Re: [PATCH v3 02/12] KVM: SEV: Extract loading of guest-provided VMSA to a separate helper

[Michael Roth]

On Tue, Jun 30, 2026 at 03:25:57PM -0700, Sean Christopherson wrote:
> Extract the loading/retrieval of a guest-provided VMSA to a separate helper
> so that KVM can reuse the core logic when refreshing the VMSA after an MMU
> invalidation from guest_memfd.
> 
> No functional change intended.
> 
> Cc: stable@xxxxxxxxxxxxxxx # 6.12.x
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: Michael Roth <michael.roth@xxxxxxx>

> ---
>  arch/x86/kvm/svm/sev.c | 52 +++++++++++++++++++++++++-----------------
>  1 file changed, 31 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 827f5dc06102..d8ed00f76aa3 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -3979,29 +3979,17 @@ static int snp_begin_psc(struct vcpu_svm *svm)
>  	return snp_do_psc(svm);
>  }
>  
> -/*
> - * Invoked as part of svm_vcpu_reset() processing of an init event.
> - */
> -static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
> +static void sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa)
>  {
>  	struct vcpu_svm *svm = to_svm(vcpu);
>  	struct kvm_memory_slot *slot;
> +	gfn_t gfn = gpa_to_gfn(gpa);
>  	struct page *page;
>  	kvm_pfn_t pfn;
> -	gfn_t gfn;
>  
> -	guard(mutex)(&svm->sev_es.snp_vmsa_mutex);
> +	lockdep_assert_held(&svm->sev_es.snp_vmsa_mutex);
>  
> -	if (!svm->sev_es.snp_ap_waiting_for_reset)
> -		return;
> -
> -	svm->sev_es.snp_ap_waiting_for_reset = false;
> -
> -	/* Mark the vCPU as offline and not runnable */
> -	vcpu->arch.pv.pv_unhalted = false;
> -	kvm_set_mp_state(vcpu, KVM_MP_STATE_HALTED);
> -
> -	/* Clear use of the VMSA */
> +	/* Clear use of the VMSA. */
>  	svm->vmcb->control.vmsa_pa = INVALID_PAGE;
>  	svm->sev_es.snp_guest_vmsa_gpa = INVALID_PAGE;
>  
> @@ -4011,12 +3999,9 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
>  	 */
>  	vmcb_mark_all_dirty(svm->vmcb);
>  
> -	if (!VALID_PAGE(svm->sev_es.snp_pending_vmsa_gpa))
> +	if (!VALID_PAGE(gpa))
>  		return;
>  
> -	gfn = gpa_to_gfn(svm->sev_es.snp_pending_vmsa_gpa);
> -	svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
> -
>  	slot = gfn_to_memslot(vcpu->kvm, gfn);
>  	if (!slot)
>  		return;
> @@ -4040,7 +4025,7 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
>  	svm->sev_es.snp_has_guest_vmsa = true;
>  
>  	/* Use the new VMSA */
> -	svm->sev_es.snp_guest_vmsa_gpa = gfn_to_gpa(gfn);
> +	svm->sev_es.snp_guest_vmsa_gpa = gpa;
>  	svm->vmcb->control.vmsa_pa = pfn_to_hpa(pfn);
>  
>  	/* Mark the vCPU as runnable */
> @@ -4054,6 +4039,31 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
>  	kvm_release_page_clean(page);
>  }
>  
> +/*
> + * Invoked as part of svm_vcpu_reset() processing of an init event.
> + */
> +static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
> +{
> +	struct vcpu_svm *svm = to_svm(vcpu);
> +	gpa_t gpa;
> +
> +	guard(mutex)(&svm->sev_es.snp_vmsa_mutex);
> +
> +	if (!svm->sev_es.snp_ap_waiting_for_reset)
> +		return;
> +
> +	svm->sev_es.snp_ap_waiting_for_reset = false;
> +
> +	/* Mark the vCPU as offline and not runnable */
> +	vcpu->arch.pv.pv_unhalted = false;
> +	kvm_set_mp_state(vcpu, KVM_MP_STATE_HALTED);
> +
> +	gpa = svm->sev_es.snp_pending_vmsa_gpa;
> +	svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
> +
> +	sev_snp_reload_vmsa(vcpu, gpa);
> +}
> +
>  static int sev_snp_ap_creation(struct vcpu_svm *svm)
>  {
>  	struct kvm_sev_info *sev = to_kvm_sev_info(svm->vcpu.kvm);
> -- 
> 2.55.0.rc0.799.gd6f94ed593-goog
>