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Re: [PATCH] x86emul: fix FXRSTOR test for most AMD CPUs

  • To: Jan Beulich <jbeulich@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Date: Mon, 6 Jul 2020 16:46:51 +0100
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  • Cc: Paul Durrant <paul@xxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Mon, 06 Jul 2020 15:47:31 +0000
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  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 06/07/2020 16:14, Jan Beulich wrote:
> AMD CPUs that we classify as X86_BUG_FPU_PTRS don't touch the selector/
> offset portion of the save image during FXSAVE unless an unmasked
> exception is pending. Hence the selector zapping done between the
> initial FXSAVE and the emulated FXRSTOR needs to be mirrored onto the
> second FXSAVE, output of which gets fed into memcmp() to compare with
> the input image.
> Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Tested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>



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