From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [PATCH] KVM: arm/arm64: Fix spinlock acquisition in vgic_set_owner Date: Fri, 1 Dec 2017 08:55:07 +0100 Message-ID: <20171201075507.GA4218@cbox> References: <20171130170030.29827-1-marc.zyngier@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu To: Marc Zyngier Return-path: Content-Disposition: inline In-Reply-To: <20171130170030.29827-1-marc.zyngier@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org On Thu, Nov 30, 2017 at 05:00:30PM +0000, Marc Zyngier wrote: > 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. > > Reported-by: James Morse > Signed-off-by: Marc Zyngier Applied, thanks. -Christoffer > --- > virt/kvm/arm/vgic/vgic.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c > index b168a328a9e0..8d863e6405a5 100644 > --- a/virt/kvm/arm/vgic/vgic.c > +++ b/virt/kvm/arm/vgic/vgic.c > @@ -492,6 +492,7 @@ int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int vintid) > 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)) > @@ -502,12 +503,12 @@ int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner) > 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; > } > -- > 2.11.0 >