Re: [PATCH v3 07/21] KVM:x86: Refresh CPUID on write to guest MSR_IA32_XSS

Yang, Weijiang
2023-05-31T01:11:52Z

On 5/30/2023 8:08 PM, Chao Gao wrote:
>>>> --- a/arch/x86/kvm/x86.c
>>>> +++ b/arch/x86/kvm/x86.c
>>>> @@ -3776,8 +3776,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>>>> */
>>>> if (data & ~kvm_caps.supported_xss)
>>> Shouldn't we check against the supported value of _this_ guest? similar to
>>> guest_supported_xcr0.
>> I don't think it requires an extra variable to serve per guest purpose.
>>
>> For guest XSS settings, now we don't add extra constraints like XCR0, thus
> QEMU can impose constraints by configuring guest CPUID.0xd.1 to indicate
> certain supervisor state components cannot be managed by XSAVES, even
> though KVM supports them. IOW, guests may differ in the supported values
> for the IA32_XSS MSR.

OK, will change this part to align with xcr0 settings. Thanks!