Re: [Xen-devel] [PATCH] Fix races in iret hypercall - Keir Fraser - com.xensource.lists.xen-devel

2 messages in com.xensource.lists.xen-develRe: [Xen-devel] [PATCH] Fix races in ...

From	Sent On	Attachments
Christoph Egger	09 Aug 2007 01:34	.diff
Keir Fraser	09 Aug 2007 01:44

Subject:	Re: [Xen-devel] [PATCH] Fix races in iret hypercall
From:	Keir Fraser (ke...@xensource.com)
Date:	08/09/2007 01:44:18 AM
List:	com.xensource.lists.xen-devel

On 9/8/07 09:35, "Christoph Egger" <Chri...@amd.com> wrote:

Attached patch fixes races seen on SMP when multiple HVM guests execute the iret instruction at the same time.

current vcpu can change in the middle of do_iret().

This is fine as a cleanup, but it does not fix any bugs!

For two reasons: 1. Current vcpu *cannot* change in the middle of do_iret(). Xen does not support involuntary preemption. 2. HVM guests do not ever execute do_iret(). That function is for pv guests only.

How did you conclude there was a bug?

-- Keir