virtio: Use spin_lock_irqsave/restore for virtio-pci

virtio-pci acquires its spin lock in an interrupt context so it's necessary
to use spin_lock_irqsave/restore variants.  This patch fixes guest SMP when
using virtio devices in KVM.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 26f787ddd5ff..59a8f73dec73 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -177,6 +177,7 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
         struct virtio_pci_device *vp_dev = opaque;
         struct virtio_pci_vq_info *info;
         irqreturn_t ret = IRQ_NONE;
+        unsigned long flags;
         u8 isr;
 
         /* reading the ISR has the effect of also clearing it so it's very
@@ -197,12 +198,12 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
                         drv->config_changed(&vp_dev->vdev);
         }
 
-        spin_lock(&vp_dev->lock);
+        spin_lock_irqsave(&vp_dev->lock, flags);
         list_for_each_entry(info, &vp_dev->virtqueues, node) {
                 if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)
                         ret = IRQ_HANDLED;
         }
-        spin_unlock(&vp_dev->lock);
+        spin_unlock_irqrestore(&vp_dev->lock, flags);
 
         return ret;
 }
@@ -214,6 +215,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
         struct virtio_pci_device *vp_dev = to_vp_device(vdev);
         struct virtio_pci_vq_info *info;
         struct virtqueue *vq;
+        unsigned long flags;
         u16 num;
         int err;
 
@@ -255,9 +257,9 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
         vq->priv = info;
         info->vq = vq;
 
-        spin_lock(&vp_dev->lock);
+        spin_lock_irqsave(&vp_dev->lock, flags);
         list_add(&info->node, &vp_dev->virtqueues);
-        spin_unlock(&vp_dev->lock);
+        spin_unlock_irqrestore(&vp_dev->lock, flags);
 
         return vq;
 
@@ -274,10 +276,11 @@ static void vp_del_vq(struct virtqueue *vq)
 {
         struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
         struct virtio_pci_vq_info *info = vq->priv;
+        unsigned long flags;
 
-        spin_lock(&vp_dev->lock);
+        spin_lock_irqsave(&vp_dev->lock, flags);
         list_del(&info->node);
-        spin_unlock(&vp_dev->lock);
+        spin_unlock_irqrestore(&vp_dev->lock, flags);
 
         vring_del_virtqueue(vq);