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Re: [Xen-devel] [for-4.7] x86/emulate: synchronize LOCKed instruction emulation

To: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxx>
From: David Vrabel <david.vrabel@xxxxxxxxxx>
Date: Thu, 14 Apr 2016 11:35:11 +0100
Cc: keir@xxxxxxx, george.dunlap@xxxxxxxxxxxxx, andrew.cooper3@xxxxxxxxxx, ian.jackson@xxxxxxxxxxxxx, tim@xxxxxxx, paul.durrant@xxxxxxxxxx, jbeulich@xxxxxxxx, wei.liu2@xxxxxxxxxx
Delivery-date: Thu, 14 Apr 2016 10:35:35 +0000
List-id: Xen developer discussion <xen-devel.lists.xen.org>

On 13/04/16 13:26, Razvan Cojocaru wrote:
> LOCK-prefixed instructions are currenly allowed to run in parallel
> in x86_emulate(), which can lead the guest into an undefined state.
> This patch fixes the issue.

Is this sufficient?  What if another VCPU is running on another PCPU and
doing an unemulated LOCK-prefixed instruction to the same memory address?

This other VCPU could be for another domain (or Xen for that matter).

David

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  - From: Razvan Cojocaru

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