* Only evict the old entry to the victim tlb if it's for a
* different page; otherwise just overwrite the stale data.
*/
if (!tlb_hit_page_anyprot(te, vaddr_page) && !tlb_entry_is_empty(te)) {
unsigned vidx = env->tlb_d[mmu_idx].vindex++ % CPU_VTLB_SIZE;
CPUTLBEntry *tv = &env->tlb_v_table[mmu_idx][vidx];
/* Evict the old entry into the victim tlb. */
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
copy_tlb_helper_locked(tv, te);
env->iotlb_v[mmu_idx][vidx] = env->iotlb[mmu_idx][index];
tlb_n_used_entries_dec(env, mmu_idx);
}
implementing victim TLB for QEMU system emulated TLB QEMU system mode page table walks are expensive. Taken by running QEMU qemu-system-x86_64 system mode on Intel PIN , a TLB miss and walking a 4-level page tables in guest Linux OS takes ~450 X86 instructions on average. QEMU system mode TLB is implemented using a directly-mapped hashtable. This structure suffers from conflict misses. Increasing the associativity of the TLB may not be the solution to conflict misses as all the ways may have to be walked in serial. A victim TLB is a TLB used to hold translations evicted from the primary TLB upon replacement. The victim TLB lies between the main TLB and its refill path. Victim TLB is of greater associativity (fully associative in this patch). It takes longer to lookup the victim TLB, but its likely better than a full page table walk. The memory translation path is changed as follows : Before Victim TLB: 1. Inline TLB lookup 2. Exit code cache on TLB miss. 3. Check for unaligned, IO accesses 4. TLB refill. 5. Do the memory access. 6. Return to code cache. After Victim TLB: 1. Inline TLB lookup 2. Exit code cache on TLB miss. 3. Check for unaligned, IO accesses 4. Victim TLB lookup. 5. If victim TLB misses, TLB refill 6. Do the memory access. 7. Return to code cache The advantage is that victim TLB can offer more associativity to a directly mapped TLB and thus potentially fewer page table walks while still keeping the time taken to flush within reasonable limits. However, placing a victim TLB before the refill path increase TLB refill path as the victim TLB is consulted before the TLB refill. The performance results demonstrate that the pros outweigh the cons. some performance results taken on SPECINT2006 train datasets and kernel boot and qemu configure script on an Intel(R) Xeon(R) CPU E5620 @ 2.40GHz Linux machine are shown in the Google Doc link below. https://docs.google.com/spreadsheets/d/1eiItzekZwNQOal_h-5iJmC4tMDi051m9qidi5_nwvH4/edit?usp=sharing In summary, victim TLB improves the performance of qemu-system-x86_64 by 11% on average on SPECINT2006, kernelboot and qemu configscript and with highest improvement of in 26% in 456.hmmer. And victim TLB does not result in any performance degradation in any of the measured benchmarks. Furthermore, the implemented victim TLB is architecture independent and is expected to benefit other architectures in QEMU as well. Although there are measurement fluctuations, the performance improvement is very significant and by no means in the range of noises. Signed-off-by: Xin Tong <trent.tong@gmail.com> Message-id: 1407202523-23553-1-git-send-email-trent.tong@gmail.com Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-08-05 05:35:23 +04:00
/* refill the tlb */
/*
* At this point iotlb contains a physical section number in the lower
* TARGET_PAGE_BITS, and either
* + the ram_addr_t of the page base of the target RAM (if NOTDIRTY or ROM)
* + the offset within section->mr of the page base (otherwise)
* We subtract the vaddr_page (which is page aligned and thus won't
* disturb the low bits) to give an offset which can be added to the
* (non-page-aligned) vaddr of the eventual memory access to get
* the MemoryRegion offset for the access. Note that the vaddr we
* subtract here is that of the page base, and not the same as the
* vaddr we add back in io_readx()/io_writex()/get_page_addr_code().
*/
env->iotlb[mmu_idx][index].addr = iotlb - vaddr_page;
env->iotlb[mmu_idx][index].attrs = attrs;
/* Now calculate the new entry */
tn.addend = addend - vaddr_page;
if (prot & PAGE_READ) {
tn.addr_read = address;
} else {
tn.addr_read = -1;
}
if (prot & PAGE_EXEC) {
tn.addr_code = code_address;
} else {
tn.addr_code = -1;
}
tn.addr_write = -1;
if (prot & PAGE_WRITE) {
if ((memory_region_is_ram(section->mr) && section->readonly)
|| memory_region_is_romd(section->mr)) {
/* Write access calls the I/O callback. */
tn.addr_write = address | TLB_MMIO;
} else if (memory_region_is_ram(section->mr)
&& cpu_physical_memory_is_clean(
memory_region_get_ram_addr(section->mr) + xlat)) {
tn.addr_write = address | TLB_NOTDIRTY;
} else {
tn.addr_write = address;
}
if (prot & PAGE_WRITE_INV) {
tn.addr_write |= TLB_INVALID_MASK;
}
}
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
copy_tlb_helper_locked(te, &tn);
tlb_n_used_entries_inc(env, mmu_idx);
qemu_spin_unlock(&env->tlb_c.lock);
}
/* Add a new TLB entry, but without specifying the memory
* transaction attributes to be used.
*/
void tlb_set_page(CPUState *cpu, target_ulong vaddr,
hwaddr paddr, int prot,
int mmu_idx, target_ulong size)
{
tlb_set_page_with_attrs(cpu, vaddr, paddr, MEMTXATTRS_UNSPECIFIED,
prot, mmu_idx, size);
}
static inline ram_addr_t qemu_ram_addr_from_host_nofail(void *ptr)
{
ram_addr_t ram_addr;
ram_addr = qemu_ram_addr_from_host(ptr);
if (ram_addr == RAM_ADDR_INVALID) {
error_report("Bad ram pointer %p", ptr);
abort();
}
return ram_addr;
}
static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
int mmu_idx,
target_ulong addr, uintptr_t retaddr,
bool recheck, MMUAccessType access_type, int size)
{
CPUState *cpu = ENV_GET_CPU(env);
hwaddr mr_offset;
MemoryRegionSection *section;
MemoryRegion *mr;
uint64_t val;
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
bool locked = false;
MemTxResult r;
if (recheck) {
/*
* This is a TLB_RECHECK access, where the MMU protection
* covers a smaller range than a target page, and we must
* repeat the MMU check here. This tlb_fill() call might
* longjump out if this access should cause a guest exception.
*/
CPUTLBEntry *entry;
target_ulong tlb_addr;
tlb_fill(cpu, addr, size, MMU_DATA_LOAD, mmu_idx, retaddr);
entry = tlb_entry(env, mmu_idx, addr);
tlb_addr = entry->addr_read;
if (!(tlb_addr & ~(TARGET_PAGE_MASK | TLB_RECHECK))) {
/* RAM access */
uintptr_t haddr = addr + entry->addend;
return ldn_p((void *)haddr, size);
}
/* Fall through for handling IO accesses */
}
section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
mr = section->mr;
mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
cpu->mem_io_pc = retaddr;
if (mr != &io_mem_rom && mr != &io_mem_notdirty && !cpu->can_do_io) {
cpu_io_recompile(cpu, retaddr);
}
cpu->mem_io_vaddr = addr;
cpu->mem_io_access_type = access_type;
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
if (mr->global_locking && !qemu_mutex_iothread_locked()) {
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
qemu_mutex_lock_iothread();
locked = true;
}
r = memory_region_dispatch_read(mr, mr_offset,
&val, size, iotlbentry->attrs);
if (r != MEMTX_OK) {
hwaddr physaddr = mr_offset +
section->offset_within_address_space -
section->offset_within_region;
cpu_transaction_failed(cpu, physaddr, addr, size, access_type,
mmu_idx, iotlbentry->attrs, r, retaddr);
}
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
if (locked) {
qemu_mutex_unlock_iothread();
}
return val;
}
static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
int mmu_idx,
uint64_t val, target_ulong addr,
uintptr_t retaddr, bool recheck, int size)
{
CPUState *cpu = ENV_GET_CPU(env);
hwaddr mr_offset;
MemoryRegionSection *section;
MemoryRegion *mr;
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
bool locked = false;
MemTxResult r;
if (recheck) {
/*
* This is a TLB_RECHECK access, where the MMU protection
* covers a smaller range than a target page, and we must
* repeat the MMU check here. This tlb_fill() call might
* longjump out if this access should cause a guest exception.
*/
CPUTLBEntry *entry;
target_ulong tlb_addr;
tlb_fill(cpu, addr, size, MMU_DATA_STORE, mmu_idx, retaddr);
entry = tlb_entry(env, mmu_idx, addr);
cputlb: read CPUTLBEntry.addr_write atomically Updates can come from other threads, so readers that do not take tlb_lock must use atomic_read to avoid undefined behaviour (UB). This completes the conversion to tlb_lock. This conversion results on average in no performance loss, as the following experiments (run on an Intel i7-6700K CPU @ 4.00GHz) show. 1. aarch64 bootup+shutdown test: - Before: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7487.087786 task-clock (msec) # 0.998 CPUs utilized ( +- 0.12% ) 31,574,905,303 cycles # 4.217 GHz ( +- 0.12% ) 57,097,908,812 instructions # 1.81 insns per cycle ( +- 0.08% ) 10,255,415,367 branches # 1369.747 M/sec ( +- 0.08% ) 173,278,962 branch-misses # 1.69% of all branches ( +- 0.18% ) 7.504481349 seconds time elapsed ( +- 0.14% ) - After: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7462.441328 task-clock (msec) # 0.998 CPUs utilized ( +- 0.07% ) 31,478,476,520 cycles # 4.218 GHz ( +- 0.07% ) 57,017,330,084 instructions # 1.81 insns per cycle ( +- 0.05% ) 10,251,929,667 branches # 1373.804 M/sec ( +- 0.05% ) 173,023,787 branch-misses # 1.69% of all branches ( +- 0.11% ) 7.474970463 seconds time elapsed ( +- 0.07% ) 2. SPEC06int: SPEC06int (test set) [Y axis: Speedup over master] 1.15 +-+----+------+------+------+------+------+-------+------+------+------+------+------+------+----+-+ | | 1.1 +-+.................................+++.............................+ tlb-lock-v2 (m+++x) +-+ | +++ | +++ tlb-lock-v3 (spinl|ck) | | +++ | | +++ +++ | | | 1.05 +-+....+++...........####.........|####.+++.|......|.....###....+++...........+++....###.........+-+ | ### ++#| # |# |# ***### +++### +++#+# | +++ | #|# ### | 1 +-+++***+#++++####+++#++#++++++++++#++#+*+*++#++++#+#+****+#++++###++++###++++###++++#+#++++#+#+++-+ | *+* # #++# *** # #### *** # * *++# ****+# *| * # ****|# |# # #|# #+# # # | 0.95 +-+..*.*.#....#..#.*|*..#...#..#.*|*..#.*.*..#.*|.*.#.*++*.#.*++*+#.****.#....#+#....#.#..++#.#..+-+ | * * # # # *|* # # # *|* # * * # *++* # * * # * * # * |* # ++# # # # *** # | | * * # ++# # *+* # # # *|* # * * # * * # * * # * * # *++* # **** # ++# # * * # | 0.9 +-+..*.*.#...|#..#.*.*..#.++#..#.*|*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*.|*.#...|#.#..*.*.#..+-+ | * * # *** # * * # |# # *+* # * * # * * # * * # * * # * * # *++* # |# # * * # | 0.85 +-+..*.*.#..*|*..#.*.*..#.***..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.****.#..*.*.#..+-+ | * * # *+* # * * # *|* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | | * * # * * # * * # *+* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | 0.8 +-+..*.*.#..*.*..#.*.*..#.*.*..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.*++*.#..*.*.#..+-+ | * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # | 0.75 +-+--***##--***###-***###-***###-***###-***###-****##-****##-****##-****##-****##-****##--***##--+-+ 400.perlben401.bzip2403.gcc429.m445.gob456.hmme45462.libqua464.h26471.omnet473483.xalancbmkgeomean png: https://imgur.com/a/BHzpPTW Notes: - tlb-lock-v2 corresponds to an implementation with a mutex. - tlb-lock-v3 corresponds to the current implementation, i.e. a spinlock and a single lock acquisition in tlb_set_page_with_attrs. Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181016153840.25877-1-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-16 18:38:40 +03:00
tlb_addr = tlb_addr_write(entry);
if (!(tlb_addr & ~(TARGET_PAGE_MASK | TLB_RECHECK))) {
/* RAM access */
uintptr_t haddr = addr + entry->addend;
stn_p((void *)haddr, size, val);
return;
}
/* Fall through for handling IO accesses */
}
section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
mr = section->mr;
mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
if (mr != &io_mem_rom && mr != &io_mem_notdirty && !cpu->can_do_io) {
cpu_io_recompile(cpu, retaddr);
}
cpu->mem_io_vaddr = addr;
cpu->mem_io_pc = retaddr;
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
if (mr->global_locking && !qemu_mutex_iothread_locked()) {
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
qemu_mutex_lock_iothread();
locked = true;
}
r = memory_region_dispatch_write(mr, mr_offset,
val, size, iotlbentry->attrs);
if (r != MEMTX_OK) {
hwaddr physaddr = mr_offset +
section->offset_within_address_space -
section->offset_within_region;
cpu_transaction_failed(cpu, physaddr, addr, size, MMU_DATA_STORE,
mmu_idx, iotlbentry->attrs, r, retaddr);
}
tcg: drop global lock during TCG code execution This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com> [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota <cota@braap.org> [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com> [PM: target-arm changes] Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-23 21:29:11 +03:00
if (locked) {
qemu_mutex_unlock_iothread();
}
}
/* Return true if ADDR is present in the victim tlb, and has been copied
back to the main tlb. */
static bool victim_tlb_hit(CPUArchState *env, size_t mmu_idx, size_t index,
size_t elt_ofs, target_ulong page)
{
size_t vidx;
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
assert_cpu_is_self(ENV_GET_CPU(env));
for (vidx = 0; vidx < CPU_VTLB_SIZE; ++vidx) {
CPUTLBEntry *vtlb = &env->tlb_v_table[mmu_idx][vidx];
cputlb: read CPUTLBEntry.addr_write atomically Updates can come from other threads, so readers that do not take tlb_lock must use atomic_read to avoid undefined behaviour (UB). This completes the conversion to tlb_lock. This conversion results on average in no performance loss, as the following experiments (run on an Intel i7-6700K CPU @ 4.00GHz) show. 1. aarch64 bootup+shutdown test: - Before: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7487.087786 task-clock (msec) # 0.998 CPUs utilized ( +- 0.12% ) 31,574,905,303 cycles # 4.217 GHz ( +- 0.12% ) 57,097,908,812 instructions # 1.81 insns per cycle ( +- 0.08% ) 10,255,415,367 branches # 1369.747 M/sec ( +- 0.08% ) 173,278,962 branch-misses # 1.69% of all branches ( +- 0.18% ) 7.504481349 seconds time elapsed ( +- 0.14% ) - After: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7462.441328 task-clock (msec) # 0.998 CPUs utilized ( +- 0.07% ) 31,478,476,520 cycles # 4.218 GHz ( +- 0.07% ) 57,017,330,084 instructions # 1.81 insns per cycle ( +- 0.05% ) 10,251,929,667 branches # 1373.804 M/sec ( +- 0.05% ) 173,023,787 branch-misses # 1.69% of all branches ( +- 0.11% ) 7.474970463 seconds time elapsed ( +- 0.07% ) 2. SPEC06int: SPEC06int (test set) [Y axis: Speedup over master] 1.15 +-+----+------+------+------+------+------+-------+------+------+------+------+------+------+----+-+ | | 1.1 +-+.................................+++.............................+ tlb-lock-v2 (m+++x) +-+ | +++ | +++ tlb-lock-v3 (spinl|ck) | | +++ | | +++ +++ | | | 1.05 +-+....+++...........####.........|####.+++.|......|.....###....+++...........+++....###.........+-+ | ### ++#| # |# |# ***### +++### +++#+# | +++ | #|# ### | 1 +-+++***+#++++####+++#++#++++++++++#++#+*+*++#++++#+#+****+#++++###++++###++++###++++#+#++++#+#+++-+ | *+* # #++# *** # #### *** # * *++# ****+# *| * # ****|# |# # #|# #+# # # | 0.95 +-+..*.*.#....#..#.*|*..#...#..#.*|*..#.*.*..#.*|.*.#.*++*.#.*++*+#.****.#....#+#....#.#..++#.#..+-+ | * * # # # *|* # # # *|* # * * # *++* # * * # * * # * |* # ++# # # # *** # | | * * # ++# # *+* # # # *|* # * * # * * # * * # * * # *++* # **** # ++# # * * # | 0.9 +-+..*.*.#...|#..#.*.*..#.++#..#.*|*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*.|*.#...|#.#..*.*.#..+-+ | * * # *** # * * # |# # *+* # * * # * * # * * # * * # * * # *++* # |# # * * # | 0.85 +-+..*.*.#..*|*..#.*.*..#.***..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.****.#..*.*.#..+-+ | * * # *+* # * * # *|* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | | * * # * * # * * # *+* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | 0.8 +-+..*.*.#..*.*..#.*.*..#.*.*..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.*++*.#..*.*.#..+-+ | * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # | 0.75 +-+--***##--***###-***###-***###-***###-***###-****##-****##-****##-****##-****##-****##--***##--+-+ 400.perlben401.bzip2403.gcc429.m445.gob456.hmme45462.libqua464.h26471.omnet473483.xalancbmkgeomean png: https://imgur.com/a/BHzpPTW Notes: - tlb-lock-v2 corresponds to an implementation with a mutex. - tlb-lock-v3 corresponds to the current implementation, i.e. a spinlock and a single lock acquisition in tlb_set_page_with_attrs. Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181016153840.25877-1-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-16 18:38:40 +03:00
target_ulong cmp;
/* elt_ofs might correspond to .addr_write, so use atomic_read */
#if TCG_OVERSIZED_GUEST
cmp = *(target_ulong *)((uintptr_t)vtlb + elt_ofs);
#else
cmp = atomic_read((target_ulong *)((uintptr_t)vtlb + elt_ofs));
#endif
if (cmp == page) {
/* Found entry in victim tlb, swap tlb and iotlb. */
CPUTLBEntry tmptlb, *tlb = &env->tlb_table[mmu_idx][index];
qemu_spin_lock(&env->tlb_c.lock);
cputlb: serialize tlb updates with env->tlb_lock Currently we rely on atomic operations for cross-CPU invalidations. There are two cases that these atomics miss: cross-CPU invalidations can race with either (1) vCPU threads flushing their TLB, which happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB, which updates .addr_write with a regular store. This results in undefined behaviour, since we're mixing regular and atomic ops on concurrent accesses. Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table and the corresponding victim cache now hold the lock. The readers that do not hold tlb_lock must use atomic reads when reading .addr_write, since this field can be updated by other threads; the conversion to atomic reads is done in the next patch. Note that an alternative fix would be to expand the use of atomic ops. However, in the case of TLB flushes this would have a huge performance impact, since (1) TLB flushes can happen very frequently and (2) we currently use a full memory barrier to flush each TLB entry, and a TLB has many entries. Instead, acquiring the lock is barely slower than a full memory barrier since it is uncontended, and with a single lock acquisition we can flush the entire TLB. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181009174557.16125-6-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-09 20:45:56 +03:00
copy_tlb_helper_locked(&tmptlb, tlb);
copy_tlb_helper_locked(tlb, vtlb);
copy_tlb_helper_locked(vtlb, &tmptlb);
qemu_spin_unlock(&env->tlb_c.lock);
CPUIOTLBEntry tmpio, *io = &env->iotlb[mmu_idx][index];
CPUIOTLBEntry *vio = &env->iotlb_v[mmu_idx][vidx];
tmpio = *io; *io = *vio; *vio = tmpio;
return true;
}
}
return false;
}
/* Macro to call the above, with local variables from the use context. */
#define VICTIM_TLB_HIT(TY, ADDR) \
victim_tlb_hit(env, mmu_idx, index, offsetof(CPUTLBEntry, TY), \
(ADDR) & TARGET_PAGE_MASK)
/* NOTE: this function can trigger an exception */
/* NOTE2: the returned address is not exactly the physical address: it
* is actually a ram_addr_t (in system mode; the user mode emulation
* version of this function returns a guest virtual address).
*/
tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr)
{
uintptr_t mmu_idx = cpu_mmu_index(env, true);
uintptr_t index = tlb_index(env, mmu_idx, addr);
CPUTLBEntry *entry = tlb_entry(env, mmu_idx, addr);
void *p;
if (unlikely(!tlb_hit(entry->addr_code, addr))) {
if (!VICTIM_TLB_HIT(addr_code, addr)) {
tlb_fill(ENV_GET_CPU(env), addr, 0, MMU_INST_FETCH, mmu_idx, 0);
index = tlb_index(env, mmu_idx, addr);
entry = tlb_entry(env, mmu_idx, addr);
}
assert(tlb_hit(entry->addr_code, addr));
}
if (unlikely(entry->addr_code & (TLB_RECHECK | TLB_MMIO))) {
/*
* Return -1 if we can't translate and execute from an entire
* page of RAM here, which will cause us to execute by loading
* and translating one insn at a time, without caching:
* - TLB_RECHECK: means the MMU protection covers a smaller range
* than a target page, so we must redo the MMU check every insn
* - TLB_MMIO: region is not backed by RAM
*/
return -1;
}
p = (void *)((uintptr_t)addr + entry->addend);
return qemu_ram_addr_from_host_nofail(p);
}
/* Probe for whether the specified guest write access is permitted.
* If it is not permitted then an exception will be taken in the same
* way as if this were a real write access (and we will not return).
* Otherwise the function will return, and there will be a valid
* entry in the TLB for this access.
*/
void probe_write(CPUArchState *env, target_ulong addr, int size, int mmu_idx,
uintptr_t retaddr)
{
uintptr_t index = tlb_index(env, mmu_idx, addr);
CPUTLBEntry *entry = tlb_entry(env, mmu_idx, addr);
cputlb: read CPUTLBEntry.addr_write atomically Updates can come from other threads, so readers that do not take tlb_lock must use atomic_read to avoid undefined behaviour (UB). This completes the conversion to tlb_lock. This conversion results on average in no performance loss, as the following experiments (run on an Intel i7-6700K CPU @ 4.00GHz) show. 1. aarch64 bootup+shutdown test: - Before: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7487.087786 task-clock (msec) # 0.998 CPUs utilized ( +- 0.12% ) 31,574,905,303 cycles # 4.217 GHz ( +- 0.12% ) 57,097,908,812 instructions # 1.81 insns per cycle ( +- 0.08% ) 10,255,415,367 branches # 1369.747 M/sec ( +- 0.08% ) 173,278,962 branch-misses # 1.69% of all branches ( +- 0.18% ) 7.504481349 seconds time elapsed ( +- 0.14% ) - After: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7462.441328 task-clock (msec) # 0.998 CPUs utilized ( +- 0.07% ) 31,478,476,520 cycles # 4.218 GHz ( +- 0.07% ) 57,017,330,084 instructions # 1.81 insns per cycle ( +- 0.05% ) 10,251,929,667 branches # 1373.804 M/sec ( +- 0.05% ) 173,023,787 branch-misses # 1.69% of all branches ( +- 0.11% ) 7.474970463 seconds time elapsed ( +- 0.07% ) 2. SPEC06int: SPEC06int (test set) [Y axis: Speedup over master] 1.15 +-+----+------+------+------+------+------+-------+------+------+------+------+------+------+----+-+ | | 1.1 +-+.................................+++.............................+ tlb-lock-v2 (m+++x) +-+ | +++ | +++ tlb-lock-v3 (spinl|ck) | | +++ | | +++ +++ | | | 1.05 +-+....+++...........####.........|####.+++.|......|.....###....+++...........+++....###.........+-+ | ### ++#| # |# |# ***### +++### +++#+# | +++ | #|# ### | 1 +-+++***+#++++####+++#++#++++++++++#++#+*+*++#++++#+#+****+#++++###++++###++++###++++#+#++++#+#+++-+ | *+* # #++# *** # #### *** # * *++# ****+# *| * # ****|# |# # #|# #+# # # | 0.95 +-+..*.*.#....#..#.*|*..#...#..#.*|*..#.*.*..#.*|.*.#.*++*.#.*++*+#.****.#....#+#....#.#..++#.#..+-+ | * * # # # *|* # # # *|* # * * # *++* # * * # * * # * |* # ++# # # # *** # | | * * # ++# # *+* # # # *|* # * * # * * # * * # * * # *++* # **** # ++# # * * # | 0.9 +-+..*.*.#...|#..#.*.*..#.++#..#.*|*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*.|*.#...|#.#..*.*.#..+-+ | * * # *** # * * # |# # *+* # * * # * * # * * # * * # * * # *++* # |# # * * # | 0.85 +-+..*.*.#..*|*..#.*.*..#.***..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.****.#..*.*.#..+-+ | * * # *+* # * * # *|* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | | * * # * * # * * # *+* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | 0.8 +-+..*.*.#..*.*..#.*.*..#.*.*..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.*++*.#..*.*.#..+-+ | * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # | 0.75 +-+--***##--***###-***###-***###-***###-***###-****##-****##-****##-****##-****##-****##--***##--+-+ 400.perlben401.bzip2403.gcc429.m445.gob456.hmme45462.libqua464.h26471.omnet473483.xalancbmkgeomean png: https://imgur.com/a/BHzpPTW Notes: - tlb-lock-v2 corresponds to an implementation with a mutex. - tlb-lock-v3 corresponds to the current implementation, i.e. a spinlock and a single lock acquisition in tlb_set_page_with_attrs. Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181016153840.25877-1-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-16 18:38:40 +03:00
if (!tlb_hit(tlb_addr_write(entry), addr)) {
/* TLB entry is for a different page */
if (!VICTIM_TLB_HIT(addr_write, addr)) {
tlb_fill(ENV_GET_CPU(env), addr, size, MMU_DATA_STORE,
mmu_idx, retaddr);
}
}
}
/* Probe for a read-modify-write atomic operation. Do not allow unaligned
* operations, or io operations to proceed. Return the host address. */
static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
TCGMemOpIdx oi, uintptr_t retaddr,
NotDirtyInfo *ndi)
{
size_t mmu_idx = get_mmuidx(oi);
uintptr_t index = tlb_index(env, mmu_idx, addr);
CPUTLBEntry *tlbe = tlb_entry(env, mmu_idx, addr);
cputlb: read CPUTLBEntry.addr_write atomically Updates can come from other threads, so readers that do not take tlb_lock must use atomic_read to avoid undefined behaviour (UB). This completes the conversion to tlb_lock. This conversion results on average in no performance loss, as the following experiments (run on an Intel i7-6700K CPU @ 4.00GHz) show. 1. aarch64 bootup+shutdown test: - Before: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7487.087786 task-clock (msec) # 0.998 CPUs utilized ( +- 0.12% ) 31,574,905,303 cycles # 4.217 GHz ( +- 0.12% ) 57,097,908,812 instructions # 1.81 insns per cycle ( +- 0.08% ) 10,255,415,367 branches # 1369.747 M/sec ( +- 0.08% ) 173,278,962 branch-misses # 1.69% of all branches ( +- 0.18% ) 7.504481349 seconds time elapsed ( +- 0.14% ) - After: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7462.441328 task-clock (msec) # 0.998 CPUs utilized ( +- 0.07% ) 31,478,476,520 cycles # 4.218 GHz ( +- 0.07% ) 57,017,330,084 instructions # 1.81 insns per cycle ( +- 0.05% ) 10,251,929,667 branches # 1373.804 M/sec ( +- 0.05% ) 173,023,787 branch-misses # 1.69% of all branches ( +- 0.11% ) 7.474970463 seconds time elapsed ( +- 0.07% ) 2. SPEC06int: SPEC06int (test set) [Y axis: Speedup over master] 1.15 +-+----+------+------+------+------+------+-------+------+------+------+------+------+------+----+-+ | | 1.1 +-+.................................+++.............................+ tlb-lock-v2 (m+++x) +-+ | +++ | +++ tlb-lock-v3 (spinl|ck) | | +++ | | +++ +++ | | | 1.05 +-+....+++...........####.........|####.+++.|......|.....###....+++...........+++....###.........+-+ | ### ++#| # |# |# ***### +++### +++#+# | +++ | #|# ### | 1 +-+++***+#++++####+++#++#++++++++++#++#+*+*++#++++#+#+****+#++++###++++###++++###++++#+#++++#+#+++-+ | *+* # #++# *** # #### *** # * *++# ****+# *| * # ****|# |# # #|# #+# # # | 0.95 +-+..*.*.#....#..#.*|*..#...#..#.*|*..#.*.*..#.*|.*.#.*++*.#.*++*+#.****.#....#+#....#.#..++#.#..+-+ | * * # # # *|* # # # *|* # * * # *++* # * * # * * # * |* # ++# # # # *** # | | * * # ++# # *+* # # # *|* # * * # * * # * * # * * # *++* # **** # ++# # * * # | 0.9 +-+..*.*.#...|#..#.*.*..#.++#..#.*|*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*.|*.#...|#.#..*.*.#..+-+ | * * # *** # * * # |# # *+* # * * # * * # * * # * * # * * # *++* # |# # * * # | 0.85 +-+..*.*.#..*|*..#.*.*..#.***..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.****.#..*.*.#..+-+ | * * # *+* # * * # *|* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | | * * # * * # * * # *+* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | 0.8 +-+..*.*.#..*.*..#.*.*..#.*.*..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.*++*.#..*.*.#..+-+ | * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # | 0.75 +-+--***##--***###-***###-***###-***###-***###-****##-****##-****##-****##-****##-****##--***##--+-+ 400.perlben401.bzip2403.gcc429.m445.gob456.hmme45462.libqua464.h26471.omnet473483.xalancbmkgeomean png: https://imgur.com/a/BHzpPTW Notes: - tlb-lock-v2 corresponds to an implementation with a mutex. - tlb-lock-v3 corresponds to the current implementation, i.e. a spinlock and a single lock acquisition in tlb_set_page_with_attrs. Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181016153840.25877-1-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-16 18:38:40 +03:00
target_ulong tlb_addr = tlb_addr_write(tlbe);
TCGMemOp mop = get_memop(oi);
int a_bits = get_alignment_bits(mop);
int s_bits = mop & MO_SIZE;
void *hostaddr;
/* Adjust the given return address. */
retaddr -= GETPC_ADJ;
/* Enforce guest required alignment. */
if (unlikely(a_bits > 0 && (addr & ((1 << a_bits) - 1)))) {
/* ??? Maybe indicate atomic op to cpu_unaligned_access */
cpu_unaligned_access(ENV_GET_CPU(env), addr, MMU_DATA_STORE,
mmu_idx, retaddr);
}
/* Enforce qemu required alignment. */
if (unlikely(addr & ((1 << s_bits) - 1))) {
/* We get here if guest alignment was not requested,
or was not enforced by cpu_unaligned_access above.
We might widen the access and emulate, but for now
mark an exception and exit the cpu loop. */
goto stop_the_world;
}
/* Check TLB entry and enforce page permissions. */
if (!tlb_hit(tlb_addr, addr)) {
if (!VICTIM_TLB_HIT(addr_write, addr)) {
tlb_fill(ENV_GET_CPU(env), addr, 1 << s_bits, MMU_DATA_STORE,
mmu_idx, retaddr);
index = tlb_index(env, mmu_idx, addr);
tlbe = tlb_entry(env, mmu_idx, addr);
}
cputlb: read CPUTLBEntry.addr_write atomically Updates can come from other threads, so readers that do not take tlb_lock must use atomic_read to avoid undefined behaviour (UB). This completes the conversion to tlb_lock. This conversion results on average in no performance loss, as the following experiments (run on an Intel i7-6700K CPU @ 4.00GHz) show. 1. aarch64 bootup+shutdown test: - Before: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7487.087786 task-clock (msec) # 0.998 CPUs utilized ( +- 0.12% ) 31,574,905,303 cycles # 4.217 GHz ( +- 0.12% ) 57,097,908,812 instructions # 1.81 insns per cycle ( +- 0.08% ) 10,255,415,367 branches # 1369.747 M/sec ( +- 0.08% ) 173,278,962 branch-misses # 1.69% of all branches ( +- 0.18% ) 7.504481349 seconds time elapsed ( +- 0.14% ) - After: Performance counter stats for 'taskset -c 0 ../img/aarch64/die.sh' (10 runs): 7462.441328 task-clock (msec) # 0.998 CPUs utilized ( +- 0.07% ) 31,478,476,520 cycles # 4.218 GHz ( +- 0.07% ) 57,017,330,084 instructions # 1.81 insns per cycle ( +- 0.05% ) 10,251,929,667 branches # 1373.804 M/sec ( +- 0.05% ) 173,023,787 branch-misses # 1.69% of all branches ( +- 0.11% ) 7.474970463 seconds time elapsed ( +- 0.07% ) 2. SPEC06int: SPEC06int (test set) [Y axis: Speedup over master] 1.15 +-+----+------+------+------+------+------+-------+------+------+------+------+------+------+----+-+ | | 1.1 +-+.................................+++.............................+ tlb-lock-v2 (m+++x) +-+ | +++ | +++ tlb-lock-v3 (spinl|ck) | | +++ | | +++ +++ | | | 1.05 +-+....+++...........####.........|####.+++.|......|.....###....+++...........+++....###.........+-+ | ### ++#| # |# |# ***### +++### +++#+# | +++ | #|# ### | 1 +-+++***+#++++####+++#++#++++++++++#++#+*+*++#++++#+#+****+#++++###++++###++++###++++#+#++++#+#+++-+ | *+* # #++# *** # #### *** # * *++# ****+# *| * # ****|# |# # #|# #+# # # | 0.95 +-+..*.*.#....#..#.*|*..#...#..#.*|*..#.*.*..#.*|.*.#.*++*.#.*++*+#.****.#....#+#....#.#..++#.#..+-+ | * * # # # *|* # # # *|* # * * # *++* # * * # * * # * |* # ++# # # # *** # | | * * # ++# # *+* # # # *|* # * * # * * # * * # * * # *++* # **** # ++# # * * # | 0.9 +-+..*.*.#...|#..#.*.*..#.++#..#.*|*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*.|*.#...|#.#..*.*.#..+-+ | * * # *** # * * # |# # *+* # * * # * * # * * # * * # * * # *++* # |# # * * # | 0.85 +-+..*.*.#..*|*..#.*.*..#.***..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.****.#..*.*.#..+-+ | * * # *+* # * * # *|* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | | * * # * * # * * # *+* # * * # * * # * * # * * # * * # * * # * * # * |* # * * # | 0.8 +-+..*.*.#..*.*..#.*.*..#.*.*..#.*.*..#.*.*..#.*..*.#.*..*.#.*..*.#.*..*.#.*..*.#.*++*.#..*.*.#..+-+ | * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # | 0.75 +-+--***##--***###-***###-***###-***###-***###-****##-****##-****##-****##-****##-****##--***##--+-+ 400.perlben401.bzip2403.gcc429.m445.gob456.hmme45462.libqua464.h26471.omnet473483.xalancbmkgeomean png: https://imgur.com/a/BHzpPTW Notes: - tlb-lock-v2 corresponds to an implementation with a mutex. - tlb-lock-v3 corresponds to the current implementation, i.e. a spinlock and a single lock acquisition in tlb_set_page_with_attrs. Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20181016153840.25877-1-cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-16 18:38:40 +03:00
tlb_addr = tlb_addr_write(tlbe) & ~TLB_INVALID_MASK;
}
/* Notice an IO access or a needs-MMU-lookup access */
if (unlikely(tlb_addr & (TLB_MMIO | TLB_RECHECK))) {
/* There's really nothing that can be done to
support this apart from stop-the-world. */
goto stop_the_world;
}
/* Let the guest notice RMW on a write-only page. */
if (unlikely(tlbe->addr_read != (tlb_addr & ~TLB_NOTDIRTY))) {
tlb_fill(ENV_GET_CPU(env), addr, 1 << s_bits, MMU_DATA_LOAD,
mmu_idx, retaddr);
/* Since we don't support reads and writes to different addresses,
and we do have the proper page loaded for write, this shouldn't
ever return. But just in case, handle via stop-the-world. */
goto stop_the_world;
}
hostaddr = (void *)((uintptr_t)addr + tlbe->addend);
ndi->active = false;
if (unlikely(tlb_addr & TLB_NOTDIRTY)) {
ndi->active = true;
memory_notdirty_write_prepare(ndi, ENV_GET_CPU(env), addr,
qemu_ram_addr_from_host_nofail(hostaddr),
1 << s_bits);
}
return hostaddr;
stop_the_world:
cpu_loop_exit_atomic(ENV_GET_CPU(env), retaddr);
}
#ifdef TARGET_WORDS_BIGENDIAN
# define TGT_BE(X) (X)
# define TGT_LE(X) BSWAP(X)
#else
# define TGT_BE(X) BSWAP(X)
# define TGT_LE(X) (X)
#endif
#define MMUSUFFIX _mmu
#define DATA_SIZE 1
#include "softmmu_template.h"
#define DATA_SIZE 2
#include "softmmu_template.h"
#define DATA_SIZE 4
#include "softmmu_template.h"
#define DATA_SIZE 8
#include "softmmu_template.h"
/* First set of helpers allows passing in of OI and RETADDR. This makes
them callable from other helpers. */
#define EXTRA_ARGS , TCGMemOpIdx oi, uintptr_t retaddr
#define ATOMIC_NAME(X) \
HELPER(glue(glue(glue(atomic_ ## X, SUFFIX), END), _mmu))
#define ATOMIC_MMU_DECLS NotDirtyInfo ndi
#define ATOMIC_MMU_LOOKUP atomic_mmu_lookup(env, addr, oi, retaddr, &ndi)
#define ATOMIC_MMU_CLEANUP \
do { \
if (unlikely(ndi.active)) { \
memory_notdirty_write_complete(&ndi); \
} \
} while (0)
#define DATA_SIZE 1
#include "atomic_template.h"
#define DATA_SIZE 2
#include "atomic_template.h"
#define DATA_SIZE 4
#include "atomic_template.h"
#ifdef CONFIG_ATOMIC64
#define DATA_SIZE 8
#include "atomic_template.h"
#endif
#if HAVE_CMPXCHG128 || HAVE_ATOMIC128
#define DATA_SIZE 16
#include "atomic_template.h"
#endif
/* Second set of helpers are directly callable from TCG as helpers. */
#undef EXTRA_ARGS
#undef ATOMIC_NAME
#undef ATOMIC_MMU_LOOKUP
#define EXTRA_ARGS , TCGMemOpIdx oi
#define ATOMIC_NAME(X) HELPER(glue(glue(atomic_ ## X, SUFFIX), END))
#define ATOMIC_MMU_LOOKUP atomic_mmu_lookup(env, addr, oi, GETPC(), &ndi)
#define DATA_SIZE 1
#include "atomic_template.h"
#define DATA_SIZE 2
#include "atomic_template.h"
#define DATA_SIZE 4
#include "atomic_template.h"
#ifdef CONFIG_ATOMIC64
#define DATA_SIZE 8
#include "atomic_template.h"
#endif
/* Code access functions. */
#undef MMUSUFFIX
#define MMUSUFFIX _cmmu
#undef GETPC
#define GETPC() ((uintptr_t)0)
#define SOFTMMU_CODE_ACCESS
#define DATA_SIZE 1
#include "softmmu_template.h"
#define DATA_SIZE 2
#include "softmmu_template.h"
#define DATA_SIZE 4
#include "softmmu_template.h"
#define DATA_SIZE 8
#include "softmmu_template.h"