Xen devel - Jun 2007 - RE: [Xen-changelog] [xen-unstable] hvm: Sync SVM CR4 handling with VMX.

> diff -r 5eec9a8825d4 -r 87d34c8c2fe1 xen/include/asm-x86/hvm/hvm.h
> --- a/xen/include/asm-x86/hvm/hvm.h	Wed Jun 27 20:08:21 2007 +0100
> +++ b/xen/include/asm-x86/hvm/hvm.h	Wed Jun 27 20:17:54 2007 +0100
> @@ -302,10 +302,17 @@ static inline int hvm_event_injection_fa
>      return hvm_funcs.event_injection_faulted(v);
>  }
>  
> -/* 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. 

--
Mats



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On 28/6/07 11:33, "Petersson, Mats" <Mats.Petersson@amd.com>
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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