Re: [PATCH v3 08/21] KVM:x86: Init kvm_caps.supported_xss with supported feature bits

Yang, Weijiang
2023-06-08T05:44:40Z

On 6/6/2023 4:38 PM, Chao Gao wrote:
> On Thu, May 11, 2023 at 12:08:44AM -0400, Yang Weijiang wrote:
>> Initialize kvm_caps.supported_xss with host XSS msr value AND XSS mask.
>> KVM_SUPPORTED_XSS holds all potential supported feature bits,
>> the result
>> represents all KVM supported feature bits which is used for swapping guest
>> and host FPU contents.
> do you mean kvm_caps.supported_xss by "the result"? I don't see how
> fpu_swap_kvm_fpstate() uses kvm_caps.supported_xss.

The wording is not accurate, what I meant is : the resulting bits are
supported by

fpu_swap_kvm_fpstate(). I will change the commit logs in next version, thanks!

>
>> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>> ---
>> arch/x86/kvm/vmx/vmx.c | 1 -
>> arch/x86/kvm/x86.c | 6 +++++-
>> 2 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index 44fb619803b8..c872a5aafa50 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -7806,7 +7806,6 @@ static __init void vmx_set_cpu_caps(void)
>> kvm_cpu_cap_set(X86_FEATURE_UMIP);
>>
>> /* CPUID 0xD.1 */
>> - kvm_caps.supported_xss = 0;
> AMD has the same statement. Do you need to remove that one?

Since it appears in svm.c, so I assume Allen(AMD) will change it

in his following up patch series. …