FAILED: patch "[PATCH] KVM: SVM: Use the active VMCB's MSR bitmap when checking if" failed to apply to 6.18-stable tree

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 9e06bbb9ade7cdf28d4a3b5b14e5812881c8df85
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026100544-compile-overact-e445@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9e06bbb9ade7cdf28d4a3b5b14e5812881c8df85 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <[email protected]>
Date: Wed, 26 Aug 2026 12:58:33 -0700
Subject: [PATCH] KVM: SVM: Use the active VMCB's MSR bitmap when checking if
MSR is intercepted

Use the MSR permission bitmap of the active VMCB instead of assuming that KVM is always using vmcb02's bitmap when L2 is active, as KVM uses msrpm02 if and only if L1 wants to intercept MSR accesses, i.e. if and only if KVM needs to merge msprm01 with msrpm12.

Don't bother tracking the virtual address of the bitmap that's being used, as __va() is cheap on x86, and caching the virtual address would introduce yet another source of potentially stale information.

Message-ID: <[email protected]>

index f4f488328ea4..fe0cba4731b2 100644
@@ -673,16 +673,7 @@ static void clr_dr_intercepts(struct vcpu_svm *svm)
 
 static bool msr_write_intercepted(struct vcpu_svm *svm, u32 msr)
 {
-	/*
-	 * For non-nested case:
-	 * If the L01 MSR bitmap does not intercept the MSR, then we need to
-	 * save it.
-	 *
-	 * For nested case:
-	 * If the L02 MSR bitmap does not intercept the MSR, then we need to
-	 * save it.
-	 */
-	void *msrpm = is_guest_mode(&svm->vcpu) ? svm->nested.msrpm : svm->msrpm;
+	void *msrpm = __va(__sme_clr(svm->vmcb->control.msrpm_base_pa));
 
 	return svm_test_msr_bitmap_write(msrpm, msr);
 }

From: Sean Christopherson <[email protected]>

[ Upstream commit 9e06bbb9ade7cdf28d4a3b5b14e5812881c8df85 ]

Use the MSR permission bitmap of the active VMCB instead of assuming that KVM is always using vmcb02's bitmap when L2 is active, as KVM uses msrpm02 if and only if L1 wants to intercept MSR accesses, i.e. if and only if KVM needs to merge msprm01 with msrpm12.

Don't bother tracking the virtual address of the bitmap that's being used, as __va() is cheap on x86, and caching the virtual address would introduce yet another source of potentially stale information.

Message-ID: <[email protected]>

---
 arch/x86/kvm/svm/svm.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

index a24a6871b6936..ed1aa9b77c6a7 100644
@@ -654,17 +654,7 @@ static void clr_dr_intercepts(struct vcpu_svm *svm)
 
 static bool msr_write_intercepted(struct kvm_vcpu *vcpu, u32 msr)
 {
-	/*
-	 * For non-nested case:
-	 * If the L01 MSR bitmap does not intercept the MSR, then we need to
-	 * save it.
-	 *
-	 * For nested case:
-	 * If the L02 MSR bitmap does not intercept the MSR, then we need to
-	 * save it.
-	 */
-	void *msrpm = is_guest_mode(vcpu) ? to_svm(vcpu)->nested.msrpm :
-					    to_svm(vcpu)->msrpm;
+	void *msrpm = __va(__sme_clr(to_svm(vcpu)->vmcb->control.msrpm_base_pa));
 
 	return svm_test_msr_bitmap_write(msrpm, msr);
 }

2.53.0