Patch "KVM: arm/arm64: Fix spinlock acquisition in vgic_set_owner" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

KVM: arm/arm64: Fix spinlock acquisition in vgic_set_owner

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kvm-arm-arm64-fix-spinlock-acquisition-in-vgic_set_owner.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Marc Zyngier <[email protected]>
Date: Thu, 30 Nov 2017 17:00:30 +0000
Subject: KVM: arm/arm64: Fix spinlock acquisition in vgic_set_owner

From: Marc Zyngier <[email protected]>

[ Upstream commit 7465894e90e5a47e0e52aa5f1f708653fc40020f ]

vgic_set_owner acquires the irq lock without disabling interrupts, resulting in a lockdep splat (an interrupt could fire and result in the same lock being taken if the same virtual irq is to be injected).

In practice, it is almost impossible to trigger this bug, but better safe than sorry. Convert the lock acquisition to a spin_lock_irqsave() and keep lockdep happy.

---
 virt/kvm/arm/vgic/vgic.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

@@ -454,6 +454,7 @@ int kvm_vgic_unmap_phys_irq(struct kvm_v
 int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner)
 {
 	struct vgic_irq *irq;
+	unsigned long flags;
 	int ret = 0;
 
 	if (!vgic_initialized(vcpu->kvm))

@@ -464,12 +465,12 @@ int kvm_vgic_set_owner(struct kvm_vcpu *
 		return -EINVAL;
 
 	irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
-	spin_lock(&irq->irq_lock);
+	spin_lock_irqsave(&irq->irq_lock, flags);
 	if (irq->owner && irq->owner != owner)
 		ret = -EEXIST;
 	else
 		irq->owner = owner;
-	spin_unlock(&irq->irq_lock);
+	spin_unlock_irqrestore(&irq->irq_lock, flags);
 
 	return ret;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/arm-dts-fix-omap4-hang-with-gps-connected-to-usb-by-using-wakeupgen.patch queue-4.14/kvm-arm-don-t-treat-unavailable-hyp-mode-as-an-error.patch queue-4.14/kvm-arm-arm64-fix-spinlock-acquisition-in-vgic_set_owner.patch