Re: [PATCH 0/4] target/ppc: Catch invalid real address accesses

["Cédric Le Goater" <clegoate@redhat.com>]

On 6/29/23 10:29, Mark Cave-Ayland wrote:
> On 28/06/2023 08:17, Cédric Le Goater wrote:
> 
>>>>>> qemu-system-ppc.exe -M mac99,via=pmu -cdrom C:\mac-iso\9.2.2.iso -boot d -L pc-bios
>>>>>> crashes Mac OS with an address error. (with unpatched and patched builds).
>>>>>
>>>>> Same on Linux. I get an invalid opcode. QEMU 7.2 work fine though.
>>>>>
>>>>> C.
>>>>
>>>> That certainly shouldn't happen, and if it worked in 7.2 then there's definitely a regression which has crept in there somewhere. I'll try and bisect this at some point soon, but feel free to try and beat me ;)
>>>
>>> bisect points to :
>>>
>>> commit e506ad6a05c806bbef460a7d014a184ff8d707a6
>>> Author: Richard Henderson <richard.henderson@linaro.org>
>>> Date:   Mon Mar 6 04:30:11 2023 +0300
>>>
>>>      accel/tcg: Pass last not end to tb_invalidate_phys_range
>>>      Pass the address of the last byte to be changed, rather than
>>>      the first address past the last byte.  This avoids overflow
>>>      when the last page of the address space is involved.
>>>      Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>>>      Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>>>
>>>   include/exec/exec-all.h   |  2 +-
>>>   accel/tcg/tb-maint.c      | 31 ++++++++++++++++---------------
>>>   accel/tcg/translate-all.c |  2 +-
>>>   accel/tcg/user-exec.c     |  2 +-
>>>   softmmu/physmem.c         |  2 +-
>>>   5 files changed, 20 insertions(+), 19 deletions(-)
>>>
>>>
>>> I think the instruction is fnmadds. Needs more digging.
>>
>> the invalid opcode is just a symptom of something bad happening.
>>
>> C.
> 
> Indeed, it appears to be a copy/paste error within that commit. I've just posted a proposed fix for this: https://lore.kernel.org/qemu-devel/20230629082522.606219-1-mark.cave-ayland@ilande.co.uk/T/.

Looks good. I could boot macos 9.2.1 from an iso and 9.2.2 from disk.

> Nick: you may wish to try your series again with this fix applied to see if there are still problems with the CPUs used in the Mac machines.

Looks good too, with these :

  [PATCH v2 1/4] target/ppc: Machine check on invalid real address
  [PATCH v2 2/4] target/ppc: Move common check in machine check
  [PATCH v2 3/4] target/ppc: Make checkstop actually stop the system


Patch 4 (attn) doesn't compile but it's an extra behavior on top of
checkstop.

Thanks,

C.