[PATCH 6.12.y 3/6] KVM: SVM: Invalidate "next" SNP VMSA GPA even on failure

[Sasha Levin <sashal@kernel.org>]

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit 4e96f010afb2815e33c9b15a695e0e0b4cb3cea6 ]

When processing an SNP AP Creation event, invalidate the "next" VMSA GPA
even if acquiring the page/pfn for the new VMSA fails.  In practice, the
next GPA will never be used regardless of whether or not its invalidated,
as the entire flow is guarded by snp_ap_waiting_for_reset, and said guard
and snp_vmsa_gpa are always written as a pair.  But that's really hard to
see in the code.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20250227012541.3234589-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Stable-dep-of: 42a39ad5d592 ("KVM: SEV: Track the GPA of the guest-controlled VMSA used for SNP guests")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/svm/sev.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index be6150ec1b2f2..7a94a5f0ca805 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3945,6 +3945,7 @@ void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
 		return;
 
 	gfn = gpa_to_gfn(svm->sev_es.snp_vmsa_gpa);
+	svm->sev_es.snp_vmsa_gpa = INVALID_PAGE;
 
 	slot = gfn_to_memslot(vcpu->kvm, gfn);
 	if (!slot)
@@ -3975,8 +3976,6 @@ void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
 	vcpu->arch.pv.pv_unhalted = false;
 	vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
 
-	svm->sev_es.snp_vmsa_gpa = INVALID_PAGE;
-
 	/*
 	 * gmem pages aren't currently migratable, but if this ever changes
 	 * then care should be taken to ensure svm->sev_es.vmsa is pinned
-- 
2.53.0