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RE: [Xen-devel] [PATCH][VT] No DISALLOW pte bit check for VMX domain

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH][VT] No DISALLOW pte bit check for VMX domain
From: "Li, Chengyuan" <chengyuan.li@xxxxxxxxx>
Date: Mon, 12 Sep 2005 21:55:25 +0800
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] [PATCH][VT] No DISALLOW pte bit check for VMX domain
Keir Fraser scribbled on 2005年9月12日 18:06:

> On 12 Sep 2005, at 08:05, Li, Chengyuan wrote:
> 
>> Hi,
>> 
>> VMX domain don't need DISALLOW pte bit checking.
>> 
>> Signed-off-by: Chengyuan Li <chengyuan.li@xxxxxxxxx>
> 
> I think they do need these checks. get_page_from_l1e() is only called
> on real pagetables, even in shadow mode (i.e., it is called for the
> shadow pte's). We still want to check that the guest isn't trying to
> set weird PAT values or, if it is, we need to deal with those
> explicitly. For now, I think the correct think to do is to apply
> L1_DISALLOW_MASK before calling get_page_from_l1e(). You already strip
> off the GLOBAL bit, but the rest should be stripped also.
Keir,

You are right. For VMX guest, we need care PAT bit, though we needn't care 
GLOBAL bit.

> 
>   -- Keir

Thanks,
Chengyuan

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