[PATCH 1/8] virtio: add request_vqs/free_vqs operations

[PATCH 1/8] virtio: add request_vqs/free_vqs operations

[Michael S. Tsirkin]

This adds 2 new optional virtio operations: request_vqs/free_vqs. They will be
used for MSI support, because MSI needs to know the total number of vectors
upfront.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/linux/virtio_config.h |   35 +++++++++++++++++++++++++++++++++++
 1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index bf8ec28..e935670 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -49,6 +49,15 @@
  * @set_status: write the status byte
  *	vdev: the virtio_device
  *	status: the new status byte
+ * @request_vqs: request the specified number of virtqueues
+ *	vdev: the virtio_device
+ *	max_vqs: the max number of virtqueues we want
+ *      If supplied, must call before any virtqueues are instantiated.
+ *      To modify the max number of virtqueues after request_vqs has been
+ *      called, call free_vqs and then request_vqs with a new value.
+ * @free_vqs: cleanup resources allocated by request_vqs
+ *	vdev: the virtio_device
+ *      If supplied, must call after all virtqueues have been deleted.
  * @reset: reset the device
  *	vdev: the virtio device
  *	After this, status and feature negotiation must be done again
@@ -75,6 +84,8 @@ struct virtio_config_ops
 	u8 (*get_status)(struct virtio_device *vdev);
 	void (*set_status)(struct virtio_device *vdev, u8 status);
 	void (*reset)(struct virtio_device *vdev);
+	int (*request_vqs)(struct virtio_device *vdev, unsigned max_vqs);
+	void (*free_vqs)(struct virtio_device *vdev);
 	struct virtqueue *(*find_vq)(struct virtio_device *vdev,
 				     unsigned index,
 				     void (*callback)(struct virtqueue *));
@@ -126,5 +137,29 @@ static inline int virtio_config_buf(struct virtio_device *vdev,
 	vdev->config->get(vdev, offset, buf, len);
 	return 0;
 }
+
+/**
+ * virtio_request_vqs: request the specified number of virtqueues
+ * @vdev: the virtio_device
+ * @max_vqs: the max number of virtqueues we want
+ *
+ * For details, see documentation for request_vqs above. */
+static inline int virtio_request_vqs(struct virtio_device *vdev,
+				     unsigned max_vqs)
+{
+	return vdev->config->request_vqs ?
+		vdev->config->request_vqs(vdev, max_vqs) : 0;
+}
+
+/**
+ * free_vqs: cleanup resources allocated by virtio_request_vqs
+ * @vdev: the virtio_device
+ *
+ * For details, see documentation for free_vqs above. */
+static inline void virtio_free_vqs(struct virtio_device *vdev)
+{
+	if (vdev->config->free_vqs)
+		vdev->config->free_vqs(vdev);
+}
 #endif /* __KERNEL__ */
 #endif /* _LINUX_VIRTIO_CONFIG_H */
-- 
1.6.0.6

Re: [PATCH 1/8] virtio: add request_vqs/free_vqs operations

[Rusty Russell]

On Mon, 27 Apr 2009 10:01:53 pm Michael S. Tsirkin wrote:
> This adds 2 new optional virtio operations: request_vqs/free_vqs. They will be
> used for MSI support, because MSI needs to know the total number of vectors
> upfront.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Hi Michael,

  Thanks for this work!  But this interface is horrible.  Either probe for the
number of vqs in virtio_pci, or change find_vq to

	int (*find_vqs)(struct virtio_device *, unsigned max,
						     struct virtqueue *vqs[]);

Thanks,
Rusty.

Re: [PATCH 1/8] virtio: add request_vqs/free_vqs operations

[Rusty Russell]

On Mon, 27 Apr 2009 10:01:53 pm Michael S. Tsirkin wrote:
> This adds 2 new optional virtio operations: request_vqs/free_vqs. They will be
> used for MSI support, because MSI needs to know the total number of vectors
> upfront.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Hi Michael,

  Thanks for this work!  But this interface is horrible.  Either probe for the
number of vqs in virtio_pci, or change find_vq to

	int (*find_vqs)(struct virtio_device *, unsigned max,
						     struct virtqueue *vqs[]);

Thanks,
Rusty.

Re: [PATCH 1/8] virtio: add request_vqs/free_vqs operations

[Michael S. Tsirkin]

On Mon, May 04, 2009 at 09:02:20PM +0930, Rusty Russell wrote:
> On Mon, 27 Apr 2009 10:01:53 pm Michael S. Tsirkin wrote:
> > This adds 2 new optional virtio operations: request_vqs/free_vqs. They will be
> > used for MSI support, because MSI needs to know the total number of vectors
> > upfront.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> 
> Hi Michael,

Hi Rusty,

>   Thanks for this work!  But this interface is horrible.  Either probe for the
> number of vqs in virtio_pci, or change find_vq to
> 
> 	int (*find_vqs)(struct virtio_device *, unsigned max,
> 						     struct virtqueue *vqs[]);

I'm happier with the later option: it's easy for a host to expose
support for a very large number of vqs, and I don't want them to
waste resources if guest does not use them.

Thanks for the feedback!

> Thanks,
> Rusty.

-- 
MST

Re: [PATCH 1/8] virtio: add request_vqs/free_vqs operations

[Michael S. Tsirkin]

On Mon, May 04, 2009 at 09:02:20PM +0930, Rusty Russell wrote:
> On Mon, 27 Apr 2009 10:01:53 pm Michael S. Tsirkin wrote:
> > This adds 2 new optional virtio operations: request_vqs/free_vqs. They will be
> > used for MSI support, because MSI needs to know the total number of vectors
> > upfront.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> 
> Hi Michael,

Hi Rusty,

>   Thanks for this work!  But this interface is horrible.  Either probe for the
> number of vqs in virtio_pci, or change find_vq to
> 
> 	int (*find_vqs)(struct virtio_device *, unsigned max,
> 						     struct virtqueue *vqs[]);

I'm happier with the later option: it's easy for a host to expose
support for a very large number of vqs, and I don't want them to
waste resources if guest does not use them.

Thanks for the feedback!

> Thanks,
> Rusty.

-- 
MST

[PATCH 1/8] virtio: add request_vqs/free_vqs operations

[Michael S. Tsirkin]

This adds 2 new optional virtio operations: request_vqs/free_vqs. They will be
used for MSI support, because MSI needs to know the total number of vectors
upfront.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/linux/virtio_config.h |   35 +++++++++++++++++++++++++++++++++++
 1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index bf8ec28..e935670 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -49,6 +49,15 @@
  * @set_status: write the status byte
  *	vdev: the virtio_device
  *	status: the new status byte
+ * @request_vqs: request the specified number of virtqueues
+ *	vdev: the virtio_device
+ *	max_vqs: the max number of virtqueues we want
+ *      If supplied, must call before any virtqueues are instantiated.
+ *      To modify the max number of virtqueues after request_vqs has been
+ *      called, call free_vqs and then request_vqs with a new value.
+ * @free_vqs: cleanup resources allocated by request_vqs
+ *	vdev: the virtio_device
+ *      If supplied, must call after all virtqueues have been deleted.
  * @reset: reset the device
  *	vdev: the virtio device
  *	After this, status and feature negotiation must be done again
@@ -75,6 +84,8 @@ struct virtio_config_ops
 	u8 (*get_status)(struct virtio_device *vdev);
 	void (*set_status)(struct virtio_device *vdev, u8 status);
 	void (*reset)(struct virtio_device *vdev);
+	int (*request_vqs)(struct virtio_device *vdev, unsigned max_vqs);
+	void (*free_vqs)(struct virtio_device *vdev);
 	struct virtqueue *(*find_vq)(struct virtio_device *vdev,
 				     unsigned index,
 				     void (*callback)(struct virtqueue *));
@@ -126,5 +137,29 @@ static inline int virtio_config_buf(struct virtio_device *vdev,
 	vdev->config->get(vdev, offset, buf, len);
 	return 0;
 }
+
+/**
+ * virtio_request_vqs: request the specified number of virtqueues
+ * @vdev: the virtio_device
+ * @max_vqs: the max number of virtqueues we want
+ *
+ * For details, see documentation for request_vqs above. */
+static inline int virtio_request_vqs(struct virtio_device *vdev,
+				     unsigned max_vqs)
+{
+	return vdev->config->request_vqs ?
+		vdev->config->request_vqs(vdev, max_vqs) : 0;
+}
+
+/**
+ * free_vqs: cleanup resources allocated by virtio_request_vqs
+ * @vdev: the virtio_device
+ *
+ * For details, see documentation for free_vqs above. */
+static inline void virtio_free_vqs(struct virtio_device *vdev)
+{
+	if (vdev->config->free_vqs)
+		vdev->config->free_vqs(vdev);
+}
 #endif /* __KERNEL__ */
 #endif /* _LINUX_VIRTIO_CONFIG_H */
-- 
1.6.0.6

[PATCH 2/8] virtio_blk: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio_blk.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/block/virtio_blk.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 5d34764..523eddc 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -224,10 +224,14 @@ static int virtblk_probe(struct virtio_device *vdev)
 	sg_init_table(vblk->sg, vblk->sg_elems);
 
 	/* We expect one virtqueue, for output. */
+	err = virtio_request_vqs(vdev, 1);
+	if (err)
+		goto out_free_vblk;
+
 	vblk->vq = vdev->config->find_vq(vdev, 0, blk_done);
 	if (IS_ERR(vblk->vq)) {
 		err = PTR_ERR(vblk->vq);
-		goto out_free_vblk;
+		goto out_free_vqs;
 	}
 
 	vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
@@ -324,6 +328,8 @@ out_mempool:
 	mempool_destroy(vblk->pool);
 out_free_vq:
 	vdev->config->del_vq(vblk->vq);
+out_free_vqs:
+	virtio_free_vqs(vdev);
 out_free_vblk:
 	kfree(vblk);
 out:
@@ -345,6 +351,7 @@ static void virtblk_remove(struct virtio_device *vdev)
 	put_disk(vblk->disk);
 	mempool_destroy(vblk->pool);
 	vdev->config->del_vq(vblk->vq);
+	virtio_free_vqs(vdev);
 	kfree(vblk);
 }
 
-- 
1.6.0.6

[PATCH 2/8] virtio_blk: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio_blk.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/block/virtio_blk.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 5d34764..523eddc 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -224,10 +224,14 @@ static int virtblk_probe(struct virtio_device *vdev)
 	sg_init_table(vblk->sg, vblk->sg_elems);
 
 	/* We expect one virtqueue, for output. */
+	err = virtio_request_vqs(vdev, 1);
+	if (err)
+		goto out_free_vblk;
+
 	vblk->vq = vdev->config->find_vq(vdev, 0, blk_done);
 	if (IS_ERR(vblk->vq)) {
 		err = PTR_ERR(vblk->vq);
-		goto out_free_vblk;
+		goto out_free_vqs;
 	}
 
 	vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
@@ -324,6 +328,8 @@ out_mempool:
 	mempool_destroy(vblk->pool);
 out_free_vq:
 	vdev->config->del_vq(vblk->vq);
+out_free_vqs:
+	virtio_free_vqs(vdev);
 out_free_vblk:
 	kfree(vblk);
 out:
@@ -345,6 +351,7 @@ static void virtblk_remove(struct virtio_device *vdev)
 	put_disk(vblk->disk);
 	mempool_destroy(vblk->pool);
 	vdev->config->del_vq(vblk->vq);
+	virtio_free_vqs(vdev);
 	kfree(vblk);
 }
 
-- 
1.6.0.6

[PATCH 3/8] virtio-rng: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio-rng.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/char/hw_random/virtio-rng.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index d0e563e..d43a6cd 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -94,13 +94,20 @@ static int virtrng_probe(struct virtio_device *vdev)
 	int err;
 
 	/* We expect a single virtqueue. */
+	err = virtio_request_vqs(vdev, 1);
+	if (err)
+		return err;
+
 	vq = vdev->config->find_vq(vdev, 0, random_recv_done);
-	if (IS_ERR(vq))
+	if (IS_ERR(vq)) {
+		virtio_free_vqs(vdev);
 		return PTR_ERR(vq);
+	}
 
 	err = hwrng_register(&virtio_hwrng);
 	if (err) {
 		vdev->config->del_vq(vq);
+		virtio_free_vqs(vdev);
 		return err;
 	}
 
@@ -113,6 +120,7 @@ static void virtrng_remove(struct virtio_device *vdev)
 	vdev->config->reset(vdev);
 	hwrng_unregister(&virtio_hwrng);
 	vdev->config->del_vq(vq);
+	virtio_free_vqs(vdev);
 }
 
 static struct virtio_device_id id_table[] = {
-- 
1.6.0.6

[PATCH 3/8] virtio-rng: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio-rng.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/char/hw_random/virtio-rng.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index d0e563e..d43a6cd 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -94,13 +94,20 @@ static int virtrng_probe(struct virtio_device *vdev)
 	int err;
 
 	/* We expect a single virtqueue. */
+	err = virtio_request_vqs(vdev, 1);
+	if (err)
+		return err;
+
 	vq = vdev->config->find_vq(vdev, 0, random_recv_done);
-	if (IS_ERR(vq))
+	if (IS_ERR(vq)) {
+		virtio_free_vqs(vdev);
 		return PTR_ERR(vq);
+	}
 
 	err = hwrng_register(&virtio_hwrng);
 	if (err) {
 		vdev->config->del_vq(vq);
+		virtio_free_vqs(vdev);
 		return err;
 	}
 
@@ -113,6 +120,7 @@ static void virtrng_remove(struct virtio_device *vdev)
 	vdev->config->reset(vdev);
 	hwrng_unregister(&virtio_hwrng);
 	vdev->config->del_vq(vq);
+	virtio_free_vqs(vdev);
 }
 
 static struct virtio_device_id id_table[] = {
-- 
1.6.0.6

[PATCH 4/8] virtio_console: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio_console.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/char/virtio_console.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index ff6f5a4..78c503f 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -199,13 +199,17 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
 		goto fail;
 	}
 
+	err = virtio_request_vqs(vdev, 2);
+	if (err)
+		goto free;
+
 	/* Find the input queue. */
 	/* FIXME: This is why we want to wean off hvc: we do nothing
 	 * when input comes in. */
 	in_vq = vdev->config->find_vq(vdev, 0, hvc_handle_input);
 	if (IS_ERR(in_vq)) {
 		err = PTR_ERR(in_vq);
-		goto free;
+		goto free_vqs;
 	}
 
 	out_vq = vdev->config->find_vq(vdev, 1, NULL);
@@ -244,6 +248,8 @@ free_out_vq:
 	vdev->config->del_vq(out_vq);
 free_in_vq:
 	vdev->config->del_vq(in_vq);
+free_vqs:
+	virtio_free_vqs(vdev);
 free:
 	kfree(inbuf);
 fail:
-- 
1.6.0.6

[PATCH 4/8] virtio_console: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio_console.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/char/virtio_console.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index ff6f5a4..78c503f 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -199,13 +199,17 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
 		goto fail;
 	}
 
+	err = virtio_request_vqs(vdev, 2);
+	if (err)
+		goto free;
+
 	/* Find the input queue. */
 	/* FIXME: This is why we want to wean off hvc: we do nothing
 	 * when input comes in. */
 	in_vq = vdev->config->find_vq(vdev, 0, hvc_handle_input);
 	if (IS_ERR(in_vq)) {
 		err = PTR_ERR(in_vq);
-		goto free;
+		goto free_vqs;
 	}
 
 	out_vq = vdev->config->find_vq(vdev, 1, NULL);
@@ -244,6 +248,8 @@ free_out_vq:
 	vdev->config->del_vq(out_vq);
 free_in_vq:
 	vdev->config->del_vq(in_vq);
+free_vqs:
+	virtio_free_vqs(vdev);
 free:
 	kfree(inbuf);
 fail:
-- 
1.6.0.6

[PATCH 5/8] virtio_net: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio_net.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/net/virtio_net.c |   16 +++++++++++++---
 1 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9c82a39..fbe8a70 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -841,6 +841,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 	int err;
 	struct net_device *dev;
 	struct virtnet_info *vi;
+	bool control_vq;
 
 	/* Allocate ourselves a network device with room for our info */
 	dev = alloc_etherdev(sizeof(struct virtnet_info));
@@ -901,11 +902,17 @@ static int virtnet_probe(struct virtio_device *vdev)
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
 		vi->mergeable_rx_bufs = true;
 
-	/* We expect two virtqueues, receive then send. */
+	/* We expect either two or three virtqueues: receive, send and
+	 * optionally control. */
+	control_vq = virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ);
+	err = virtio_request_vqs(vdev, control_vq ? 3 : 2);
+	if (err)
+		goto free;
+
 	vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
 	if (IS_ERR(vi->rvq)) {
 		err = PTR_ERR(vi->rvq);
-		goto free;
+		goto free_vqs;
 	}
 
 	vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
@@ -914,7 +921,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 		goto free_recv;
 	}
 
-	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ)) {
+	if (control_vq) {
 		vi->cvq = vdev->config->find_vq(vdev, 2, NULL);
 		if (IS_ERR(vi->cvq)) {
 			err = PTR_ERR(vi->svq);
@@ -965,6 +972,8 @@ free_send:
 	vdev->config->del_vq(vi->svq);
 free_recv:
 	vdev->config->del_vq(vi->rvq);
+free_vqs:
+	virtio_free_vqs(vi->vdev);
 free:
 	free_netdev(dev);
 	return err;
@@ -994,6 +1003,7 @@ static void virtnet_remove(struct virtio_device *vdev)
 	vdev->config->del_vq(vi->rvq);
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
 		vdev->config->del_vq(vi->cvq);
+	virtio_free_vqs(vi->vdev);
 	unregister_netdev(vi->dev);
 
 	while (vi->pages)
-- 
1.6.0.6

[PATCH 5/8] virtio_net: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio_net.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/net/virtio_net.c |   16 +++++++++++++---
 1 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9c82a39..fbe8a70 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -841,6 +841,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 	int err;
 	struct net_device *dev;
 	struct virtnet_info *vi;
+	bool control_vq;
 
 	/* Allocate ourselves a network device with room for our info */
 	dev = alloc_etherdev(sizeof(struct virtnet_info));
@@ -901,11 +902,17 @@ static int virtnet_probe(struct virtio_device *vdev)
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
 		vi->mergeable_rx_bufs = true;
 
-	/* We expect two virtqueues, receive then send. */
+	/* We expect either two or three virtqueues: receive, send and
+	 * optionally control. */
+	control_vq = virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ);
+	err = virtio_request_vqs(vdev, control_vq ? 3 : 2);
+	if (err)
+		goto free;
+
 	vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
 	if (IS_ERR(vi->rvq)) {
 		err = PTR_ERR(vi->rvq);
-		goto free;
+		goto free_vqs;
 	}
 
 	vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
@@ -914,7 +921,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 		goto free_recv;
 	}
 
-	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ)) {
+	if (control_vq) {
 		vi->cvq = vdev->config->find_vq(vdev, 2, NULL);
 		if (IS_ERR(vi->cvq)) {
 			err = PTR_ERR(vi->svq);
@@ -965,6 +972,8 @@ free_send:
 	vdev->config->del_vq(vi->svq);
 free_recv:
 	vdev->config->del_vq(vi->rvq);
+free_vqs:
+	virtio_free_vqs(vi->vdev);
 free:
 	free_netdev(dev);
 	return err;
@@ -994,6 +1003,7 @@ static void virtnet_remove(struct virtio_device *vdev)
 	vdev->config->del_vq(vi->rvq);
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
 		vdev->config->del_vq(vi->cvq);
+	virtio_free_vqs(vi->vdev);
 	unregister_netdev(vi->dev);
 
 	while (vi->pages)
-- 
1.6.0.6

[PATCH 6/8] virtio_balloon: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio_balloon.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_balloon.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 5926826..77eac2b 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -217,10 +217,14 @@ static int virtballoon_probe(struct virtio_device *vdev)
 	vb->vdev = vdev;
 
 	/* We expect two virtqueues. */
+	err = virtio_request_vqs(vdev, 2);
+	if (err)
+		goto out_free_vb;
+
 	vb->inflate_vq = vdev->config->find_vq(vdev, 0, balloon_ack);
 	if (IS_ERR(vb->inflate_vq)) {
 		err = PTR_ERR(vb->inflate_vq);
-		goto out_free_vb;
+		goto out_free_vqs;
 	}
 
 	vb->deflate_vq = vdev->config->find_vq(vdev, 1, balloon_ack);
@@ -244,6 +248,8 @@ out_del_deflate_vq:
 	vdev->config->del_vq(vb->deflate_vq);
 out_del_inflate_vq:
 	vdev->config->del_vq(vb->inflate_vq);
+out_free_vqs:
+	virtio_free_vqs(vdev);
 out_free_vb:
 	kfree(vb);
 out:
@@ -265,6 +271,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
 
 	vdev->config->del_vq(vb->deflate_vq);
 	vdev->config->del_vq(vb->inflate_vq);
+	virtio_free_vqs(vdev);
 	kfree(vb);
 }
 
-- 
1.6.0.6

[PATCH 6/8] virtio_balloon: add request_vqs/free_vqs calls

[Michael S. Tsirkin]

Add request_vqs/free_vqs calls to virtio_balloon.
These will be required for MSI support.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_balloon.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 5926826..77eac2b 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -217,10 +217,14 @@ static int virtballoon_probe(struct virtio_device *vdev)
 	vb->vdev = vdev;
 
 	/* We expect two virtqueues. */
+	err = virtio_request_vqs(vdev, 2);
+	if (err)
+		goto out_free_vb;
+
 	vb->inflate_vq = vdev->config->find_vq(vdev, 0, balloon_ack);
 	if (IS_ERR(vb->inflate_vq)) {
 		err = PTR_ERR(vb->inflate_vq);
-		goto out_free_vb;
+		goto out_free_vqs;
 	}
 
 	vb->deflate_vq = vdev->config->find_vq(vdev, 1, balloon_ack);
@@ -244,6 +248,8 @@ out_del_deflate_vq:
 	vdev->config->del_vq(vb->deflate_vq);
 out_del_inflate_vq:
 	vdev->config->del_vq(vb->inflate_vq);
+out_free_vqs:
+	virtio_free_vqs(vdev);
 out_free_vb:
 	kfree(vb);
 out:
@@ -265,6 +271,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
 
 	vdev->config->del_vq(vb->deflate_vq);
 	vdev->config->del_vq(vb->inflate_vq);
+	virtio_free_vqs(vdev);
 	kfree(vb);
 }
 
-- 
1.6.0.6

[PATCH 7/8] virtio_pci: split up vp_interrupt

[Michael S. Tsirkin]

This reorganizes virtio-pci code in vp_interrupt slightly, so that
it's easier to add per-vq MSI support on top.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_pci.c |   45 +++++++++++++++++++++++++++++++++---------
 1 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 330aacb..151538c 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -164,6 +164,37 @@ static void vp_notify(struct virtqueue *vq)
 	iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
 }
 
+/* Handle a configuration change: Tell driver if it wants to know. */
+static irqreturn_t vp_config_changed(int irq, void *opaque)
+{
+	struct virtio_pci_device *vp_dev = opaque;
+	struct virtio_driver *drv;
+	drv = container_of(vp_dev->vdev.dev.driver,
+			   struct virtio_driver, driver);
+
+	if (drv && drv->config_changed)
+		drv->config_changed(&vp_dev->vdev);
+	return IRQ_HANDLED;
+}
+
+/* Notify all virtqueues on an interrupt. */
+static irqreturn_t vp_vring_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;
+
+	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_irqrestore(&vp_dev->lock, flags);
+
+	return ret;
+}
+
 /* A small wrapper to also acknowledge the interrupt when it's handled.
  * I really need an EIO hook for the vring so I can ack the interrupt once we
  * know that we'll be handling the IRQ but before we invoke the callback since
@@ -173,9 +204,6 @@ static void vp_notify(struct virtqueue *vq)
 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
@@ -187,14 +215,11 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
 		return IRQ_NONE;
 
 	/* Configuration change?  Tell driver if it wants to know. */
-	if (isr & VIRTIO_PCI_ISR_CONFIG) {
-		struct virtio_driver *drv;
-		drv = container_of(vp_dev->vdev.dev.driver,
-				   struct virtio_driver, driver);
+	if (isr & VIRTIO_PCI_ISR_CONFIG)
+		vp_config_changed(irq, opaque);
 
-		if (drv && drv->config_changed)
-			drv->config_changed(&vp_dev->vdev);
-	}
+	return vp_vring_interrupt(irq, opaque);
+}
 
 	spin_lock_irqsave(&vp_dev->lock, flags);
 	list_for_each_entry(info, &vp_dev->virtqueues, node) {
-- 
1.6.0.6

[PATCH 7/8] virtio_pci: split up vp_interrupt

[Michael S. Tsirkin]

This reorganizes virtio-pci code in vp_interrupt slightly, so that
it's easier to add per-vq MSI support on top.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_pci.c |   45 +++++++++++++++++++++++++++++++++---------
 1 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 330aacb..151538c 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -164,6 +164,37 @@ static void vp_notify(struct virtqueue *vq)
 	iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
 }
 
+/* Handle a configuration change: Tell driver if it wants to know. */
+static irqreturn_t vp_config_changed(int irq, void *opaque)
+{
+	struct virtio_pci_device *vp_dev = opaque;
+	struct virtio_driver *drv;
+	drv = container_of(vp_dev->vdev.dev.driver,
+			   struct virtio_driver, driver);
+
+	if (drv && drv->config_changed)
+		drv->config_changed(&vp_dev->vdev);
+	return IRQ_HANDLED;
+}
+
+/* Notify all virtqueues on an interrupt. */
+static irqreturn_t vp_vring_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;
+
+	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_irqrestore(&vp_dev->lock, flags);
+
+	return ret;
+}
+
 /* A small wrapper to also acknowledge the interrupt when it's handled.
  * I really need an EIO hook for the vring so I can ack the interrupt once we
  * know that we'll be handling the IRQ but before we invoke the callback since
@@ -173,9 +204,6 @@ static void vp_notify(struct virtqueue *vq)
 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
@@ -187,14 +215,11 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
 		return IRQ_NONE;
 
 	/* Configuration change?  Tell driver if it wants to know. */
-	if (isr & VIRTIO_PCI_ISR_CONFIG) {
-		struct virtio_driver *drv;
-		drv = container_of(vp_dev->vdev.dev.driver,
-				   struct virtio_driver, driver);
+	if (isr & VIRTIO_PCI_ISR_CONFIG)
+		vp_config_changed(irq, opaque);
 
-		if (drv && drv->config_changed)
-			drv->config_changed(&vp_dev->vdev);
-	}
+	return vp_vring_interrupt(irq, opaque);
+}
 
 	spin_lock_irqsave(&vp_dev->lock, flags);
 	list_for_each_entry(info, &vp_dev->virtqueues, node) {
-- 
1.6.0.6

[PATCH 8/8] virtio_pci: optional MSI-X support

[Michael S. Tsirkin]

This implements optional MSI-X support in virtio_pci.
MSI-X is used whenever the host supports at least 2 MSI-X
vectors: 1 for configuration changes and 1 for virtqueues.
Per-virtqueue vectors are allocated if enough vectors
available.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_pci.c |  147 ++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 132 insertions(+), 15 deletions(-)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 151538c..20bdc8c 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -42,8 +42,33 @@ struct virtio_pci_device
 	/* a list of queues so we can dispatch IRQs */
 	spinlock_t lock;
 	struct list_head virtqueues;
+
+	/* MSI-X support */
+	struct msix_entry *msix_entries;
+	/* Name strings for interrupts. This size should be enough,
+	 * and I'm too lazy to allocate each name separately. */
+	char (*msix_names)[256];
+	/* Number of vectors configured at startup (excludes per-virtqueue
+	 * vectors if any) */
+	unsigned msix_preset_vectors;
+	/* Number of per-virtqueue vectors if any. */
+	unsigned msix_per_vq_vectors;
+};
+
+/* Constants for MSI-X */
+/* Use first vector for configuration changes, second and the rest for
+ * virtqueues Thus, we need at least 2 vectors for MSI. */
+enum {
+	VP_MSIX_CONFIG_VECTOR = 0,
+	VP_MSIX_VQ_VECTOR = 1,
+	VP_MSIX_MIN_VECTORS = 2
 };
 
+static inline int vq_vector(int index)
+{
+	return index + VP_MSIX_VQ_VECTOR;
+}
+
 struct virtio_pci_vq_info
 {
 	/* the actual virtqueue */
@@ -221,14 +246,92 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
 	return vp_vring_interrupt(irq, opaque);
 }
 
-	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;
+/* the config->free_vqs() implementation */
+static void vp_free_vqs(struct virtio_device *vdev) {
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	int i;
+
+	for (i = 0; i < vp_dev->msix_preset_vectors; ++i)
+		free_irq(vp_dev->msix_entries[i].vector, vp_dev);
+
+	if (!vp_dev->msix_preset_vectors)
+		free_irq(vp_dev->pci_dev->irq, vp_dev);
+}
+
+/* the config->request_vqs() implementation */
+static int vp_request_vqs(struct virtio_device *vdev, unsigned max_vqs) {
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	const char *name = dev_name(&vp_dev->vdev.dev);
+	unsigned i, vectors;
+	int err = -ENOMEM;
+
+	/* We need at most one vector per queue and one for config changes */
+	vectors = vq_vector(max_vqs);
+	vp_dev->msix_entries = kmalloc(vectors * sizeof *vp_dev->msix_entries,
+				       GFP_KERNEL);
+	if (!vp_dev->msix_entries)
+		goto error_entries;
+	vp_dev->msix_names = kmalloc(vectors * sizeof *vp_dev->msix_names,
+				     GFP_KERNEL);
+	if (!vp_dev->msix_names)
+		goto error_names;
+
+	snprintf(vp_dev->msix_names[VP_MSIX_CONFIG_VECTOR],
+		 sizeof *vp_dev->msix_names, "%s-config", name);
+	for (i = 0; i < max_vqs; ++i)
+		snprintf(vp_dev->msix_names[vq_vector(i)],
+			 sizeof *vp_dev->msix_names, "%s-vq-%d", name, i);
+
+	vp_dev->msix_preset_vectors = 1;
+	vp_dev->msix_per_vq_vectors = max_vqs;
+	for (;;) {
+		err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries,
+				      vectors);
+		/* Error out if not enough vectors */
+		if (err > 0 && err < VP_MSIX_MIN_VECTORS)
+			err = -EBUSY;
+		if (err <= 0)
+			break;
+		/* Not enough vectors for all queues. Retry, disabling
+		 * per-queue interrupts */
+		vectors = VP_MSIX_MIN_VECTORS;
+		vp_dev->msix_preset_vectors = VP_MSIX_MIN_VECTORS;
+		vp_dev->msix_per_vq_vectors = 0;
+		snprintf(vp_dev->msix_names[VP_MSIX_VQ_VECTOR],
+			 sizeof *vp_dev->msix_names, "%s-vq", name);
 	}
-	spin_unlock_irqrestore(&vp_dev->lock, flags);
 
-	return ret;
+	if (err) {
+		/* Can't allocate enough MSI-X vectors, use regular interrupt */
+		vp_dev->msix_preset_vectors = 0;
+		vp_dev->msix_per_vq_vectors = 0;
+		/* Register a handler for the queue with the PCI device's
+		 * interrupt */
+		err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
+				  IRQF_SHARED, name, vp_dev);
+		if (err)
+			goto error_irq;
+	}
+	for (i = 0; i < vp_dev->msix_preset_vectors; ++i) {
+		err = request_irq(vp_dev->msix_entries[i].vector,
+				  i == VP_MSIX_CONFIG_VECTOR ?
+				  vp_config_changed : vp_vring_interrupt,
+				  0, vp_dev->msix_names[i], vp_dev);
+		if (err) {
+			/* Set msix_preset_vectors so that only vectors we
+			 * already allocated will be freed by vp_free_vqs. */
+			vp_dev->msix_preset_vectors = i;
+			goto error_irq;
+		}
+	}
+	return 0;
+error_irq:
+	vp_free_vqs(vdev);
+	kfree(vp_dev->msix_names);
+error_names:
+	kfree(vp_dev->msix_entries);
+error_entries:
+	return err;
 }
 
 /* the config->find_vq() implementation */
@@ -242,6 +345,10 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
 	u16 num;
 	int err;
 
+	/* If using IRQ vector per vq, make sure we have enough vectors */
+	if (vp_dev->msix_per_vq_vectors && vp_dev->msix_per_vq_vectors <= index)
+		return ERR_PTR(-ENOENT);
+
 	/* Select the queue we're interested in */
 	iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
 
@@ -285,8 +392,19 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
 	list_add(&info->node, &vp_dev->virtqueues);
 	spin_unlock_irqrestore(&vp_dev->lock, flags);
 
+	/* allocate per-vq irq if neccessary */
+	if (vp_dev->msix_per_vq_vectors) {
+		err = request_irq(vp_dev->msix_entries[vq_vector(index)].vector,
+				  vring_interrupt, 0,
+				  vp_dev->msix_names[vq_vector(index)], vq);
+		if (err)
+			goto out_request_irq;
+	}
+
 	return vq;
 
+out_request_irq:
+	vring_del_virtqueue(vq);
 out_activate_queue:
 	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 	free_pages_exact(info->queue, size);
@@ -302,6 +420,11 @@ static void vp_del_vq(struct virtqueue *vq)
 	struct virtio_pci_vq_info *info = vq->priv;
 	unsigned long flags, size;
 
+	if (vp_dev->msix_per_vq_vectors) {
+		int vector = vq_vector(info->queue_index);
+		free_irq(vp_dev->msix_entries[vector].vector, vq);
+	}
+
 	spin_lock_irqsave(&vp_dev->lock, flags);
 	list_del(&info->node);
 	spin_unlock_irqrestore(&vp_dev->lock, flags);
@@ -323,6 +446,8 @@ static struct virtio_config_ops virtio_pci_config_ops = {
 	.get_status	= vp_get_status,
 	.set_status	= vp_set_status,
 	.reset		= vp_reset,
+	.request_vqs	= vp_request_vqs,
+	.free_vqs	= vp_free_vqs,
 	.find_vq	= vp_find_vq,
 	.del_vq		= vp_del_vq,
 	.get_features	= vp_get_features,
@@ -394,21 +519,13 @@ static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,
 	vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
 	vp_dev->vdev.id.device = pci_dev->subsystem_device;
 
-	/* register a handler for the queue with the PCI device's interrupt */
-	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
-			  dev_name(&vp_dev->vdev.dev), vp_dev);
-	if (err)
-		goto out_set_drvdata;
-
 	/* finally register the virtio device */
 	err = register_virtio_device(&vp_dev->vdev);
 	if (err)
-		goto out_req_irq;
+		goto out_set_drvdata;
 
 	return 0;
 
-out_req_irq:
-	free_irq(pci_dev->irq, vp_dev);
 out_set_drvdata:
 	pci_set_drvdata(pci_dev, NULL);
 	pci_iounmap(pci_dev, vp_dev->ioaddr);
-- 
1.6.0.6

[PATCH 8/8] virtio_pci: optional MSI-X support

[Michael S. Tsirkin]

This implements optional MSI-X support in virtio_pci.
MSI-X is used whenever the host supports at least 2 MSI-X
vectors: 1 for configuration changes and 1 for virtqueues.
Per-virtqueue vectors are allocated if enough vectors
available.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_pci.c |  147 ++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 132 insertions(+), 15 deletions(-)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 151538c..20bdc8c 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -42,8 +42,33 @@ struct virtio_pci_device
 	/* a list of queues so we can dispatch IRQs */
 	spinlock_t lock;
 	struct list_head virtqueues;
+
+	/* MSI-X support */
+	struct msix_entry *msix_entries;
+	/* Name strings for interrupts. This size should be enough,
+	 * and I'm too lazy to allocate each name separately. */
+	char (*msix_names)[256];
+	/* Number of vectors configured at startup (excludes per-virtqueue
+	 * vectors if any) */
+	unsigned msix_preset_vectors;
+	/* Number of per-virtqueue vectors if any. */
+	unsigned msix_per_vq_vectors;
+};
+
+/* Constants for MSI-X */
+/* Use first vector for configuration changes, second and the rest for
+ * virtqueues Thus, we need at least 2 vectors for MSI. */
+enum {
+	VP_MSIX_CONFIG_VECTOR = 0,
+	VP_MSIX_VQ_VECTOR = 1,
+	VP_MSIX_MIN_VECTORS = 2
 };
 
+static inline int vq_vector(int index)
+{
+	return index + VP_MSIX_VQ_VECTOR;
+}
+
 struct virtio_pci_vq_info
 {
 	/* the actual virtqueue */
@@ -221,14 +246,92 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
 	return vp_vring_interrupt(irq, opaque);
 }
 
-	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;
+/* the config->free_vqs() implementation */
+static void vp_free_vqs(struct virtio_device *vdev) {
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	int i;
+
+	for (i = 0; i < vp_dev->msix_preset_vectors; ++i)
+		free_irq(vp_dev->msix_entries[i].vector, vp_dev);
+
+	if (!vp_dev->msix_preset_vectors)
+		free_irq(vp_dev->pci_dev->irq, vp_dev);
+}
+
+/* the config->request_vqs() implementation */
+static int vp_request_vqs(struct virtio_device *vdev, unsigned max_vqs) {
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	const char *name = dev_name(&vp_dev->vdev.dev);
+	unsigned i, vectors;
+	int err = -ENOMEM;
+
+	/* We need at most one vector per queue and one for config changes */
+	vectors = vq_vector(max_vqs);
+	vp_dev->msix_entries = kmalloc(vectors * sizeof *vp_dev->msix_entries,
+				       GFP_KERNEL);
+	if (!vp_dev->msix_entries)
+		goto error_entries;
+	vp_dev->msix_names = kmalloc(vectors * sizeof *vp_dev->msix_names,
+				     GFP_KERNEL);
+	if (!vp_dev->msix_names)
+		goto error_names;
+
+	snprintf(vp_dev->msix_names[VP_MSIX_CONFIG_VECTOR],
+		 sizeof *vp_dev->msix_names, "%s-config", name);
+	for (i = 0; i < max_vqs; ++i)
+		snprintf(vp_dev->msix_names[vq_vector(i)],
+			 sizeof *vp_dev->msix_names, "%s-vq-%d", name, i);
+
+	vp_dev->msix_preset_vectors = 1;
+	vp_dev->msix_per_vq_vectors = max_vqs;
+	for (;;) {
+		err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries,
+				      vectors);
+		/* Error out if not enough vectors */
+		if (err > 0 && err < VP_MSIX_MIN_VECTORS)
+			err = -EBUSY;
+		if (err <= 0)
+			break;
+		/* Not enough vectors for all queues. Retry, disabling
+		 * per-queue interrupts */
+		vectors = VP_MSIX_MIN_VECTORS;
+		vp_dev->msix_preset_vectors = VP_MSIX_MIN_VECTORS;
+		vp_dev->msix_per_vq_vectors = 0;
+		snprintf(vp_dev->msix_names[VP_MSIX_VQ_VECTOR],
+			 sizeof *vp_dev->msix_names, "%s-vq", name);
 	}
-	spin_unlock_irqrestore(&vp_dev->lock, flags);
 
-	return ret;
+	if (err) {
+		/* Can't allocate enough MSI-X vectors, use regular interrupt */
+		vp_dev->msix_preset_vectors = 0;
+		vp_dev->msix_per_vq_vectors = 0;
+		/* Register a handler for the queue with the PCI device's
+		 * interrupt */
+		err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
+				  IRQF_SHARED, name, vp_dev);
+		if (err)
+			goto error_irq;
+	}
+	for (i = 0; i < vp_dev->msix_preset_vectors; ++i) {
+		err = request_irq(vp_dev->msix_entries[i].vector,
+				  i == VP_MSIX_CONFIG_VECTOR ?
+				  vp_config_changed : vp_vring_interrupt,
+				  0, vp_dev->msix_names[i], vp_dev);
+		if (err) {
+			/* Set msix_preset_vectors so that only vectors we
+			 * already allocated will be freed by vp_free_vqs. */
+			vp_dev->msix_preset_vectors = i;
+			goto error_irq;
+		}
+	}
+	return 0;
+error_irq:
+	vp_free_vqs(vdev);
+	kfree(vp_dev->msix_names);
+error_names:
+	kfree(vp_dev->msix_entries);
+error_entries:
+	return err;
 }
 
 /* the config->find_vq() implementation */
@@ -242,6 +345,10 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
 	u16 num;
 	int err;
 
+	/* If using IRQ vector per vq, make sure we have enough vectors */
+	if (vp_dev->msix_per_vq_vectors && vp_dev->msix_per_vq_vectors <= index)
+		return ERR_PTR(-ENOENT);
+
 	/* Select the queue we're interested in */
 	iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
 
@@ -285,8 +392,19 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
 	list_add(&info->node, &vp_dev->virtqueues);
 	spin_unlock_irqrestore(&vp_dev->lock, flags);
 
+	/* allocate per-vq irq if neccessary */
+	if (vp_dev->msix_per_vq_vectors) {
+		err = request_irq(vp_dev->msix_entries[vq_vector(index)].vector,
+				  vring_interrupt, 0,
+				  vp_dev->msix_names[vq_vector(index)], vq);
+		if (err)
+			goto out_request_irq;
+	}
+
 	return vq;
 
+out_request_irq:
+	vring_del_virtqueue(vq);
 out_activate_queue:
 	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 	free_pages_exact(info->queue, size);
@@ -302,6 +420,11 @@ static void vp_del_vq(struct virtqueue *vq)
 	struct virtio_pci_vq_info *info = vq->priv;
 	unsigned long flags, size;
 
+	if (vp_dev->msix_per_vq_vectors) {
+		int vector = vq_vector(info->queue_index);
+		free_irq(vp_dev->msix_entries[vector].vector, vq);
+	}
+
 	spin_lock_irqsave(&vp_dev->lock, flags);
 	list_del(&info->node);
 	spin_unlock_irqrestore(&vp_dev->lock, flags);
@@ -323,6 +446,8 @@ static struct virtio_config_ops virtio_pci_config_ops = {
 	.get_status	= vp_get_status,
 	.set_status	= vp_set_status,
 	.reset		= vp_reset,
+	.request_vqs	= vp_request_vqs,
+	.free_vqs	= vp_free_vqs,
 	.find_vq	= vp_find_vq,
 	.del_vq		= vp_del_vq,
 	.get_features	= vp_get_features,
@@ -394,21 +519,13 @@ static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,
 	vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
 	vp_dev->vdev.id.device = pci_dev->subsystem_device;
 
-	/* register a handler for the queue with the PCI device's interrupt */
-	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
-			  dev_name(&vp_dev->vdev.dev), vp_dev);
-	if (err)
-		goto out_set_drvdata;
-
 	/* finally register the virtio device */
 	err = register_virtio_device(&vp_dev->vdev);
 	if (err)
-		goto out_req_irq;
+		goto out_set_drvdata;
 
 	return 0;
 
-out_req_irq:
-	free_irq(pci_dev->irq, vp_dev);
 out_set_drvdata:
 	pci_set_drvdata(pci_dev, NULL);
 	pci_iounmap(pci_dev, vp_dev->ioaddr);
-- 
1.6.0.6