On Tue, Mar 16, 2010 at 11:37:35AM +0200, Avi Kivity wrote:
> On 03/15/2010 08:10 PM, Gleb Natapov wrote:
> >On Mon, Mar 15, 2010 at 04:46:20PM +0100, Andre Przywara wrote:
> >>Gleb Natapov wrote:
> >>>If LOCK prefix is used dest arg should be memory, otherwise instruction
> >>>should generate #UD.
> >>Well, there is one exception:
> >>There is an AMD specific "lock mov cr0 = mov cr8" equivalence, where
> >>there is no memory involved (and we intercept this). I am not sure
> >>if anyone actually uses this code sequence, but it is definitely
> >>legal.
> >>
> >Even without this patch "lock mov cr0" will cause #UD to be injected by
> >emulator since mov does not have Lock in opcode table. Also it look like
> >Intel does not support this extension so no portable program can use
> >it.
> >
>
> A portable program can check for this instruction in cpuid and only
> issue it if it is supported.
>
Yes, indeed there is cpuid for that. It looks like our decoder needs one
more layer of transformation to distinguish between regular prefixes and
prefixes that modifies opcode meaning.
--
Gleb.
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