RE: [Xen-devel] [Patch] Disallow SMEP for PV guest

To:	Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, "Yang, Wei Y" <wei.y.yang@xxxxxxxxx>
Subject:	RE: [Xen-devel] [Patch] Disallow SMEP for PV guest
From:	"Li, Xin" <xin.li@xxxxxxxxx>
Date:	Wed, 1 Jun 2011 23:17:58 +0800
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Thread-topic:	[Xen-devel] [Patch] Disallow SMEP for PV guest

> On Wed, Jun 01, 2011 at 10:31:12PM +0800, Yang, Wei Y wrote:
> > This patch disallows SMEP for PV guest.
> 
> What are the reasons for it? What do we gain from it?

X86_64 pv guests runs in ring3, which SMEP doesn't apply to.

Kernel supports SMEP will set it thru writing to CR4, probably we can silently 
ignore such writes from PV guests, but better to not let guest see it.

Thanks!
-Xin

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RE: [Xen-devel] [Patch] Disallow SMEP for PV guest