From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH RFC 8/9] xen: Generic instruction
 re-execution mechanism for execute faults
Date: Wed, 2 Jul 2014 17:04:12 +0100
Message-ID: <53B42D7C.1000004@citrix.com>
References: <1404308041-15461-1-git-send-email-rcojocaru@bitdefender.com>
	<1404308041-15461-8-git-send-email-rcojocaru@bitdefender.com>
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To: Razvan Cojocaru <rcojocaru@bitdefender.com>, xen-devel@lists.xen.org
Cc: Andrei Lutas <vlutas@bitdefender.com>, tim@xen.org
List-Id: xen-devel@lists.xenproject.org

On 02/07/14 14:34, Razvan Cojocaru wrote:
> The Xen emulator is incapable of handling some instructions, which
> leads to the injection of an Invalid Opcode exception (#UD) inside
> the guest once an unsupported instruction is encountered.

This is (as far as I am aware) simply because Xen's current emulation
only expects to emulate instructions which trapped for MMIO or fault
reasons.

There is no conceptual problem with extending Xen's emulation code, as
we are now expecting to have to emulate instructions which would
otherwise never have hit x86_emulate.

~Andrew