Re: [Xen-devel] [PATCH 4/6] libxc: expose xsaves/xgetbv1/xsavec to hvm guest

["Ruan, Shuai" <shuai.ruan@xxxxxxxxx>]

Thanks for your reviews Jan.
Can you give me some suggestion on this?  In PATCH03, I change hvm_cpuid 
function to make sure the CPUID data can be exposed to guest when xsaves 
supported.  

-----Original Message-----
From: Jan Beulich [mailto:JBeulich@xxxxxxxx] 
Sent: Friday, July 17, 2015 6:47 PM
To: Ruan, Shuai
Cc: andrew.cooper3@xxxxxxxxxx; Ian.Campbell@xxxxxxxxxx; wei.liu2@xxxxxxxxxx; 
ian.jackson@xxxxxxxxxxxxx; stefano.stabellini@xxxxxxxxxxxxx; Dong, Eddie; 
Nakajima, Jun; Tian, Kevin; xen-devel@xxxxxxxxxxxxx; keir@xxxxxxx
Subject: RE: [PATCH 4/6] libxc: expose xsaves/xgetbv1/xsavec to hvm guest

>>> On 17.07.15 at 10:10, <shuai.ruan@xxxxxxxxx> wrote:
> Ok, Thanks Jan.
> I will add the descriptions in next version.
> 
> Below is the short descriptions.
> For CPUID with eax=0xd and ecx=0x1, ebx\ecx\edx may not be zero when 
> xsaves supported. Also with ecx>2, ecx\edx may not be zero. If we want 
> expose xsaves to HVM guest , we should not set them to zero.
> 
> So in your opinions ,is it proper to add these code here?

Sure, provided you don't leak any bits that may become defined in the future, 
and the non-zero setting of which might be inconsistent with other CPUID data. 
I.e. without looking at the manual, I'd guess the above is still a little too 
vague.

Jan


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