Linux Virtualization - Mar 2008 - [PATCH 1/4] virtio: Use spin_lock_irqsave/restore for virtio-pci

From: Anthony Liguori <aliguori at us.ibm.com>

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 at us.ibm.com>
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
---
 drivers/virtio/virtio_pci.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 26f787d..59a8f73 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);

From: Jeremy Katz <katzj at redhat.com>

Fix up so that the virtio_blk devices in sysfs link correctly to their
block device.  This then allows them to be detected by hal, etc

Signed-off-by: Jeremy Katz <katzj at redhat.com>
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
---
 drivers/block/virtio_blk.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 3b1a68d..0cfbe8c 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -238,6 +238,7 @@ static int virtblk_probe(struct virtio_device *vdev)
 	vblk->disk->first_minor = index_to_minor(index);
 	vblk->disk->private_data = vblk;
 	vblk->disk->fops = &virtblk_fops;
+	vblk->disk->driverfs_dev = &vdev->dev;
 	index++;
 
 	/* If barriers are supported, tell block layer that queue is ordered */

If the host asks for a huge target towards_target() can overflow, and
we up oops as we try to release more pages than we have.  The simple
fix is to use a 64-bit value.

Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
---
 drivers/virtio/virtio_balloon.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -r fd0c80dbbd95 drivers/virtio/virtio_balloon.c
--- a/drivers/virtio/virtio_balloon.c	Tue Mar 11 09:21:00 2008 +1100
+++ b/drivers/virtio/virtio_balloon.c	Tue Mar 11 11:25:52 2008 +1100
@@ -152,7 +152,7 @@ static void virtballoon_changed(struct v
 	wake_up(&vb->config_change);
 }
 
-static inline int towards_target(struct virtio_balloon *vb)
+static inline s64 towards_target(struct virtio_balloon *vb)
 {
 	u32 v;
 	__virtio_config_val(vb->vdev,
@@ -176,7 +183,7 @@ static int balloon(void *_vballoon)
 
 	set_freezable();
 	while (!kthread_should_stop()) {
-		int diff;
+		s64 diff;
 
 		try_to_freeze();
 		wait_event_interruptible(vb->config_change,

From: "Amit Shah" <amitshah at gmx.net>

Add a new poll_controller handler that the netpoll interface needs.

This enables netconsole logging from a kvm guest over the virtio
net interface.

Signed-off-by: Amit Shah <amitshah at gmx.net>
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
---
 drivers/net/virtio_net.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -294,6 +294,15 @@ again:
 	return 0;
 }
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+static void virtnet_netpoll(struct net_device *dev)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+
+	napi_schedule(&vi->napi);
+}
+#endif
+
 static int virtnet_open(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
@@ -336,6 +345,9 @@ static int virtnet_probe(struct virtio_d
 	dev->stop = virtnet_close;
 	dev->hard_start_xmit = start_xmit;
 	dev->features = NETIF_F_HIGHDMA;
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	dev->poll_controller = virtnet_netpoll;
+#endif
 	SET_NETDEV_DEV(dev, &vdev->dev);
 
 	/* Do we support "hardware" checksums? */