Re: [PATCH 0/5] Split the emulator: decode & execute

[Laurent Vivier <Laurent.Vivier-6ktuUTfB/bM@public.gmane.org>]

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Avi Kivity wrote:
> Laurent Vivier wrote:
>> These patches split the emulator in two parts: one to decode the
>> instruction,
>> the other to execute it. The decode part is then called only when needed.
>>
>>   
> 
> Patchset looks good, but fails booting FC6 x86-64 on Intel.  It may be a
> merge error (did not apply cleanly due to other changes).  I pushed this
> as a 'split-emulator' branch on the kvm.git repository.
> 

I think I found the bug (not a merge error...): I just supposed that an
instruction fetch cannot failed.

I wrote:

      r = x86_decode_insn(&emulate_ctxt, &emulate_ops);
      if (r)
              return EMULATE_FAIL;

     vcpu->mmio_is_write = 0;
     vcpu->pio.string = 0;
     r = x86_emulate_insn(&emulate_ctxt, &emulate_ops);
     ...

It should be:

      vcpu->mmio_is_write = 0;
      vcpu->pio.string = 0;

      r = x86_decode_insn(&emulate_ctxt, &emulate_ops);
      if (r == 0) {
              r = x86_emulate_insn(&emulate_ctxt, &emulate_ops);
              if (vcpu->pio.string)
                      return EMULATE_DO_MMIO;
      }

      if ((r || vcpu->mmio_is_write) && run) {
      ...
      }

      if (r) {
      ...
      }

Laurent
-- 
------------- Laurent.Vivier-6ktuUTfB/bM@public.gmane.org  --------------
          "Software is hard" - Donald Knuth


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