linux-kernel - [PATCH v2] KVM: nVMX: Mark APIC access page dirty when syncing vmcs12 pages

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Message-ID: <20250910085156.1419090-1-griffoul@gmail.com>
Date: Wed, 10 Sep 2025 08:51:55 +0000
From: Fred Griffoul <griffoul@...il.com>
To: kvm@...r.kernel.org
Cc: Fred Griffoul <fgriffo@...zon.co.uk>,
	Sean Christopherson <seanjc@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] KVM: nVMX: Mark APIC access page dirty when syncing vmcs12 pages

From: Fred Griffoul <fgriffo@...zon.co.uk>

For consistency with commit 7afe79f5734a ("KVM: nVMX: Mark vmcs12's APIC
access page dirty when unmapping"), which marks the page dirty during
unmap operations, also mark it dirty during vmcs12 page synchronization.

Signed-off-by: Fred Griffoul <fgriffo@...zon.co.uk>
---
v2: Fix commit ID to use 12 chars instead of 11 (checkpatch warning)

 arch/x86/kvm/vmx/nested.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b8ea1969113d..02aee6dd1698 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3916,10 +3916,10 @@ void nested_mark_vmcs12_pages_dirty(struct kvm_vcpu *vcpu)
 	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
 	gfn_t gfn;

-	/*
-	 * Don't need to mark the APIC access page dirty; it is never
-	 * written to by the CPU during APIC virtualization.
-	 */
+	if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
+		gfn = vmcs12->apic_access_addr >> PAGE_SHIFT;
+		kvm_vcpu_mark_page_dirty(vcpu, gfn);
+	}

 	if (nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) {
 		gfn = vmcs12->virtual_apic_page_addr >> PAGE_SHIFT;
--
2.43.0