[PATCH v2 3/5] KVM: arm64: vgic-v3: Unregister redistributors before freeing regions

[Karl Mehltretter]

vgic_unregister_redist_iodev() uses rdreg to return its region slot. During
VM teardown, kvm_vgic_destroy() frees the regions before unregistering
their iodevs, so vgic_v3_free_redist_region() must first clear every rdreg
pointer.

Unregister the iodevs before kvm_vgic_dist_destroy(), while the regions are
still alive. Temporarily drop config_lock because
vgic_unregister_redist_iodev() takes it; slots_lock remains held for the
MMIO bus updates. The region destructor no longer needs the vCPU scan.

Suggested-by: Marc Zyngier <maz at kernel.org>
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Karl Mehltretter <kmehltretter at gmail.com>
---
 arch/arm64/kvm/vgic/vgic-init.c    | 11 +++++++----
 arch/arm64/kvm/vgic/vgic-mmio-v3.c |  9 ---------
 2 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index 0a3df6d3a691..df6d0bdda4a9 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -570,14 +570,17 @@ void kvm_vgic_destroy(struct kvm *kvm)
 	kvm_for_each_vcpu(i, vcpu, kvm)
 		__kvm_vgic_vcpu_destroy(vcpu);
 
+	if (kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) {
+		mutex_unlock(&kvm->arch.config_lock);
+		kvm_for_each_vcpu(i, vcpu, kvm)
+			vgic_unregister_redist_iodev(vcpu);
+		mutex_lock(&kvm->arch.config_lock);
+	}
+
 	kvm_vgic_dist_destroy(kvm);
 
 	mutex_unlock(&kvm->arch.config_lock);
 
-	if (kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
-		kvm_for_each_vcpu(i, vcpu, kvm)
-			vgic_unregister_redist_iodev(vcpu);
-
 	mutex_unlock(&kvm->slots_lock);
 }
 
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index 331d203acb43..77a611564f8e 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -967,17 +967,8 @@ static int vgic_v3_alloc_redist_region(struct kvm *kvm, uint32_t index,
 
 void vgic_v3_free_redist_region(struct kvm *kvm, struct vgic_redist_region *rdreg)
 {
-	struct kvm_vcpu *vcpu;
-	unsigned long c;
-
 	lockdep_assert_held(&kvm->arch.config_lock);
 
-	/* Garbage collect the region */
-	kvm_for_each_vcpu(c, vcpu, kvm) {
-		if (vcpu->arch.vgic_cpu.rdreg == rdreg)
-			vcpu->arch.vgic_cpu.rdreg = NULL;
-	}
-
 	list_del(&rdreg->list);
 	kfree(rdreg);
 }
-- 
2.39.5 (Apple Git-154)