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  1. 20 1月, 2015 8 次提交
  3. 08 1月, 2015 5 次提交
  5. 03 1月, 2015 1 次提交
  7. 23 12月, 2014 1 次提交
  9. 17 12月, 2014 1 次提交
  11. 16 12月, 2014 3 次提交
  13. 15 12月, 2014 1 次提交
  15. 11 12月, 2014 1 次提交
    • L
      Add the "-semihosting-config" option. · a38bb079
      由 Liviu Ionescu 提交于 
      The usual semihosting behaviour is to process the system calls locally and
return; unfortuantelly the initial implementation dinamically changed the
target to GDB during debug sessions, which, for the usual arm-none-eabi-gdb,
is not implemented. The result was that during debug sessions the semihosting
calls were discarded.

This patch adds a configuration variable and an option to set it on the
command line:

    -semihosting-config [enable=on|off,]target=native|gdb|auto

This option enables semihosting and defines where the semihosting calls will
be addressed, to QEMU ('native') or to GDB ('gdb'). The default is auto, which
means 'gdb' during debug sessions and 'native' otherwise.
Signed-off-by: NLiviu Ionescu <ilg@livius.net>
Message-id: 1416341957-9796-1-git-send-email-ilg@livius.net
[PMM: moved declaration and definition of semihosting_target to
 gdbstub.h and gdbstub.c to fix build failure on linux-user]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
      a38bb079
  17. 23 11月, 2014 1 次提交
  19. 18 11月, 2014 1 次提交
    • P
      exec: Handle multipage ranges in invalidate_and_set_dirty() · f874bf90
      由 Peter Maydell 提交于 
      The code in invalidate_and_set_dirty() needs to handle addr/length
combinations which cross guest physical page boundaries. This can happen,
for example, when disk I/O reads large blocks into guest RAM which previously
held code that we have cached translations for. Unfortunately we were only
checking the clean/dirty status of the first page in the range, and then
were calling a tb_invalidate function which only handles ranges that don't
cross page boundaries. Fix the function to deal with multipage ranges.

The symptoms of this bug were that guest code would misbehave (eg segfault),
in particular after a guest reboot but potentially any time the guest
reused a page of its physical RAM for new code.

Cc: qemu-stable@nongnu.org
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1416167061-13203-1-git-send-email-peter.maydell@linaro.org
      f874bf90
  21. 03 11月, 2014 1 次提交
  23. 31 10月, 2014 1 次提交
  25. 07 10月, 2014 1 次提交
  27. 12 9月, 2014 1 次提交
  29. 09 9月, 2014 3 次提交
  31. 02 9月, 2014 1 次提交
    • X
      implementing victim TLB for QEMU system emulated TLB · 88e89a57
      由 Xin Tong 提交于 
      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: NXin Tong <trent.tong@gmail.com>
Message-id: 1407202523-23553-1-git-send-email-trent.tong@gmail.com
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
      88e89a57
  33. 29 8月, 2014 1 次提交
  35. 22 8月, 2014 1 次提交
  37. 20 8月, 2014 1 次提交
  39. 18 8月, 2014 3 次提交
  41. 12 8月, 2014 1 次提交
  43. 22 7月, 2014 1 次提交
    • P
      exec: fix migration with devices that use address_space_rw · 6886867e
      由 Paolo Bonzini 提交于 
      Devices that use address_space_rw to write large areas to memory
(as opposed to address_space_map/unmap) were broken with respect
to migration since fe680d0d (exec: Limit translation limiting in
address_space_translate to xen, 2014-05-07).  Such devices include
IDE CD-ROMs.

The reason is that invalidate_and_set_dirty (called by address_space_rw
but not address_space_map/unmap) was only setting the dirty bit for
the first page in the translation.

To fix this, introduce cpu_physical_memory_set_dirty_range_nocode that
is the same as cpu_physical_memory_set_dirty_range except it does not
muck with the DIRTY_MEMORY_CODE bitmap.  This function can be used if
the caller invalidates translations with tb_invalidate_phys_page_range.

There is another difference between cpu_physical_memory_set_dirty_range
and cpu_physical_memory_set_dirty_flag; the former includes a call
to xen_modified_memory.  This is handled separately in
invalidate_and_set_dirty, and is not needed in other callers of
cpu_physical_memory_set_dirty_range_nocode, so leave it alone.

Just one nit: now that invalidate_and_set_dirty takes care of handling
multiple pages, there is no need for address_space_unmap to wrap it
in a loop.  In fact that loop would now be O(n^2).
Reported-by: NDave Gilbert <dgilbert@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Tested-by: NGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      6886867e
  45. 01 7月, 2014 1 次提交