[PATCH 1/2] KVM: SVM: Mark VMCB_PERM_MAP as dirty on nested VMRUN

From: Jim Mattson

Date: Mon Sep 22 2025 - 12:29:46 EST


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@xxxxxxxxxx>
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
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