Re: [PATCH v3 1/5] KVM: SVM: Refactor svm_update_lbrv()

[Shivansh Dhiman <shivansh.dhiman@amd.com>]

On 10-07-26 01:23, Yosry Ahmed wrote:
> On Thu, Jul 9, 2026 at 1:31 AM Shivansh Dhiman <shivansh.dhiman@amd.com> wrote:
>>
>> Rewrite the enable_lbrv computation in svm_update_lbrv() as a series of
>> 'if' statements, and use nested_vmcb12_has_lbrv() instead of open-coding
>> the nested LBRV check.
>>
>> No functional change intended.
>>
>> Suggested-by: Yosry Ahmed <yosry@kernel.org>
>> Signed-off-by: Shivansh Dhiman <shivansh.dhiman@amd.com>
>> ---
>> Changelog:
>> v3:
>>  * New patch.
>>  * Refactor the enable_lbrv computation into 'if' statements (Yosry Ahmed).
>>
>> ---
>>  arch/x86/kvm/svm/nested.c |  2 +-
>>  arch/x86/kvm/svm/svm.c    | 10 +++++++---
>>  arch/x86/kvm/svm/svm.h    |  1 +
>>  3 files changed, 9 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
>> index c1485c3e691c..d3df6b22bfef 100644
>> --- a/arch/x86/kvm/svm/nested.c
>> +++ b/arch/x86/kvm/svm/nested.c
>> @@ -736,7 +736,7 @@ static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
>>         return 0;
>>  }
>>
>> -static bool nested_vmcb12_has_lbrv(struct kvm_vcpu *vcpu)
>> +bool nested_vmcb12_has_lbrv(struct kvm_vcpu *vcpu)
> 
> We might wanna rename this function now that we are exposing it
> outside of nested.c, but otherwise this looks good to me:

Agreed, will rename it to nested_lbrv_enabled() in v4.

> 
> Reviewed-by: Yosry Ahmed <yosry@kernel.org>

Thanks for the review!

> 
>>  {
>>         return guest_cpu_cap_has(vcpu, X86_FEATURE_LBRV) &&
>>                 (to_svm(vcpu)->nested.ctl.misc_ctl2 & SVM_MISC2_ENABLE_V_LBR);