linux-kernel - [PATCH 08/10] KVM: SVM: Mark VMCB dirty before processing incoming snp_vmsa

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Message-ID: <20250219012705.1495231-9-seanjc@google.com>
Date: Tue, 18 Feb 2025 17:27:03 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Naveen N Rao <naveen@...nel.org>, Kim Phillips <kim.phillips@....com>, 
	Tom Lendacky <thomas.lendacky@....com>, Alexey Kardashevskiy <aik@....com>
Subject: [PATCH 08/10] KVM: SVM: Mark VMCB dirty before processing incoming snp_vmsa_gpa

Mark the VMCB dirty, i.e. zero control.clean, prior to handling the new
VMSA.  Nothing in the VALID_PAGE() case touches control.clean, and
isolating the VALID_PAGE() code will allow simplifying the overall logic.

Note, the VMCB probably doesn't need to be marked dirty when the VMSA is
invalid, as KVM will disallow running the vCPU in such a state.  But it
also doesn't hurt anything.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/sev.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 241cf7769508..3a531232c3a1 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3852,6 +3852,12 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
 	/* Clear use of the VMSA */
 	svm->vmcb->control.vmsa_pa = INVALID_PAGE;
 
+	/*
+	 * When replacing the VMSA during SEV-SNP AP creation,
+	 * mark the VMCB dirty so that full state is always reloaded.
+	 */
+	vmcb_mark_all_dirty(svm->vmcb);
+
 	if (VALID_PAGE(svm->sev_es.snp_vmsa_gpa)) {
 		gfn_t gfn = gpa_to_gfn(svm->sev_es.snp_vmsa_gpa);
 		struct kvm_memory_slot *slot;
@@ -3897,12 +3903,6 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
 		kvm_release_page_clean(page);
 	}
 
-	/*
-	 * When replacing the VMSA during SEV-SNP AP creation,
-	 * mark the VMCB dirty so that full state is always reloaded.
-	 */
-	vmcb_mark_all_dirty(svm->vmcb);
-
 	return 0;
 }
 
-- 
2.48.1.601.g30ceb7b040-goog