linux-kernel - Re: [PATCH v2 2/2] KVM: SVM: Re-load current, not host, TSC

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Message-ID: <aNLHgel7cZZ1THrv@google.com>
Date: Tue, 23 Sep 2025 09:14:57 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Xiaoyao Li <xiaoyao.li@...el.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Hou Wenlong <houwenlong.hwl@...group.com>, Lai Jiangshan <jiangshan.ljs@...group.com>
Subject: Re: [PATCH v2 2/2] KVM: SVM: Re-load current, not host, TSC_AUX on
 #VMEXIT from SEV-ES guest

On Tue, Sep 23, 2025, Xiaoyao Li wrote:
> On 9/20/2025 5:38 AM, Sean Christopherson wrote:
> > ---
> >   arch/x86/kvm/svm/sev.c | 14 +++++++++++++-
> >   arch/x86/kvm/svm/svm.c | 26 +++++++-------------------
> >   arch/x86/kvm/svm/svm.h |  4 +++-
> >   3 files changed, 23 insertions(+), 21 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> > index cce48fff2e6c..95767b9d0d55 100644
> > --- a/arch/x86/kvm/svm/sev.c
> > +++ b/arch/x86/kvm/svm/sev.c
> > @@ -4664,7 +4664,9 @@ int sev_vcpu_create(struct kvm_vcpu *vcpu)
> >   	return 0;
> >   }
> > -void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_area *hostsa)
> > +void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm,
> > +				    struct sev_es_save_area *hostsa,
> > +				    int tsc_aux_uret_slot)
> 
> Passing the tsc_aux_uret_slot as paramter looks a bit ugly, how about
> externing it?

Yeah, looking at this again, I agree.  I'll post a v3 (already did; forgot to
hit "send" on this earlier, /facepalm).