From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH] VMX: disable SMEP feature when guest is in
 non-paging mode
Date: Wed, 30 Jan 2013 17:11:51 -0800
Message-ID: <CD2F04D7.4B2B3%keir.xen@gmail.com>
References: <40776A41FC278F40B59438AD47D147A90FF0A622@SHSMSX102.ccr.corp.intel.com>
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To: "Xu, Dongxiao" <dongxiao.xu@intel.com>, Tim Deegan <tim@xen.org>
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On 30/01/2013 16:56, "Xu, Dongxiao" <dongxiao.xu@intel.com> wrote:

>>> Shouldn't this be handled on CR0 writes as well as CR4?  The SMEP bit of
>>> hw_cr[4] ought to be cleared and set whenever CR0_PG is changed.
>> 
>> That's what I would expect too.
> 
> In the case 0 (CR0 update) in vmx_update_guest_cr(), it will call
> vmx_update_guest_cr(v, 4) to adjust CR4 related bits if certain bits (PG, PE)
> in CR0 changed.

Good point!

In fact we can make that cr4 update unconditional and simplify the cr0
handling a bit more.

 -- Keir