[PATCH 5.15.y] KVM: SVM: Mark VMCB_NPT as dirty on nested VMRUN

[Sasha Levin <sashal@kernel.org>]

From: Jim Mattson <jmattson@google.com>

[ Upstream commit 7c8b465a1c91f674655ea9cec5083744ec5f796a ]

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")
Cc: stable@vger.kernel.org
Signed-off-by: Jim Mattson <jmattson@google.com>
Link: https://lore.kernel.org/r/20250922162935.621409-3-jmattson@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
[ adapted vmcb02 local variable to svm->vmcb direct access pattern ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 c24d7860bd53..5f9f14eb61c4 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -456,6 +456,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
 	bool new_vmcb12 = false;
 
 	nested_vmcb02_compute_g_pat(svm);
+	vmcb_mark_dirty(svm->vmcb, VMCB_NPT);
 
 	/* Load the nested guest state */
 	if (svm->nested.vmcb12_gpa != svm->nested.last_vmcb12_gpa) {
-- 
2.51.0