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





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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