Re: [Qemu-devel] Status of my hacks on the MTTCG WIP branch

[Alex Bennée]

KONRAD Frederic <address@hidden> writes:

> Le 14/01/2016 14:10, Alex Bennée a écrit :
>> Alex Bennée <address@hidden> writes:
>>
>>> Pranith Kumar <address@hidden> writes:
>>>
>>>> Hi Alex,
>>>>
>>>> On Tue, Jan 12, 2016 at 12:29 PM, Alex Bennée <address@hidden>
>>>> wrote:
>>>>
>>>> https://github.com/stsquad/qemu/tree/mttcg/multi_tcg_v8_wip_ajb_fix_locks
>>>> I built this branch and ran an arm64 guest. It seems to be failing
>>>> similarly to what I reported earlier:
>>>>
>>>> #0  0x00007ffff2211cc9 in __GI_raise (address@hidden) at
>>>> ../nptl/sysdeps/unix/sysv/linux/raise.c:56
>>>> #1  0x00007ffff22150d8 in __GI_abort () at abort.c:89
>>>> #2  0x000055555572014c in qemu_ram_addr_from_host_nofail
>>>> (ptr=0xffffffc000187863) at /home/pranith/devops/code/qemu/cputlb.c:357
>>>> #3  0x00005555557209dd in get_page_addr_code (env1=0x555556702058,
>>>> addr=18446743798833248356) at /home/pranith/devops/code/qemu/cputlb.c:568
>>>> #4  0x00005555556db98c in tb_find_physical (cpu=0x5555566f9dd0,
>>>> pc=18446743798833248356, cs_base=0, flags=18446744071830503424) at
>>>> /home/pranith/devops/code/qemu/cpu-exec.c:224
>>>> #5  0x00005555556dbaf4 in tb_find_slow (cpu=0x5555566f9dd0,
>>>> pc=18446743798833248356, cs_base=0, flags=18446744071830503424) at
>>>> /home/pranith/devops/code/qemu/cpu-exec.c:268
>>>> #6  0x00005555556dbc77 in tb_find_fast (cpu=0x5555566f9dd0) at
>>>> /home/pranith/devops/code/qemu/cpu-exec.c:311
>>>> #7  0x00005555556dc0f1 in cpu_arm_exec (cpu=0x5555566f9dd0) at
>>>> /home/pranith/devops/code/qemu/cpu-exec.c:492
>>>> #8  0x00005555557050ee in tcg_cpu_exec (cpu=0x5555566f9dd0) at
>>>> /home/pranith/devops/code/qemu/cpus.c:1486
>>>> #9  0x00005555557051af in tcg_exec_all (cpu=0x5555566f9dd0) at
>>>> /home/pranith/devops/code/qemu/cpus.c:1515
>>>> #10 0x0000555555704800 in qemu_tcg_cpu_thread_fn (arg=0x5555566f9dd0) at
>>>> /home/pranith/devops/code/qemu/cpus.c:1187
>>>> #11 0x00007ffff25a8182 in start_thread (arg=0x7fffd20c8700) at
>>>> pthread_create.c:312
>>>> #12 0x00007ffff22d547d in clone () at
>>>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
>> <snip>
>>
>> Having seen a backtrace of a crash while the other thread was flushing
>> the TLB entries I sprinkled a bunch of:
>>
>>    g_assert(cpu == current_cpu);
>>
>> In all public functions in cputlb that took a CPU. There are a bunch of
>> cases that don't defer actions across CPUs which need to be fixed up. I
>> suspect they don't hit in the arm case because the type of TLB flushing
>> pattern is different. In aarch64 it my backtrace it was triggered by
>> tlbi_aa64_vae1is_write:
>>
>>    7    Thread 0x7ffe777fe700 (LWP 32705) "worker" sem_timedwait () at 
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_timedwait.S:101
>>    6    Thread 0x7ffe77fff700 (LWP 32704) "worker" sem_timedwait () at 
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_timedwait.S:101
>>    5    Thread 0x7fff8d9d0700 (LWP 32703) "CPU 1/TCG" 0x000055555572cc18 in 
>> memcpy (__len=8, __src=<synthetic pointer>, __dest=<optimised out>)
>>      at /usr/include/x86_64-linux-gnu/bits/string3.h:51
>> * 4    Thread 0x7fff8e1d1700 (LWP 32702) "CPU 0/TCG" memset () at 
>> ../sysdeps/x86_64/memset.S:94
>>    3    Thread 0x7fff8f1cb700 (LWP 32701) "worker" sem_timedwait () at 
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_timedwait.S:101
>>    2    Thread 0x7fffe45c8700 (LWP 32700) "qemu-system-aar" syscall () at 
>> ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38
>>    1    Thread 0x7ffff7f98c00 (LWP 32696) "qemu-system-aar" 
>> 0x00007ffff0ba01ef in __GI_ppoll (fds=0x5555575cb5b0, nfds=8, 
>> timeout=<optimised out>,
>>      address@hidden, address@hidden) at ../sysdeps/unix/sysv/linux/ppoll.c:56
>> #0  memset () at ../sysdeps/x86_64/memset.S:94
>> #1  0x0000555555728bee in memset (__len=32768, __ch=0, 
>> __dest=0x555556632568) at /usr/include/x86_64-linux-gnu/bits/string3.h:84
>> #2  v_tlb_flush_by_mmuidx (argp=0x7fff8e1d0430, cpu=0x555556632380) at 
>> /home/alex/lsrc/qemu/qemu.git/cputlb.c:136
>> #3  tlb_flush_page_by_mmuidx (address@hidden, address@hidden) at 
>> /home/alex/lsrc/qemu/qemu.git/cputlb.c:243
>> #4  0x00005555557fcb4a in tlbi_aa64_vae1is_write (env=<optimised out>, 
>> ri=<optimised out>, value=<optimised out>)
>>      at /home/alex/lsrc/qemu/qemu.git/target-arm/helper.c:2757
>> #5  0x00007fffa441dac5 in code_gen_buffer ()
>> #6  0x00005555556eef4b in cpu_tb_exec (tb_ptr=<optimised out>, 
>> cpu=0x5555565eddd0) at /home/alex/lsrc/qemu/qemu.git/cpu-exec.c:157
>> #7  cpu_arm_exec (address@hidden) at 
>> /home/alex/lsrc/qemu/qemu.git/cpu-exec.c:520
>> #8  0x00005555557108e8 in tcg_cpu_exec (cpu=0x5555565eddd0) at 
>> /home/alex/lsrc/qemu/qemu.git/cpus.c:1486
>> #9  tcg_exec_all (cpu=0x5555565eddd0) at 
>> /home/alex/lsrc/qemu/qemu.git/cpus.c:1515
>> #10 qemu_tcg_cpu_thread_fn (arg=0x5555565eddd0) at 
>> /home/alex/lsrc/qemu/qemu.git/cpus.c:1187
>> #11 0x00007ffff0e80182 in start_thread (arg=0x7fff8e1d1700) at 
>> pthread_create.c:312
>> #12 0x00007ffff0bad47d in clone () at 
>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
>> [Switching to thread 5 (Thread 0x7fff8d9d0700 (LWP 32703))]
>> #0  0x000055555572cc18 in memcpy (__len=8, __src=<synthetic pointer>, 
>> __dest=<optimised out>) at /usr/include/x86_64-linux-gnu/bits/string3.h:51
>> 51     return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest));
>> #0  0x000055555572cc18 in memcpy (__len=8, __src=<synthetic pointer>, 
>> __dest=<optimised out>) at /usr/include/x86_64-linux-gnu/bits/string3.h:51
>> #1  stq_he_p (v=<optimised out>, ptr=<optimised out>) at 
>> /home/alex/lsrc/qemu/qemu.git/include/qemu/bswap.h:292
>> #2  stq_le_p (v=547973099520, ptr=<optimised out>) at 
>> /home/alex/lsrc/qemu/qemu.git/include/qemu/bswap.h:327
>> #3  helper_le_stq_mmu (env=0x55555663a608, addr=18446743801961580216, 
>> val=547973099520, oi=<optimised out>, retaddr=140735948385557)
>>      at /home/alex/lsrc/qemu/qemu.git/softmmu_template.h:455
>> #4  0x00007fffa435ed17 in code_gen_buffer ()
>> #5  0x00005555556eef4b in cpu_tb_exec (tb_ptr=<optimised out>, 
>> cpu=0x555556632380) at /home/alex/lsrc/qemu/qemu.git/cpu-exec.c:157
>> #6  cpu_arm_exec (address@hidden) at 
>> /home/alex/lsrc/qemu/qemu.git/cpu-exec.c:520
>> #7  0x00005555557108e8 in tcg_cpu_exec (cpu=0x555556632380) at 
>> /home/alex/lsrc/qemu/qemu.git/cpus.c:1486
>> #8  tcg_exec_all (cpu=0x555556632380) at 
>> /home/alex/lsrc/qemu/qemu.git/cpus.c:1515
>> #9  qemu_tcg_cpu_thread_fn (arg=0x555556632380) at 
>> /home/alex/lsrc/qemu/qemu.git/cpus.c:1187
>> #10 0x00007ffff0e80182 in start_thread (arg=0x7fff8d9d0700) at 
>> pthread_create.c:312
>> #11 0x00007ffff0bad47d in clone () at 
>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
>> A debugging session is active.
>>
>> Needless to say anything messing with structures used by the other
>> threads needs to take great care or doom will occur ;-)
>>
>> I'll look at fixing them up in my tree while Fred finishes his re-base.
>>
>> --
>> Alex Bennée
> Hi,
>
> Is that possible those one have been added since the V7 version?
> I saw some changes there.

My tree is based of your -wip branch (I called it -v8-wip). How is the
official re-base going?

>
> Thanks,
> Fred


--
Alex Bennée