[PATCH 7.2.y 2/8] KVM: SEV: Extract loading of guest-provided VMSA to a separate helper

[Sasha Levin <sashal@kernel.org>]

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit 0060569e4f18a7dee2dd8728595e909f19a23c24 ]

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@vger.kernel.org # 6.12.x
Reviewed-by: Michael Roth <michael.roth@amd.com>
Link: https://patch.msgid.link/20260709204948.1988414-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Stable-dep-of: d1a3c2162334 ("KVM: SEV: Forcefully invalidate SNP VMSA if its backing gmem page is zapped")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 5924d739c7adb..25e5948ccc19f 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3998,29 +3998,17 @@ 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);
-
-	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);
+	lockdep_assert_held(&svm->sev_es.snp_vmsa_mutex);
 
-	/* 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;
 
@@ -4030,12 +4018,9 @@ 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;
@@ -4059,7 +4044,7 @@ 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 */
@@ -4073,6 +4058,31 @@ 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);
-- 
2.53.0