From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <JBeulich@novell.com>
Subject: Re: [PATCH] xen svm: fix PAUSE instruction
	 intercept
Date: Thu, 12 Aug 2010 11:07:54 +0100
Message-ID: <4C63E41A020000780000F773@vpn.id2.novell.com>
References: <201008121122.36706.Christoph.Egger@amd.com>
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To: Christoph Egger <Christoph.Egger@amd.com>
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>>> On 12.08.10 at 11:22, Christoph Egger <Christoph.Egger@amd.com> wrote:
> In svm_vmexit_do_pause() update the instruction pointer.
> This fixes strange PAUSE intercepts on UP guests.

This won't work when the instruction needs to actually be decoded:
__get_instruction_length_from_list() strips all prefix bytes from
the byte stream being decoded, and since 'pause' uses a prefix the
actual opcode comparison will never produce a match.

Even in the case that CPUs supporting the pause filter would always
support nextrip I think that the special case minimally deserves a
code comment to that effect, but perhaps even warrants an
ASSERT() or BUG_ON().

Jan