FAILED: patch "[PATCH] KVM: SVM: Initialize AVIC VMCB fields if AVIC is enabled with" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 3989a6d036c8ec82c0de3614bed23a1dacd45de5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026031620-pediatric-distant-133b@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 3989a6d036c8ec82c0de3614bed23a1dacd45de5 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <[email protected]>
Date: Tue, 3 Feb 2026 11:07:09 -0800
Subject: [PATCH] KVM: SVM: Initialize AVIC VMCB fields if AVIC is enabled with
in-kernel APIC

Initialize all per-vCPU AVIC control fields in the VMCB if AVIC is enabled in KVM and the VM has an in-kernel local APIC, i.e. if it's _possible_ the vCPU could activate AVIC at any point in its lifecycle. Configuring the VMCB if and only if AVIC is active "works" purely because of optimizations in kvm_create_lapic() to speculatively set apicv_active if AVIC is enabled *and* to defer updates until the first KVM_RUN. In quotes because KVM likely won't do the right thing if kvm_apicv_activated() is false, i.e. if a vCPU is created while APICv is inhibited at the VM level for whatever reason. E.g. if the inhibit is *removed* before KVM_REQ_APICV_UPDATE is handled in KVM_RUN, then __kvm_vcpu_update_apicv() will elide calls to vendor code due to seeing "apicv_active == activate".

Cleaning up the initialization code will also allow fixing a bug where KVM incorrectly leaves CR8 interception enabled when AVIC is activated without creating a mess with respect to whether AVIC is activated or not.

index f92214b1a938..44e07c27b190 100644
@@ -368,7 +368,7 @@ void avic_init_vmcb(struct vcpu_svm *svm, struct vmcb *vmcb)
 	vmcb->control.avic_physical_id = __sme_set(__pa(kvm_svm->avic_physical_id_table));
 	vmcb->control.avic_vapic_bar = APIC_DEFAULT_PHYS_BASE;
 
-	if (kvm_apicv_activated(svm->vcpu.kvm))
+	if (kvm_vcpu_apicv_active(&svm->vcpu))
 		avic_activate_vmcb(svm);
 	else
 		avic_deactivate_vmcb(svm);

index 8f8bc863e214..7806321c37bc 100644
@@ -1189,7 +1189,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu, bool init_event)
 	if (guest_cpu_cap_has(vcpu, X86_FEATURE_ERAPS))
 		svm->vmcb->control.erap_ctl |= ERAP_CONTROL_ALLOW_LARGER_RAP;
 
-	if (kvm_vcpu_apicv_active(vcpu))
+	if (enable_apicv && irqchip_in_kernel(vcpu->kvm))
 		avic_init_vmcb(svm, vmcb);
 
 	if (vnmi)

From: Sean Christopherson <[email protected]>

[ Upstream commit 3989a6d036c8ec82c0de3614bed23a1dacd45de5 ]

Initialize all per-vCPU AVIC control fields in the VMCB if AVIC is enabled in KVM and the VM has an in-kernel local APIC, i.e. if it's _possible_ the vCPU could activate AVIC at any point in its lifecycle. Configuring the VMCB if and only if AVIC is active "works" purely because of optimizations in kvm_create_lapic() to speculatively set apicv_active if AVIC is enabled *and* to defer updates until the first KVM_RUN. In quotes because KVM likely won't do the right thing if kvm_apicv_activated() is false, i.e. if a vCPU is created while APICv is inhibited at the VM level for whatever reason. E.g. if the inhibit is *removed* before KVM_REQ_APICV_UPDATE is handled in KVM_RUN, then __kvm_vcpu_update_apicv() will elide calls to vendor code due to seeing "apicv_active == activate".

Cleaning up the initialization code will also allow fixing a bug where KVM incorrectly leaves CR8 interception enabled when AVIC is activated without creating a mess with respect to whether AVIC is activated or not.

---
 arch/x86/kvm/svm/avic.c | 2 +-
 arch/x86/kvm/svm/svm.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

index 4bb2fbe6676a1..7ed416dcb89c6 100644
@@ -199,7 +199,7 @@ void avic_init_vmcb(struct vcpu_svm *svm)
 	vmcb->control.avic_physical_id |= AVIC_MAX_PHYSICAL_ID_COUNT;
 	vmcb->control.avic_vapic_bar = APIC_DEFAULT_PHYS_BASE & VMCB_AVIC_APIC_BAR_MASK;
 
-	if (kvm_apicv_activated(svm->vcpu.kvm))
+	if (kvm_vcpu_apicv_active(&svm->vcpu))
 		vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
 	else
 		vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;

index 1687b74a1a4d8..02346fcce5d8a 100644
@@ -1299,7 +1299,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
 	if (boot_cpu_has(X86_FEATURE_V_SPEC_CTRL))
 		set_msr_interception(vcpu, svm->msrpm, MSR_IA32_SPEC_CTRL, 1, 1);
 
-	if (kvm_vcpu_apicv_active(vcpu))
+	if (enable_apicv && irqchip_in_kernel(vcpu->kvm))
 		avic_init_vmcb(svm);
 
 	if (vgif) {

2.51.0