Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Before moving them all to include/qemu/xxhash.h.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Add a new flag to mark memory region that are used as non-volatile, by
NVDIMM for example. That bit is propagated down to the flat view, and
reflected in HMP info mtree with a "nv-" prefix on the memory type.
This way, guest_phys_blocks_region_add() can skip the NV memory
regions for dumps and TCG memory clear in a following patch.
Cc: dgilbert@redhat.com
Cc: imammedo@redhat.com
Cc: pbonzini@redhat.com
Cc: guangrong.xiao@linux.intel.com
Cc: mst@redhat.com
Cc: xiaoguangrong.eric@gmail.com
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20181003114454.5662-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is essentially redundant with tlb_c.dirty.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Especially for guests with large numbers of tlbs, like ARM or PPC,
we may well not use all of them in between flush operations.
Remember which tlbs have been used since the last flush, and
avoid any useless flushing.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Our only statistic so far was "full" tlb flushes, where all mmu_idx
are flushed at the same time.
Now count "partial" tlb flushes where sets of mmu_idx are flushed,
but the set is not maximal. Account one per mmu_idx flushed, as
that is the unit of work performed.
We don't actually count elided flushes yet, but go ahead and change
the interface presented to the monitor all at once.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The rest of the tlb victim cache is per-tlb,
the next use index should be as well.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The set of large pages in the kernel is probably not the same
as the set of large pages in the application. Forcing one
range to cover both will flush more often than necessary.
This allows tlb_flush_page_async_work to flush just the one
mmu_idx implicated, which in turn allows us to remove
tlb_check_page_and_flush_by_mmuidx_async_work.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Protect it with the tlb_lock instead of using atomics.
The move puts it in or near the same cacheline as the lock;
using the lock means we don't need a second atomic operation
in order to perform the update. Which makes it cheap to also
update pending_flush in tlb_flush_by_mmuidx_async_work.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This is the first of several moves to reduce the size of the
CPU_COMMON_TLB macro and improve some locality of refernce.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(Thank you to Thomas Huth)
v2: fix 32bit build with updated patch (v3) from Philippe Mathieu-Daudé
built in a 32bit debian sid chroot
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Merge remote-tracking branch 'remotes/vivier2/tags/qemu-trivial-for-3.1-pull-request' into staging
QEMU trivial patches collected between June and October 2018
(Thank you to Thomas Huth)
v2: fix 32bit build with updated patch (v3) from Philippe Mathieu-Daudé
built in a 32bit debian sid chroot
# gpg: Signature made Tue 30 Oct 2018 11:23:01 GMT
# gpg: using RSA key F30C38BD3F2FBE3C
# gpg: Good signature from "Laurent Vivier <lvivier@redhat.com>"
# gpg: aka "Laurent Vivier <laurent@vivier.eu>"
# gpg: aka "Laurent Vivier (Red Hat) <lvivier@redhat.com>"
# Primary key fingerprint: CD2F 75DD C8E3 A4DC 2E4F 5173 F30C 38BD 3F2F BE3C
* remotes/vivier2/tags/qemu-trivial-for-3.1-pull-request:
milkymist-minimac2: Use qemu_log_mask(GUEST_ERROR) instead of error_report
ppc: move at24c to its own CONFIG_ symbol
hw/intc/gicv3: Remove useless parenthesis around DIV_ROUND_UP macro
hw/pci-host: Remove useless parenthesis around DIV_ROUND_UP macro
tests/bios-tables-test: Remove an useless cast
xen: Use the PCI_DEVICE macro
qobject: Catch another straggler for use of qdict_put_str()
configure: Support pkg-config for zlib
tests: Fix typos in comments and help message (found by codespell)
cpu.h: fix a typo in comment
linux-user: fix comment s/atomic_write/atomic_set/
qemu-iotests: make 218 executable
scripts/qemu.py: remove trailing quotes on docstring
scripts/decodetree.py: remove unused imports
docs/devel/testing.rst: add missing newlines after code block
qemu-iotests: fix filename containing checks
tests/tcg/README: fix location for lm32 tests
memory.h: fix typos in comments
vga_int: remove unused function protype
configs/alpha: Remove unused CONFIG_PARALLEL_ISA switch
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Add disassembler support for nanoMIPS.
Reviewed-by: Stefan Markovic <smarkovic@wavecomp.com>
Signed-off-by: Matthew Fortune <matthew.fortune@mips.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
We should not load PVM's state directly into SVM, because there maybe some
errors happen when SVM is receving data, which will break SVM.
We need to ensure receving all data before load the state into SVM. We use
an extra memory to cache these data (PVM's ram). The ram cache in secondary side
is initially the same as SVM/PVM's memory. And in the process of checkpoint,
we cache the dirty pages of PVM into this ram cache firstly, so this ram cache
always the same as PVM's memory at every checkpoint, then we flush this cached ram
to SVM after we receive all PVM's state.
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Isolate the computation of an index from an address into a
helper before we change that function.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
[ cota: convert tlb_vaddr_to_host; use atomic_read on addr_write ]
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181009175129.17888-2-cota@braap.org>
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>
Paves the way for the addition of a per-TLB lock.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181009174557.16125-4-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Now that all the users of old_mmio MemoryRegion accessors
have been converted, we can remove the core code support.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180824170422.5783-2-peter.maydell@linaro.org>
Based-on: <20180802174042.29234-1-peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Before this change, memory-backend-file object is valid for Linux hosts
only because hostmem-file.c is compiled only on Linux hosts.
However, other POSIX-based hosts (such as macOS) can support
memory-backend-file object in the same way as on Linux hosts.
This patch makes hostmem-file.c and related functions to be compiled on
all POSIX-based hosts to make available memory-backend-file on them.
Signed-off-by: Hikaru Nishida <hikarupsp@gmail.com>
Message-Id: <20180924123205.29651-1-hikarupsp@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There is no known available OS for ppc around anymore that uses page
sizes below 4k, so it does not make much sense that we keep wasting
our time on building and testing the ppcemb-softmmu target. It has
been deprecated since two releases, and nobody complained, so let's
remove this now.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This includes nvdimm persistence fixes queued before the release.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging
pc: fixes
This includes nvdimm persistence fixes queued before the release.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
# gpg: Signature made Mon 20 Aug 2018 11:38:11 BST
# gpg: using RSA key 281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg: aka "Michael S. Tsirkin <mst@redhat.com>"
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17 0970 C350 3912 AFBE 8E67
# Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA 8A0D 281F 0DB8 D28D 5469
* remotes/mst/tags/for_upstream:
migration/ram: ensure write persistence on loading all data to PMEM.
migration/ram: Add check and info message to nvdimm post copy.
mem/nvdimm: ensure write persistence to PMEM in label emulation
hostmem-file: add the 'pmem' option
configure: add libpmem support
memory, exec: switch file ram allocation functions to 'flags' parameters
memory, exec: Expose all memory block related flags.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Remove the obsolete MMIO request_ptr APIs; they have no
users now.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: KONRAD Frederic <frederic.konrad@adacore.com>
Message-id: 20180817114619.22354-3-peter.maydell@linaro.org
sparc32plus has 64bit long type but only 32bit virtual address space.
For instance, "apt-get upgrade" failed because of a mmap()/msync()
sequence.
mmap() returned 0xff252000 but msync() used g2h(0xffffffffff252000)
to find the host address. The "(target_ulong)" in g2h() doesn't fix the
address because it is 64bit long.
This patch introduces an "abi_ptr" that is set to uint32_t
if the virtual address space is addressed using 32bit in the linux-user
case. It stays set to target_ulong with softmmu case.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20180814171217.14680-1-laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[lv: added "%" in TARGET_ABI_FMT_ptr "%"PRIx64]
We set up TLB entries in tlb_set_page_with_attrs(), where we have
some logic for determining whether the TLB entry is considered
to be RAM-backed, and thus has a valid addend field. When we
look at the TLB entry in get_page_addr_code(), we use different
logic for determining whether to treat the page as RAM-backed
and use the addend field. This is confusing, and in fact buggy,
because the code in tlb_set_page_with_attrs() correctly decides
that rom_device memory regions not in romd mode are not RAM-backed,
but the code in get_page_addr_code() thinks they are RAM-backed.
This typically results in "Bad ram pointer" assertion if the
guest tries to execute from such a memory region.
Fix this by making get_page_addr_code() just look at the
TLB_MMIO bit in the code_address field of the TLB, which
tlb_set_page_with_attrs() sets if and only if the addend
field is not valid for code execution.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180713150945.12348-1-peter.maydell@linaro.org
When QEMU emulates vNVDIMM labels and migrates vNVDIMM devices, it
needs to know whether the backend storage is a real persistent memory,
in order to decide whether special operations should be performed to
ensure the data persistence.
This boolean option 'pmem' allows users to specify whether the backend
storage of memory-backend-file is a real persistent memory. If
'pmem=on', QEMU will set the flag RAM_PMEM in the RAM block of the
corresponding memory region. If 'pmem' is set while lack of libpmem
support, a error is generated.
Signed-off-by: Junyan He <junyan.he@intel.com>
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
As more flag parameters besides the existing 'share' are going to be
added to following functions
memory_region_init_ram_from_file
qemu_ram_alloc_from_fd
qemu_ram_alloc_from_file
let's switch them to use the 'flags' parameters so as to ease future
flag additions.
The existing 'share' flag is converted to the RAM_SHARED bit in ram_flags,
and other flag bits are ignored by above functions right now.
Signed-off-by: Junyan He <junyan.he@intel.com>
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
We need to use these flags in other files rather than just in exec.c,
For example, RAM_SHARED should be used when create a ram block from file.
We expose them the exec/memory.h
Signed-off-by: Junyan He <junyan.he@intel.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The condition to check whether an address has hit against a particular
TLB entry is not completely trivial. We do this in various places, and
in fact in one place (get_page_addr_code()) we have got the condition
wrong. Abstract it out into new tlb_hit() and tlb_hit_page() inline
functions (one for a known-page-aligned address and one for an
arbitrary address), and use them in all the places where we had the
condition correct.
This is a no-behaviour-change patch; we leave fixing the buggy
code in get_page_addr_code() to a subsequent patch.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180629162122.19376-2-peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
There is no need for a stub, since tb_invalidate_phys_addr can be excised
altogether when TCG is disabled. This is a bit cleaner since it avoids
using code that is clearly specific to user-mode emulation (it calls
mmap_lock/unlock) for the !CONFIG_TCG case.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fix the --disable-tcg breakage introduced by 8bca9a03ec:
$ configure --disable-tcg
[...]
$ make -C i386-softmmu exec.o
make: Entering directory 'i386-softmmu'
CC exec.o
In file included from source/qemu/exec.c:62:0:
source/qemu/include/exec/ram_addr.h:96:6: error: conflicting types for ‘tb_invalidate_phys_range’
void tb_invalidate_phys_range(ram_addr_t start, ram_addr_t end);
^~~~~~~~~~~~~~~~~~~~~~~~
In file included from source/qemu/exec.c:24:0:
source/qemu/include/exec/exec-all.h:309:6: note: previous declaration of ‘tb_invalidate_phys_range’ was here
void tb_invalidate_phys_range(target_ulong start, target_ulong end);
^~~~~~~~~~~~~~~~~~~~~~~~
source/qemu/exec.c:1043:6: error: conflicting types for ‘tb_invalidate_phys_addr’
void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr, MemTxAttrs attrs)
^~~~~~~~~~~~~~~~~~~~~~~
In file included from source/qemu/exec.c:24:0:
source/qemu/include/exec/exec-all.h:308:6: note: previous declaration of ‘tb_invalidate_phys_addr’ was here
void tb_invalidate_phys_addr(target_ulong addr);
^~~~~~~~~~~~~~~~~~~~~~~
make: *** [source/qemu/rules.mak:69: exec.o] Error 1
make: Leaving directory 'i386-softmmu'
Tested to build x86_64-softmmu and i386-softmmu targets.
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180629200710.27626-1-f4bug@amsat.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This adds owners/parents (which are the same, just occasionally
owner==NULL) printing for memory regions; a new '-o' flag
enabled new output.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <20180604032511.6980-1-aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Place them in exec.c, exec-all.h and ram_addr.h. This removes
knowledge of translate-all.h (which is an internal header) from
several files outside accel/tcg and removes knowledge of
AddressSpace from translate-all.c (as it only operates on ram_addr_t).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Not needed. Don't expose last_ram_page().
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180620202736.21399-1-david@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
trace_mem_build_info expects a size_shift for its first argument. Fix it.
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-id: 1527028012-21888-2-git-send-email-cota@braap.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Add support for MMU protection regions that are smaller than
TARGET_PAGE_SIZE. We do this by marking the TLB entry for those
pages with a flag TLB_RECHECK. This flag causes us to always
take the slow-path for accesses. In the slow path we can then
special case them to always call tlb_fill() again, so we have
the correct information for the exact address being accessed.
This change allows us to handle reading and writing from small
regions; we cannot deal with execution from the small region.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180620130619.11362-2-peter.maydell@linaro.org
Use mmap_lock in user-mode to protect TCG state and the page descriptors.
In !user-mode, each vCPU has its own TCG state, so no locks needed.
Per-page locks are used to protect the page descriptors.
Per-TB locks are used in both modes to protect TB jumps.
Some notes:
- tb_lock is removed from notdirty_mem_write by passing a
locked page_collection to tb_invalidate_phys_page_fast.
- tcg_tb_lookup/remove/insert/etc have their own internal lock(s),
so there is no need to further serialize access to them.
- do_tb_flush is run in a safe async context, meaning no other
vCPU threads are running. Therefore acquiring mmap_lock there
is just to please tools such as thread sanitizer.
- Not visible in the diff, but tb_invalidate_phys_page already
has an assert_memory_lock.
- cpu_io_recompile is !user-only, so no mmap_lock there.
- Added mmap_unlock()'s before all siglongjmp's that could
be called in user-mode while mmap_lock is held.
+ Added an assert for !have_mmap_lock() after returning from
the longjmp in cpu_exec, just like we do in cpu_exec_step_atomic.
Performance numbers before/after:
Host: AMD Opteron(tm) Processor 6376
ubuntu 17.04 ppc64 bootup+shutdown time
700 +-+--+----+------+------------+-----------+------------*--+-+
| + + + + + *B |
| before ***B*** ** * |
|tb lock removal ###D### *** |
600 +-+ *** +-+
| ** # |
| *B* #D |
| *** * ## |
500 +-+ *** ### +-+
| * *** ### |
| *B* # ## |
| ** * #D# |
400 +-+ ** ## +-+
| ** ### |
| ** ## |
| ** # ## |
300 +-+ * B* #D# +-+
| B *** ### |
| * ** #### |
| * *** ### |
200 +-+ B *B #D# +-+
| #B* * ## # |
| #* ## |
| + D##D# + + + + |
100 +-+--+----+------+------------+-----------+------------+--+-+
1 8 16 Guest CPUs 48 64
png: https://imgur.com/HwmBHXe
debian jessie aarch64 bootup+shutdown time
90 +-+--+-----+-----+------------+------------+------------+--+-+
| + + + + + + |
| before ***B*** B |
80 +tb lock removal ###D### **D +-+
| **### |
| **## |
70 +-+ ** # +-+
| ** ## |
| ** # |
60 +-+ *B ## +-+
| ** ## |
| *** #D |
50 +-+ *** ## +-+
| * ** ### |
| **B* ### |
40 +-+ **** # ## +-+
| **** #D# |
| ***B** ### |
30 +-+ B***B** #### +-+
| B * * # ### |
| B ###D# |
20 +-+ D ##D## +-+
| D# |
| + + + + + + |
10 +-+--+-----+-----+------------+------------+------------+--+-+
1 8 16 Guest CPUs 48 64
png: https://imgur.com/iGpGFtv
The gains are high for 4-8 CPUs. Beyond that point, however, unrelated
lock contention significantly hurts scalability.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This applies to both user-mode and !user-mode emulation.
Instead of relying on a global lock, protect the list of incoming
jumps with tb->jmp_lock. This lock also protects tb->cflags,
so update all tb->cflags readers outside tb->jmp_lock to use
atomic reads via tb_cflags().
In order to find the destination TB (and therefore its jmp_lock)
from the origin TB, we introduce tb->jmp_dest[].
I considered not using a linked list of jumps, which simplifies
code and makes the struct smaller. However, it unnecessarily increases
memory usage, which results in a performance decrease. See for
instance these numbers booting+shutting down debian-arm:
Time (s) Rel. err (%) Abs. err (s) Rel. slowdown (%)
------------------------------------------------------------------------------
before 20.88 0.74 0.154512 0.
after 20.81 0.38 0.079078 -0.33524904
GTree 21.02 0.28 0.058856 0.67049808
GHashTable + xxhash 21.63 1.08 0.233604 3.5919540
Using a hash table or a binary tree to keep track of the jumps
doesn't really pay off, not only due to the increased memory usage,
but also because most TBs have only 0 or 1 jumps to them. The maximum
number of jumps when booting debian-arm that I measured is 35, but
as we can see in the histogram below a TB with that many incoming jumps
is extremely rare; the average TB has 0.80 incoming jumps.
n_jumps: 379208; avg jumps/tb: 0.801099
dist: [0.0,1.0)|▄█▁▁▁▁▁▁▁▁▁▁▁ ▁▁▁▁▁▁ ▁▁▁ ▁▁▁ ▁|[34.0,35.0]
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The appended adds assertions to make sure we do not longjmp with page
locks held. Note that user-mode has nothing to check, since page_locks
are !user-mode only.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Groundwork for supporting parallel TCG generation.
Instead of using a global lock (tb_lock) to protect changes
to pages, use fine-grained, per-page locks in !user-mode.
User-mode stays with mmap_lock.
Sometimes changes need to happen atomically on more than one
page (e.g. when a TB that spans across two pages is
added/invalidated, or when a range of pages is invalidated).
We therefore introduce struct page_collection, which helps
us keep track of a set of pages that have been locked in
the appropriate locking order (i.e. by ascending page index).
This commit first introduces the structs and the function helpers,
to then convert the calling code to use per-page locking. Note
that tb_lock is not removed yet.
While at it, rename tb_alloc_page to tb_page_add, which pairs with
tb_page_remove.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit does several things, but to avoid churn I merged them all
into the same commit. To wit:
- Use uintptr_t instead of TranslationBlock * for the list of TBs in a page.
Just like we did in (c37e6d7e "tcg: Use uintptr_t type for
jmp_list_{next|first} fields of TB"), the rationale is the same: these
are tagged pointers, not pointers. So use a more appropriate type.
- Only check the least significant bit of the tagged pointers. Masking
with 3/~3 is unnecessary and confusing.
- Introduce the TB_FOR_EACH_TAGGED macro, and use it to define
PAGE_FOR_EACH_TB, which improves readability. Note that
TB_FOR_EACH_TAGGED will gain another user in a subsequent patch.
- Update tb_page_remove to use PAGE_FOR_EACH_TB. In case there
is a bug and we attempt to remove a TB that is not in the list, instead
of segfaulting (since the list is NULL-terminated) we will reach
g_assert_not_reached().
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Thereby making it per-TCGContext. Once we remove tb_lock, this will
avoid an atomic increment every time a TB is invalidated.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This paves the way for enabling scalable parallel generation of TCG code.
Instead of tracking TBs with a single binary search tree (BST), use a
BST for each TCG region, protecting it with a lock. This is as scalable
as it gets, since each TCG thread operates on a separate region.
The core of this change is the introduction of struct tcg_region_tree,
which contains a pointer to a GTree and an associated lock to serialize
accesses to it. We then allocate an array of tcg_region_tree's, adding
the appropriate padding to avoid false sharing based on
qemu_dcache_linesize.
Given a tc_ptr, we first find the corresponding region_tree. This
is done by special-casing the first and last regions first, since they
might be of size != region.size; otherwise we just divide the offset
by region.stride. I was worried about this division (several dozen
cycles of latency), but profiling shows that this is not a fast path.
Note that region.stride is not required to be a power of two; it
is only required to be a multiple of the host's page size.
Note that with this design we can also provide consistent snapshots
about all region trees at once; for instance, tcg_tb_foreach
acquires/releases all region_tree locks before/after iterating over them.
For this reason we now drop tb_lock in dump_exec_info().
As an alternative I considered implementing a concurrent BST, but this
can be tricky to get right, offers no consistent snapshots of the BST,
and performance and scalability-wise I don't think it could ever beat
having separate GTrees, given that our workload is insert-mostly (all
concurrent BST designs I've seen focus, understandably, on making
lookups fast, which comes at the expense of convoluted, non-wait-free
insertions/removals).
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
