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qemu/kvm-all.c
aliguori e22a25c936 Guest debugging support for KVM (Jan Kiszka) 
This is a backport of the guest debugging support for the KVM
accelerator that is now part of the KVM tree. It implements the reworked
KVM kernel API for guest debugging (KVM_CAP_SET_GUEST_DEBUG) which is
not yet part of any mainline kernel but will probably be 2.6.30 stuff.
So far supported is x86, but PPC is expected to catch up soon.

Core features are:
 - unlimited soft-breakpoints via code patching
 - hardware-assisted x86 breakpoints and watchpoints

Changes in this version:
 - use generic hook cpu_synchronize_state to transfer registers between
   user space and kvm
 - push kvm_sw_breakpoints into KVMState

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6825 c046a42c-6fe2-441c-8c8c-71466251a162
2009-03-12 20:12:48 +00:00

832 lines
21 KiB
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/*
* QEMU KVM support
*
* Copyright IBM, Corp. 2008
* Red Hat, Inc. 2008
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
* Glauber Costa <gcosta@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <stdarg.h>
#include <linux/kvm.h>
#include "qemu-common.h"
#include "sysemu.h"
#include "gdbstub.h"
#include "kvm.h"
/* KVM uses PAGE_SIZE in it's definition of COALESCED_MMIO_MAX */
#define PAGE_SIZE TARGET_PAGE_SIZE
//#define DEBUG_KVM
#ifdef DEBUG_KVM
#define dprintf(fmt, ...) \
do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
#else
#define dprintf(fmt, ...) \
do { } while (0)
#endif
typedef struct KVMSlot
{
target_phys_addr_t start_addr;
ram_addr_t memory_size;
ram_addr_t phys_offset;
int slot;
int flags;
} KVMSlot;
typedef struct kvm_dirty_log KVMDirtyLog;
int kvm_allowed = 0;
struct KVMState
{
KVMSlot slots[32];
int fd;
int vmfd;
int coalesced_mmio;
#ifdef KVM_CAP_SET_GUEST_DEBUG
struct kvm_sw_breakpoint_head kvm_sw_breakpoints;
#endif
};
static KVMState *kvm_state;
static KVMSlot *kvm_alloc_slot(KVMState *s)
{
int i;
for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
/* KVM private memory slots */
if (i >= 8 && i < 12)
continue;
if (s->slots[i].memory_size == 0)
return &s->slots[i];
}
return NULL;
}
static KVMSlot *kvm_lookup_slot(KVMState *s, target_phys_addr_t start_addr)
{
int i;
for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
KVMSlot *mem = &s->slots[i];
if (start_addr >= mem->start_addr &&
start_addr < (mem->start_addr + mem->memory_size))
return mem;
}
return NULL;
}
static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot)
{
struct kvm_userspace_memory_region mem;
mem.slot = slot->slot;
mem.guest_phys_addr = slot->start_addr;
mem.memory_size = slot->memory_size;
mem.userspace_addr = (unsigned long)phys_ram_base + slot->phys_offset;
mem.flags = slot->flags;
return kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);
}
int kvm_init_vcpu(CPUState *env)
{
KVMState *s = kvm_state;
long mmap_size;
int ret;
dprintf("kvm_init_vcpu\n");
ret = kvm_vm_ioctl(s, KVM_CREATE_VCPU, env->cpu_index);
if (ret < 0) {
dprintf("kvm_create_vcpu failed\n");
goto err;
}
env->kvm_fd = ret;
env->kvm_state = s;
mmap_size = kvm_ioctl(s, KVM_GET_VCPU_MMAP_SIZE, 0);
if (mmap_size < 0) {
dprintf("KVM_GET_VCPU_MMAP_SIZE failed\n");
goto err;
}
env->kvm_run = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED,
env->kvm_fd, 0);
if (env->kvm_run == MAP_FAILED) {
ret = -errno;
dprintf("mmap'ing vcpu state failed\n");
goto err;
}
ret = kvm_arch_init_vcpu(env);
err:
return ret;
}
int kvm_sync_vcpus(void)
{
CPUState *env;
for (env = first_cpu; env != NULL; env = env->next_cpu) {
int ret;
ret = kvm_arch_put_registers(env);
if (ret)
return ret;
}
return 0;
}
/*
* dirty pages logging control
*/
static int kvm_dirty_pages_log_change(target_phys_addr_t phys_addr, target_phys_addr_t end_addr,
unsigned flags,
unsigned mask)
{
KVMState *s = kvm_state;
KVMSlot *mem = kvm_lookup_slot(s, phys_addr);
if (mem == NULL) {
dprintf("invalid parameters %llx-%llx\n", phys_addr, end_addr);
return -EINVAL;
}
flags = (mem->flags & ~mask) | flags;
/* Nothing changed, no need to issue ioctl */
if (flags == mem->flags)
return 0;
mem->flags = flags;
return kvm_set_user_memory_region(s, mem);
}
int kvm_log_start(target_phys_addr_t phys_addr, target_phys_addr_t end_addr)
{
return kvm_dirty_pages_log_change(phys_addr, end_addr,
KVM_MEM_LOG_DIRTY_PAGES,
KVM_MEM_LOG_DIRTY_PAGES);
}
int kvm_log_stop(target_phys_addr_t phys_addr, target_phys_addr_t end_addr)
{
return kvm_dirty_pages_log_change(phys_addr, end_addr,
0,
KVM_MEM_LOG_DIRTY_PAGES);
}
/**
* kvm_physical_sync_dirty_bitmap - Grab dirty bitmap from kernel space
* This function updates qemu's dirty bitmap using cpu_physical_memory_set_dirty().
* This means all bits are set to dirty.
*
* @start_add: start of logged region. This is what we use to search the memslot
* @end_addr: end of logged region.
*/
void kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, target_phys_addr_t end_addr)
{
KVMState *s = kvm_state;
KVMDirtyLog d;
KVMSlot *mem = kvm_lookup_slot(s, start_addr);
unsigned long alloc_size;
ram_addr_t addr;
target_phys_addr_t phys_addr = start_addr;
dprintf("sync addr: %llx into %lx\n", start_addr, mem->phys_offset);
if (mem == NULL) {
fprintf(stderr, "BUG: %s: invalid parameters\n", __func__);
return;
}
alloc_size = mem->memory_size >> TARGET_PAGE_BITS / sizeof(d.dirty_bitmap);
d.dirty_bitmap = qemu_mallocz(alloc_size);
d.slot = mem->slot;
dprintf("slot %d, phys_addr %llx, uaddr: %llx\n",
d.slot, mem->start_addr, mem->phys_offset);
if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
dprintf("ioctl failed %d\n", errno);
goto out;
}
phys_addr = start_addr;
for (addr = mem->phys_offset; phys_addr < end_addr; phys_addr+= TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) {
unsigned long *bitmap = (unsigned long *)d.dirty_bitmap;
unsigned nr = (phys_addr - start_addr) >> TARGET_PAGE_BITS;
unsigned word = nr / (sizeof(*bitmap) * 8);
unsigned bit = nr % (sizeof(*bitmap) * 8);
if ((bitmap[word] >> bit) & 1)
cpu_physical_memory_set_dirty(addr);
}
out:
qemu_free(d.dirty_bitmap);
}
int kvm_coalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)
{
int ret = -ENOSYS;
#ifdef KVM_CAP_COALESCED_MMIO
KVMState *s = kvm_state;
if (s->coalesced_mmio) {
struct kvm_coalesced_mmio_zone zone;
zone.addr = start;
zone.size = size;
ret = kvm_vm_ioctl(s, KVM_REGISTER_COALESCED_MMIO, &zone);
}
#endif
return ret;
}
int kvm_uncoalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)
{
int ret = -ENOSYS;
#ifdef KVM_CAP_COALESCED_MMIO
KVMState *s = kvm_state;
if (s->coalesced_mmio) {
struct kvm_coalesced_mmio_zone zone;
zone.addr = start;
zone.size = size;
ret = kvm_vm_ioctl(s, KVM_UNREGISTER_COALESCED_MMIO, &zone);
}
#endif
return ret;
}
int kvm_init(int smp_cpus)
{
KVMState *s;
int ret;
int i;
if (smp_cpus > 1)
return -EINVAL;
s = qemu_mallocz(sizeof(KVMState));
#ifdef KVM_CAP_SET_GUEST_DEBUG
TAILQ_INIT(&s->kvm_sw_breakpoints);
#endif
for (i = 0; i < ARRAY_SIZE(s->slots); i++)
s->slots[i].slot = i;
s->vmfd = -1;
s->fd = open("/dev/kvm", O_RDWR);
if (s->fd == -1) {
fprintf(stderr, "Could not access KVM kernel module: %m\n");
ret = -errno;
goto err;
}
ret = kvm_ioctl(s, KVM_GET_API_VERSION, 0);
if (ret < KVM_API_VERSION) {
if (ret > 0)
ret = -EINVAL;
fprintf(stderr, "kvm version too old\n");
goto err;
}
if (ret > KVM_API_VERSION) {
ret = -EINVAL;
fprintf(stderr, "kvm version not supported\n");
goto err;
}
s->vmfd = kvm_ioctl(s, KVM_CREATE_VM, 0);
if (s->vmfd < 0)
goto err;
/* initially, KVM allocated its own memory and we had to jump through
* hooks to make phys_ram_base point to this. Modern versions of KVM
* just use a user allocated buffer so we can use phys_ram_base
* unmodified. Make sure we have a sufficiently modern version of KVM.
*/
ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_USER_MEMORY);
if (ret <= 0) {
if (ret == 0)
ret = -EINVAL;
fprintf(stderr, "kvm does not support KVM_CAP_USER_MEMORY\n");
goto err;
}
/* There was a nasty bug in < kvm-80 that prevents memory slots from being
* destroyed properly. Since we rely on this capability, refuse to work
* with any kernel without this capability. */
ret = kvm_ioctl(s, KVM_CHECK_EXTENSION,
KVM_CAP_DESTROY_MEMORY_REGION_WORKS);
if (ret <= 0) {
if (ret == 0)
ret = -EINVAL;
fprintf(stderr,
"KVM kernel module broken (DESTROY_MEMORY_REGION)\n"
"Please upgrade to at least kvm-81.\n");
goto err;
}
s->coalesced_mmio = 0;
#ifdef KVM_CAP_COALESCED_MMIO
ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_COALESCED_MMIO);
if (ret > 0)
s->coalesced_mmio = ret;
#endif
ret = kvm_arch_init(s, smp_cpus);
if (ret < 0)
goto err;
kvm_state = s;
return 0;
err:
if (s) {
if (s->vmfd != -1)
close(s->vmfd);
if (s->fd != -1)
close(s->fd);
}
qemu_free(s);
return ret;
}
static int kvm_handle_io(CPUState *env, uint16_t port, void *data,
int direction, int size, uint32_t count)
{
int i;
uint8_t *ptr = data;
for (i = 0; i < count; i++) {
if (direction == KVM_EXIT_IO_IN) {
switch (size) {
case 1:
stb_p(ptr, cpu_inb(env, port));
break;
case 2:
stw_p(ptr, cpu_inw(env, port));
break;
case 4:
stl_p(ptr, cpu_inl(env, port));
break;
}
} else {
switch (size) {
case 1:
cpu_outb(env, port, ldub_p(ptr));
break;
case 2:
cpu_outw(env, port, lduw_p(ptr));
break;
case 4:
cpu_outl(env, port, ldl_p(ptr));
break;
}
}
ptr += size;
}
return 1;
}
static void kvm_run_coalesced_mmio(CPUState *env, struct kvm_run *run)
{
#ifdef KVM_CAP_COALESCED_MMIO
KVMState *s = kvm_state;
if (s->coalesced_mmio) {
struct kvm_coalesced_mmio_ring *ring;
ring = (void *)run + (s->coalesced_mmio * TARGET_PAGE_SIZE);
while (ring->first != ring->last) {
struct kvm_coalesced_mmio *ent;
ent = &ring->coalesced_mmio[ring->first];
cpu_physical_memory_write(ent->phys_addr, ent->data, ent->len);
/* FIXME smp_wmb() */
ring->first = (ring->first + 1) % KVM_COALESCED_MMIO_MAX;
}
}
#endif
}
int kvm_cpu_exec(CPUState *env)
{
struct kvm_run *run = env->kvm_run;
int ret;
dprintf("kvm_cpu_exec()\n");
do {
kvm_arch_pre_run(env, run);
if (env->exit_request) {
dprintf("interrupt exit requested\n");
ret = 0;
break;
}
ret = kvm_vcpu_ioctl(env, KVM_RUN, 0);
kvm_arch_post_run(env, run);
if (ret == -EINTR || ret == -EAGAIN) {
dprintf("io window exit\n");
ret = 0;
break;
}
if (ret < 0) {
dprintf("kvm run failed %s\n", strerror(-ret));
abort();
}
kvm_run_coalesced_mmio(env, run);
ret = 0; /* exit loop */
switch (run->exit_reason) {
case KVM_EXIT_IO:
dprintf("handle_io\n");
ret = kvm_handle_io(env, run->io.port,
(uint8_t *)run + run->io.data_offset,
run->io.direction,
run->io.size,
run->io.count);
break;
case KVM_EXIT_MMIO:
dprintf("handle_mmio\n");
cpu_physical_memory_rw(run->mmio.phys_addr,
run->mmio.data,
run->mmio.len,
run->mmio.is_write);
ret = 1;
break;
case KVM_EXIT_IRQ_WINDOW_OPEN:
dprintf("irq_window_open\n");
break;
case KVM_EXIT_SHUTDOWN:
dprintf("shutdown\n");
qemu_system_reset_request();
ret = 1;
break;
case KVM_EXIT_UNKNOWN:
dprintf("kvm_exit_unknown\n");
break;
case KVM_EXIT_FAIL_ENTRY:
dprintf("kvm_exit_fail_entry\n");
break;
case KVM_EXIT_EXCEPTION:
dprintf("kvm_exit_exception\n");
break;
case KVM_EXIT_DEBUG:
dprintf("kvm_exit_debug\n");
#ifdef KVM_CAP_SET_GUEST_DEBUG
if (kvm_arch_debug(&run->debug.arch)) {
gdb_set_stop_cpu(env);
vm_stop(EXCP_DEBUG);
env->exception_index = EXCP_DEBUG;
return 0;
}
/* re-enter, this exception was guest-internal */
ret = 1;
#endif /* KVM_CAP_SET_GUEST_DEBUG */
break;
default:
dprintf("kvm_arch_handle_exit\n");
ret = kvm_arch_handle_exit(env, run);
break;
}
} while (ret > 0);
if (env->exit_request) {
env->exit_request = 0;
env->exception_index = EXCP_INTERRUPT;
}
return ret;
}
void kvm_set_phys_mem(target_phys_addr_t start_addr,
ram_addr_t size,
ram_addr_t phys_offset)
{
KVMState *s = kvm_state;
ram_addr_t flags = phys_offset & ~TARGET_PAGE_MASK;
KVMSlot *mem;
/* KVM does not support read-only slots */
phys_offset &= ~IO_MEM_ROM;
mem = kvm_lookup_slot(s, start_addr);
if (mem) {
if ((flags == IO_MEM_UNASSIGNED) || (flags >= TLB_MMIO)) {
mem->memory_size = 0;
mem->start_addr = start_addr;
mem->phys_offset = 0;
mem->flags = 0;
kvm_set_user_memory_region(s, mem);
} else if (start_addr >= mem->start_addr &&
(start_addr + size) <= (mem->start_addr +
mem->memory_size)) {
KVMSlot slot;
target_phys_addr_t mem_start;
ram_addr_t mem_size, mem_offset;
/* Not splitting */
if ((phys_offset - (start_addr - mem->start_addr)) ==
mem->phys_offset)
return;
/* unregister whole slot */
memcpy(&slot, mem, sizeof(slot));
mem->memory_size = 0;
kvm_set_user_memory_region(s, mem);
/* register prefix slot */
mem_start = slot.start_addr;
mem_size = start_addr - slot.start_addr;
mem_offset = slot.phys_offset;
if (mem_size)
kvm_set_phys_mem(mem_start, mem_size, mem_offset);
/* register new slot */
kvm_set_phys_mem(start_addr, size, phys_offset);
/* register suffix slot */
mem_start = start_addr + size;
mem_offset += mem_size + size;
mem_size = slot.memory_size - mem_size - size;
if (mem_size)
kvm_set_phys_mem(mem_start, mem_size, mem_offset);
return;
} else {
printf("Registering overlapping slot\n");
abort();
}
}
/* KVM does not need to know about this memory */
if (flags >= IO_MEM_UNASSIGNED)
return;
mem = kvm_alloc_slot(s);
mem->memory_size = size;
mem->start_addr = start_addr;
mem->phys_offset = phys_offset;
mem->flags = 0;
kvm_set_user_memory_region(s, mem);
/* FIXME deal with errors */
}
int kvm_ioctl(KVMState *s, int type, ...)
{
int ret;
void *arg;
va_list ap;
va_start(ap, type);
arg = va_arg(ap, void *);
va_end(ap);
ret = ioctl(s->fd, type, arg);
if (ret == -1)
ret = -errno;
return ret;
}
int kvm_vm_ioctl(KVMState *s, int type, ...)
{
int ret;
void *arg;
va_list ap;
va_start(ap, type);
arg = va_arg(ap, void *);
va_end(ap);
ret = ioctl(s->vmfd, type, arg);
if (ret == -1)
ret = -errno;
return ret;
}
int kvm_vcpu_ioctl(CPUState *env, int type, ...)
{
int ret;
void *arg;
va_list ap;
va_start(ap, type);
arg = va_arg(ap, void *);
va_end(ap);
ret = ioctl(env->kvm_fd, type, arg);
if (ret == -1)
ret = -errno;
return ret;
}
int kvm_has_sync_mmu(void)
{
#ifdef KVM_CAP_SYNC_MMU
KVMState *s = kvm_state;
if (kvm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_SYNC_MMU) > 0)
return 1;
#endif
return 0;
}
#ifdef KVM_CAP_SET_GUEST_DEBUG
struct kvm_sw_breakpoint *kvm_find_sw_breakpoint(CPUState *env,
target_ulong pc)
{
struct kvm_sw_breakpoint *bp;
TAILQ_FOREACH(bp, &env->kvm_state->kvm_sw_breakpoints, entry) {
if (bp->pc == pc)
return bp;
}
return NULL;
}
int kvm_sw_breakpoints_active(CPUState *env)
{
return !TAILQ_EMPTY(&env->kvm_state->kvm_sw_breakpoints);
}
int kvm_update_guest_debug(CPUState *env, unsigned long reinject_trap)
{
struct kvm_guest_debug dbg;
dbg.control = 0;
if (env->singlestep_enabled)
dbg.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;
kvm_arch_update_guest_debug(env, &dbg);
dbg.control |= reinject_trap;
return kvm_vcpu_ioctl(env, KVM_SET_GUEST_DEBUG, &dbg);
}
int kvm_insert_breakpoint(CPUState *current_env, target_ulong addr,
target_ulong len, int type)
{
struct kvm_sw_breakpoint *bp;
CPUState *env;
int err;
if (type == GDB_BREAKPOINT_SW) {
bp = kvm_find_sw_breakpoint(current_env, addr);
if (bp) {
bp->use_count++;
return 0;
}
bp = qemu_malloc(sizeof(struct kvm_sw_breakpoint));
if (!bp)
return -ENOMEM;
bp->pc = addr;
bp->use_count = 1;
err = kvm_arch_insert_sw_breakpoint(current_env, bp);
if (err) {
free(bp);
return err;
}
TAILQ_INSERT_HEAD(&current_env->kvm_state->kvm_sw_breakpoints,
bp, entry);
} else {
err = kvm_arch_insert_hw_breakpoint(addr, len, type);
if (err)
return err;
}
for (env = first_cpu; env != NULL; env = env->next_cpu) {
err = kvm_update_guest_debug(env, 0);
if (err)
return err;
}
return 0;
}
int kvm_remove_breakpoint(CPUState *current_env, target_ulong addr,
target_ulong len, int type)
{
struct kvm_sw_breakpoint *bp;
CPUState *env;
int err;
if (type == GDB_BREAKPOINT_SW) {
bp = kvm_find_sw_breakpoint(current_env, addr);
if (!bp)
return -ENOENT;
if (bp->use_count > 1) {
bp->use_count--;
return 0;
}
err = kvm_arch_remove_sw_breakpoint(current_env, bp);
if (err)
return err;
TAILQ_REMOVE(&current_env->kvm_state->kvm_sw_breakpoints, bp, entry);
qemu_free(bp);
} else {
err = kvm_arch_remove_hw_breakpoint(addr, len, type);
if (err)
return err;
}
for (env = first_cpu; env != NULL; env = env->next_cpu) {
err = kvm_update_guest_debug(env, 0);
if (err)
return err;
}
return 0;
}
void kvm_remove_all_breakpoints(CPUState *current_env)
{
struct kvm_sw_breakpoint *bp, *next;
KVMState *s = current_env->kvm_state;
CPUState *env;
TAILQ_FOREACH_SAFE(bp, &s->kvm_sw_breakpoints, entry, next) {
if (kvm_arch_remove_sw_breakpoint(current_env, bp) != 0) {
/* Try harder to find a CPU that currently sees the breakpoint. */
for (env = first_cpu; env != NULL; env = env->next_cpu) {
if (kvm_arch_remove_sw_breakpoint(env, bp) == 0)
break;
}
}
}
kvm_arch_remove_all_hw_breakpoints();
for (env = first_cpu; env != NULL; env = env->next_cpu)
kvm_update_guest_debug(env, 0);
}
#else /* !KVM_CAP_SET_GUEST_DEBUG */
int kvm_update_guest_debug(CPUState *env, unsigned long reinject_trap)
{
return -EINVAL;
}
int kvm_insert_breakpoint(CPUState *current_env, target_ulong addr,
target_ulong len, int type)
{
return -EINVAL;
}
int kvm_remove_breakpoint(CPUState *current_env, target_ulong addr,
target_ulong len, int type)
{
return -EINVAL;
}
void kvm_remove_all_breakpoints(CPUState *current_env)
{
}
#endif /* !KVM_CAP_SET_GUEST_DEBUG */
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