Nothing exciting: virtio-blk users might see a bit of a boost from the

doubling of the default queue length though.
 
 Cheers,
 Rusty.
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Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull virtio updates from Rusty Russell:
 "Nothing exciting: virtio-blk users might see a bit of a boost from the
  doubling of the default queue length though"

* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  virtio-blk: base queue-depth on virtqueue ringsize or module param
  Revert a02bbb1ccf: MAINTAINERS: add virtio-dev ML for virtio
  virtio: fail adding buffer on broken queues.
  virtio-rng: don't crash if virtqueue is broken.
  virtio_balloon: don't crash if virtqueue is broken.
  virtio_blk: don't crash, report error if virtqueue is broken.
  virtio_net: don't crash if virtqueue is broken.
  virtio_balloon: don't softlockup on huge balloon changes.
  virtio: Use pci_enable_msix_exact() instead of pci_enable_msix()
  MAINTAINERS: virtio-dev is subscribers only
  tools/virtio: add a missing )
  tools/virtio: fix missing kmemleak_ignore symbol
  tools/virtio: update internal copies of headers

MAINTAINERS

@@ -9432,7 +9432,6 @@ F:	include/media/videobuf2-*
 
 VIRTIO CONSOLE DRIVER
 M:	Amit Shah <amit.shah@redhat.com>
-L:	virtio-dev@lists.oasis-open.org
 L:	virtualization@lists.linux-foundation.org
 S:	Maintained
 F:	drivers/char/virtio_console.c
@@ -9442,7 +9441,6 @@ F:	include/uapi/linux/virtio_console.h
 VIRTIO CORE, NET AND BLOCK DRIVERS
 M:	Rusty Russell <rusty@rustcorp.com.au>
 M:	"Michael S. Tsirkin" <mst@redhat.com>
-L:	virtio-dev@lists.oasis-open.org
 L:	virtualization@lists.linux-foundation.org
 S:	Maintained
 F:	drivers/virtio/
@@ -9455,7 +9453,6 @@ F:	include/uapi/linux/virtio_*.h
 VIRTIO HOST (VHOST)
 M:	"Michael S. Tsirkin" <mst@redhat.com>
 L:	kvm@vger.kernel.org
-L:	virtio-dev@lists.oasis-open.org
 L:	virtualization@lists.linux-foundation.org
 L:	netdev@vger.kernel.org
 S:	Maintained

drivers/block/virtio_blk.c

@@ -158,6 +158,7 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
 	unsigned long flags;
 	unsigned int num;
 	const bool last = (req->cmd_flags & REQ_END) != 0;
+	int err;
 
 	BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
 
@@ -198,11 +199,16 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
 	}
 
 	spin_lock_irqsave(&vblk->vq_lock, flags);
-	if (__virtblk_add_req(vblk->vq, vbr, vbr->sg, num) < 0) {
+	err = __virtblk_add_req(vblk->vq, vbr, vbr->sg, num);
+	if (err) {
 		virtqueue_kick(vblk->vq);
 		spin_unlock_irqrestore(&vblk->vq_lock, flags);
 		blk_mq_stop_hw_queue(hctx);
+		/* Out of mem doesn't actually happen, since we fall back
+		 * to direct descriptors */
+		if (err == -ENOMEM || err == -ENOSPC)
 			return BLK_MQ_RQ_QUEUE_BUSY;
+		return BLK_MQ_RQ_QUEUE_ERROR;
 	}
 
 	if (last)
@@ -485,10 +491,11 @@ static struct blk_mq_ops virtio_mq_ops = {
 static struct blk_mq_reg virtio_mq_reg = {
 	.ops		= &virtio_mq_ops,
 	.nr_hw_queues	= 1,
-	.queue_depth	= 64,
+	.queue_depth	= 0, /* Set in virtblk_probe */
 	.numa_node	= NUMA_NO_NODE,
 	.flags		= BLK_MQ_F_SHOULD_MERGE,
 };
+module_param_named(queue_depth, virtio_mq_reg.queue_depth, uint, 0444);
 
 static int virtblk_init_vbr(void *data, struct blk_mq_hw_ctx *hctx,
 			     struct request *rq, unsigned int nr)
@@ -553,6 +560,13 @@ static int virtblk_probe(struct virtio_device *vdev)
 		goto out_free_vq;
 	}
 
+	/* Default queue sizing is to fill the ring. */
+	if (!virtio_mq_reg.queue_depth) {
+		virtio_mq_reg.queue_depth = vblk->vq->num_free;
+		/* ... but without indirect descs, we use 2 descs per req */
+		if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
+			virtio_mq_reg.queue_depth /= 2;
+	}
 	virtio_mq_reg.cmd_size =
 		sizeof(struct virtblk_req) +
 		sizeof(struct scatterlist) * sg_elems;

drivers/char/hw_random/virtio-rng.c

@@ -47,8 +47,7 @@ static void register_buffer(u8 *buf, size_t size)
 	sg_init_one(&sg, buf, size);
 
 	/* There should always be room for one buffer. */
-	if (virtqueue_add_inbuf(vq, &sg, 1, buf, GFP_KERNEL) < 0)
+	virtqueue_add_inbuf(vq, &sg, 1, buf, GFP_KERNEL);
-		BUG();
 
 	virtqueue_kick(vq);
 }

drivers/net/virtio_net.c

@@ -938,7 +938,7 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
 	sgs[out_num] = &stat;
 
 	BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
-	BUG_ON(virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC) < 0);
+	virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
 
 	if (unlikely(!virtqueue_kick(vi->cvq)))
 		return status == VIRTIO_NET_OK;

drivers/virtio/virtio_balloon.c

@@ -108,8 +108,7 @@ static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
 	sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
 
 	/* We should always be able to add one buffer to an empty queue. */
-	if (virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL) < 0)
+	virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
-		BUG();
 	virtqueue_kick(vq);
 
 	/* When host has read buffer, this completes via balloon_ack */
@@ -258,8 +257,7 @@ static void stats_handle_request(struct virtio_balloon *vb)
 	if (!virtqueue_get_buf(vq, &len))
 		return;
 	sg_init_one(&sg, vb->stats, sizeof(vb->stats));
-	if (virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL) < 0)
+	virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
-		BUG();
 	virtqueue_kick(vq);
 }
 
@@ -310,6 +308,12 @@ static int balloon(void *_vballoon)
 		else if (diff < 0)
 			leak_balloon(vb, -diff);
 		update_balloon_size(vb);
+
+		/*
+		 * For large balloon changes, we could spend a lot of time
+		 * and always have work to do.  Be nice if preempt disabled.
+		 */
+		cond_resched();
 	}
 	return 0;
 }
@@ -338,7 +342,7 @@ static int init_vqs(struct virtio_balloon *vb)
 
 		/*
 		 * Prime this virtqueue with one buffer so the hypervisor can
-		 * use it to signal us later.
+		 * use it to signal us later (it can't be broken yet!).
 		 */
 		sg_init_one(&sg, vb->stats, sizeof vb->stats);
 		if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)

drivers/virtio/virtio_pci.c

@@ -333,10 +333,8 @@ static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
 	for (i = 0; i < nvectors; ++i)
 		vp_dev->msix_entries[i].entry = i;
 
-	/* pci_enable_msix returns positive if we can't get this many. */
+	err = pci_enable_msix_exact(vp_dev->pci_dev,
-	err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries, nvectors);
+				    vp_dev->msix_entries, nvectors);
-	if (err > 0)
-		err = -ENOSPC;
 	if (err)
 		goto error;
 	vp_dev->msix_enabled = 1;

drivers/virtio/virtio_ring.c

@@ -23,6 +23,7 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/hrtimer.h>
+#include <linux/kmemleak.h>
 
 #ifdef DEBUG
 /* For development, we want to crash whenever the ring is screwed. */
@@ -203,6 +204,11 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 
 	BUG_ON(data == NULL);
 
+	if (unlikely(vq->broken)) {
+		END_USE(vq);
+		return -EIO;
+	}
+
 #ifdef DEBUG
 	{
 		ktime_t now = ktime_get();
@@ -309,7 +315,7 @@ add_head:
  * Caller must ensure we don't call this with other virtqueue operations
  * at the same time (except where noted).
  *
- * Returns zero or a negative error (ie. ENOSPC, ENOMEM).
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
  */
 int virtqueue_add_sgs(struct virtqueue *_vq,
 		      struct scatterlist *sgs[],
@@ -347,7 +353,7 @@ EXPORT_SYMBOL_GPL(virtqueue_add_sgs);
  * Caller must ensure we don't call this with other virtqueue operations
  * at the same time (except where noted).
  *
- * Returns zero or a negative error (ie. ENOSPC, ENOMEM).
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
  */
 int virtqueue_add_outbuf(struct virtqueue *vq,
 			 struct scatterlist sg[], unsigned int num,
@@ -369,7 +375,7 @@ EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
  * Caller must ensure we don't call this with other virtqueue operations
  * at the same time (except where noted).
  *
- * Returns zero or a negative error (ie. ENOSPC, ENOMEM).
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
  */
 int virtqueue_add_inbuf(struct virtqueue *vq,
 			struct scatterlist sg[], unsigned int num,

tools/virtio/linux/kmemleak.h

@@ -0,0 +1,3 @@
+static inline void kmemleak_ignore(const void *ptr)
+{
+}

tools/virtio/linux/virtio.h

@@ -63,7 +63,7 @@ int virtqueue_add_inbuf(struct virtqueue *vq,
 			void *data,
 			gfp_t gfp);
 
-void virtqueue_kick(struct virtqueue *vq);
+bool virtqueue_kick(struct virtqueue *vq);
 
 void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
 
@@ -79,7 +79,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
 				      struct virtio_device *vdev,
 				      bool weak_barriers,
 				      void *pages,
-				      void (*notify)(struct virtqueue *vq),
+				      bool (*notify)(struct virtqueue *vq),
 				      void (*callback)(struct virtqueue *vq),
 				      const char *name);
 void vring_del_virtqueue(struct virtqueue *vq);

tools/virtio/virtio_test.c

@@ -172,7 +172,7 @@ static void run_test(struct vdev_info *dev, struct vq_info *vq,
 							 GFP_ATOMIC);
 				if (likely(r == 0)) {
 					++started;
-					if (unlikely(!virtqueue_kick(vq->vq))
+					if (unlikely(!virtqueue_kick(vq->vq)))
 						r = -1;
 				}
 			} else