Re: [Xen-devel] [PATCH v1] x86/hvm: Generic instruction re-execution mechanism for execute faults

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 5/14/19 5:16 PM, Jan Beulich wrote:
> > > > On 14.05.19 at 15:47, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> > Mem event emulation failed (5): d5v0 32bit @ 001b:6d96efff -> c5 f9 f5
> > 05 c0 be ad 6d c5 e1 fe 1d a0 20 af 6d
> >
> > Looking at the source code, the emulator does appear to support
> > vpmaddwd, however only for EVEX:
> >
> > http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/x86_emulate/x
> > 86_emulate.c;h=032995ea586aa7dd90a1953b6ded656436652049;hb=refs/heads/staging
> > #l6696
> >
> > whereas our fail case uses VEX.
> >
> > This may be in the works in the aforementioned series, but is
> > legitimately unsupported in 4.13 staging.
> Hmm, interesting. The origin of the encoding is at MMX times,
> which means it's more than just VPMADDWD that's missing, and
> it's been an omission back in the MMX/SSE2 series then. That's
> a genuine oversight, and in the light of this I'd like to apologize
> for my unfriendly initial reaction. I'll see about getting this fixed.
> (It would have helped if you had shared the encoding right away,
> since the mnemonic and operands are now often insufficient.)
No problem at all. Indeed, sharing the encoding would have cleared 
things up faster.

Thanks,
Razvan

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