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Re: [Xen-devel] RE: [Xen-changelog] [xen-unstable] hvm: Sync SVM CR4 han

To: "Petersson, Mats" <Mats.Petersson@xxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>, <xen-changelog@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] RE: [Xen-changelog] [xen-unstable] hvm: Sync SVM CR4 handling with VMX.
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Thu, 28 Jun 2007 13:57:28 +0100
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Thread-topic: [Xen-devel] RE: [Xen-changelog] [xen-unstable] hvm: Sync SVM CR4 handling with VMX.
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On 28/6/07 11:33, "Petersson, Mats" <Mats.Petersson@xxxxxxx> wrote:

>> -/* These bits in the CR4 are owned by the host */
>> +/* These bits in CR4 are owned by the host. */
>>  #define HVM_CR4_HOST_MASK (mmu_cr4_features & \
>>      (X86_CR4_VMXE | X86_CR4_PAE | X86_CR4_MCE))
> VMXE is only for Intel, so being very picky, it shouldn't be in a HVM
> environment. 
> I don't think it's a problem as, I doubt very much that AMD would use
> this bit for anything in the future, as Intel has "occupied it", and
> we're using a different way to enable SVM.

The code is entirely benign on AMD until that happens *and* we actually make
use of it by adding it to mmu_cr4_features. So this is the way of simplest
code for now.

 -- Keir

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