linux-kernel - [PATCH 2/2] KVM: SVM: Mark VMCB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20250922162935.621409-3-jmattson@google.com>
Date: Mon, 22 Sep 2025 09:29:23 -0700
From: Jim Mattson <jmattson@...gle.com>
To: 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>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Jim Mattson <jmattson@...gle.com>
Subject: [PATCH 2/2] KVM: SVM: Mark VMCB_NPT as dirty on nested VMRUN

Mark the VMCB_NPT bit as dirty in nested_vmcb02_prepare_save()
on every nested VMRUN.

If L1 changes the PAT MSR between two VMRUN instructions on the same
L1 vCPU, the g_pat field in the associated vmcb02 will change, and the
VMCB_NPT clean bit should be cleared.

Fixes: 4bb170a5430b ("KVM: nSVM: do not mark all VMCB02 fields dirty on nested vmexit")
Signed-off-by: Jim Mattson <jmattson@...gle.com>
---
 arch/x86/kvm/svm/nested.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 177a9764fb64..9ecdc462e98c 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -613,6 +613,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
 	struct kvm_vcpu *vcpu = &svm->vcpu;
 
 	nested_vmcb02_compute_g_pat(svm);
+	vmcb_mark_dirty(vmcb02, VMCB_NPT);
 
 	/* Load the nested guest state */
 	if (svm->nested.vmcb12_gpa != svm->nested.last_vmcb12_gpa) {
-- 
2.51.0.470.ga7dc726c21-goog