From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH] KVM: x86 emulator: reject SYSENTER in compatibility mode
 on AMD guests
Date: Wed, 1 Feb 2012 09:00:44 -0200
Message-ID: <20120201110044.GA26183@amt.cnet>
References: <1328092020-18511-1-git-send-email-avi@redhat.com>
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	Stephan =?iso-8859-1?Q?B=E4rwolf?=
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To: Avi Kivity <avi@redhat.com>
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On Wed, Feb 01, 2012 at 12:27:00PM +0200, Avi Kivity wrote:
> If the guest thinks it's an AMD, it will not have prepared the SYSENTER MSRs,
> and if the guest executes SYSENTER in compatibility mode, it will fails.
> 
> Detect this condition and #UD instead, like the spec says.

Note the SYSENTER_CS & 0xfffc == 0 check protects against a fatal error (unlike
the SYSCALL bug), in case of zeroed MSRs.