linux-kernel - [PATCH 1/2] KVM: SVM: Mark VMCB_PERM

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Message-ID: <20250922162935.621409-2-jmattson@google.com>
Date: Mon, 22 Sep 2025 09:29:22 -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>, Matteo Rizzo <matteorizzo@...gle.com>
Subject: [PATCH 1/2] KVM: SVM: Mark VMCB_PERM_MAP as dirty on nested VMRUN

Mark the VMCB_PERM_MAP bit as dirty in nested_vmcb02_prepare_control()
on every nested VMRUN.

If L1 changes MSR interception (INTERCEPT_MSR_PROT) between two VMRUN
instructions on the same L1 vCPU, the msrpm_base_pa in the associated
vmcb02 will change, and the VMCB_PERM_MAP clean bit should be cleared.

Fixes: 4bb170a5430b ("KVM: nSVM: do not mark all VMCB02 fields dirty on nested vmexit")
Reported-by: Matteo Rizzo <matteorizzo@...gle.com>
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 b7fd2e869998..177a9764fb64 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -744,6 +744,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm,
 	vmcb02->control.nested_ctl = vmcb01->control.nested_ctl;
 	vmcb02->control.iopm_base_pa = vmcb01->control.iopm_base_pa;
 	vmcb02->control.msrpm_base_pa = vmcb01->control.msrpm_base_pa;
+	vmcb_mark_dirty(vmcb02, VMCB_PERM_MAP);
 
 	/*
 	 * Stash vmcb02's counter if the guest hasn't moved past the guilty
-- 
2.51.0.470.ga7dc726c21-goog