Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull virtio updates from Michael Tsirkin:
 "Fixes, cleanups, performance

  A bunch of changes to virtio, most affecting virtio net. Also ptr_ring
  batched zeroing - first of batching enhancements that seems ready."

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  s390/virtio: change maintainership
  tools/virtio: fix spelling mistake: "wakeus" -> "wakeups"
  virtio_net: tidy a couple debug statements
  ptr_ring: support testing different batching sizes
  ringtest: support test specific parameters
  ptr_ring: batch ring zeroing
  virtio: virtio_driver doc
  virtio_net: don't reset twice on XDP on/off
  virtio_net: fix support for small rings
  virtio_net: reduce alignment for buffers
  virtio_net: rework mergeable buffer handling
  virtio_net: allow specifying context for rx
  virtio: allow extra context per descriptor
  tools/virtio: fix build breakage
  virtio: add context flag to find vqs
  virtio: wrap find_vqs
  ringtest: fix an assert statement

1 files changed, 83 insertions, 64 deletions

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 1c6d3923c224..9320d96a1632 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -29,6 +29,7 @@
 #include <linux/slab.h>
 #include <linux/cpu.h>
 #include <linux/average.h>
+#include <net/route.h>
 
 static int napi_weight = NAPI_POLL_WEIGHT;
 module_param(napi_weight, int, 0444);
@@ -54,17 +55,6 @@ module_param(napi_tx, bool, 0644);
  */
 DECLARE_EWMA(pkt_len, 0, 64)
 
-/* With mergeable buffers we align buffer address and use the low bits to
- * encode its true size. Buffer size is up to 1 page so we need to align to
- * square root of page size to ensure we reserve enough bits to encode the true
- * size.
- */
-#define MERGEABLE_BUFFER_MIN_ALIGN_SHIFT ((PAGE_SHIFT + 1) / 2)
-
-/* Minimum alignment for mergeable packet buffers. */
-#define MERGEABLE_BUFFER_ALIGN max(L1_CACHE_BYTES, \
-				   1 << MERGEABLE_BUFFER_MIN_ALIGN_SHIFT)
-
 #define VIRTNET_DRIVER_VERSION "1.0.0"
 
 struct virtnet_stats {
@@ -112,6 +102,9 @@ struct receive_queue {
 	/* RX: fragments + linear part + virtio header */
 	struct scatterlist sg[MAX_SKB_FRAGS + 2];
 
+	/* Min single buffer size for mergeable buffers case. */
+	unsigned int min_buf_len;
+
 	/* Name of this receive queue: input.$index */
 	char name[40];
 };
@@ -277,24 +270,6 @@ static void skb_xmit_done(struct virtqueue *vq)
 		netif_wake_subqueue(vi->dev, vq2txq(vq));
 }
 
-static unsigned int mergeable_ctx_to_buf_truesize(unsigned long mrg_ctx)
-{
-	unsigned int truesize = mrg_ctx & (MERGEABLE_BUFFER_ALIGN - 1);
-	return (truesize + 1) * MERGEABLE_BUFFER_ALIGN;
-}
-
-static void *mergeable_ctx_to_buf_address(unsigned long mrg_ctx)
-{
-	return (void *)(mrg_ctx & -MERGEABLE_BUFFER_ALIGN);
-
-}
-
-static unsigned long mergeable_buf_to_ctx(void *buf, unsigned int truesize)
-{
-	unsigned int size = truesize / MERGEABLE_BUFFER_ALIGN;
-	return (unsigned long)buf | (size - 1);
-}
-
 /* Called from bottom half context */
 static struct sk_buff *page_to_skb(struct virtnet_info *vi,
 				   struct receive_queue *rq,
@@ -538,15 +513,13 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
 
 	while (--*num_buf) {
 		unsigned int buflen;
-		unsigned long ctx;
 		void *buf;
 		int off;
 
-		ctx = (unsigned long)virtqueue_get_buf(rq->vq, &buflen);
-		if (unlikely(!ctx))
+		buf = virtqueue_get_buf(rq->vq, &buflen);
+		if (unlikely(!buf))
 			goto err_buf;
 
-		buf = mergeable_ctx_to_buf_address(ctx);
 		p = virt_to_head_page(buf);
 		off = buf - page_address(p);
 
@@ -575,10 +548,10 @@ err_buf:
 static struct sk_buff *receive_mergeable(struct net_device *dev,
 					 struct virtnet_info *vi,
 					 struct receive_queue *rq,
-					 unsigned long ctx,
+					 void *buf,
+					 void *ctx,
 					 unsigned int len)
 {
-	void *buf = mergeable_ctx_to_buf_address(ctx);
 	struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
 	u16 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
 	struct page *page = virt_to_head_page(buf);
@@ -666,7 +639,13 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	}
 	rcu_read_unlock();
 
-	truesize = max(len, mergeable_ctx_to_buf_truesize(ctx));
+	if (unlikely(len > (unsigned long)ctx)) {
+		pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
+			 dev->name, len, (unsigned long)ctx);
+		dev->stats.rx_length_errors++;
+		goto err_skb;
+	}
+	truesize = (unsigned long)ctx;
 	head_skb = page_to_skb(vi, rq, page, offset, len, truesize);
 	curr_skb = head_skb;
 
@@ -675,7 +654,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	while (--num_buf) {
 		int num_skb_frags;
 
-		ctx = (unsigned long)virtqueue_get_buf(rq->vq, &len);
+		buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
 		if (unlikely(!ctx)) {
 			pr_debug("%s: rx error: %d buffers out of %d missing\n",
 				 dev->name, num_buf,
@@ -685,8 +664,14 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 			goto err_buf;
 		}
 
-		buf = mergeable_ctx_to_buf_address(ctx);
 		page = virt_to_head_page(buf);
+		if (unlikely(len > (unsigned long)ctx)) {
+			pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
+				 dev->name, len, (unsigned long)ctx);
+			dev->stats.rx_length_errors++;
+			goto err_skb;
+		}
+		truesize = (unsigned long)ctx;
 
 		num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
 		if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
@@ -702,7 +687,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 			head_skb->truesize += nskb->truesize;
 			num_skb_frags = 0;
 		}
-		truesize = max(len, mergeable_ctx_to_buf_truesize(ctx));
 		if (curr_skb != head_skb) {
 			head_skb->data_len += len;
 			head_skb->len += len;
@@ -727,14 +711,14 @@ err_xdp:
 err_skb:
 	put_page(page);
 	while (--num_buf) {
-		ctx = (unsigned long)virtqueue_get_buf(rq->vq, &len);
-		if (unlikely(!ctx)) {
+		buf = virtqueue_get_buf(rq->vq, &len);
+		if (unlikely(!buf)) {
 			pr_debug("%s: rx error: %d buffers missing\n",
 				 dev->name, num_buf);
 			dev->stats.rx_length_errors++;
 			break;
 		}
-		page = virt_to_head_page(mergeable_ctx_to_buf_address(ctx));
+		page = virt_to_head_page(buf);
 		put_page(page);
 	}
 err_buf:
@@ -745,7 +729,7 @@ xdp_xmit:
 }
 
 static int receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
-		       void *buf, unsigned int len)
+		       void *buf, unsigned int len, void **ctx)
 {
 	struct net_device *dev = vi->dev;
 	struct sk_buff *skb;
@@ -756,9 +740,7 @@ static int receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 		pr_debug("%s: short packet %i\n", dev->name, len);
 		dev->stats.rx_length_errors++;
 		if (vi->mergeable_rx_bufs) {
-			unsigned long ctx = (unsigned long)buf;
-			void *base = mergeable_ctx_to_buf_address(ctx);
-			put_page(virt_to_head_page(base));
+			put_page(virt_to_head_page(buf));
 		} else if (vi->big_packets) {
 			give_pages(rq, buf);
 		} else {
@@ -768,7 +750,7 @@ static int receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 	}
 
 	if (vi->mergeable_rx_bufs)
-		skb = receive_mergeable(dev, vi, rq, (unsigned long)buf, len);
+		skb = receive_mergeable(dev, vi, rq, buf, ctx, len);
 	else if (vi->big_packets)
 		skb = receive_big(dev, vi, rq, buf, len);
 	else
@@ -880,14 +862,15 @@ static int add_recvbuf_big(struct virtnet_info *vi, struct receive_queue *rq,
 	return err;
 }
 
-static unsigned int get_mergeable_buf_len(struct ewma_pkt_len *avg_pkt_len)
+static unsigned int get_mergeable_buf_len(struct receive_queue *rq,
+					  struct ewma_pkt_len *avg_pkt_len)
 {
 	const size_t hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
 	unsigned int len;
 
 	len = hdr_len + clamp_t(unsigned int, ewma_pkt_len_read(avg_pkt_len),
-			GOOD_PACKET_LEN, PAGE_SIZE - hdr_len);
-	return ALIGN(len, MERGEABLE_BUFFER_ALIGN);
+				rq->min_buf_len - hdr_len, PAGE_SIZE - hdr_len);
+	return ALIGN(len, L1_CACHE_BYTES);
 }
 
 static int add_recvbuf_mergeable(struct virtnet_info *vi,
@@ -896,17 +879,17 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
 	struct page_frag *alloc_frag = &rq->alloc_frag;
 	unsigned int headroom = virtnet_get_headroom(vi);
 	char *buf;
-	unsigned long ctx;
+	void *ctx;
 	int err;
 	unsigned int len, hole;
 
-	len = get_mergeable_buf_len(&rq->mrg_avg_pkt_len);
+	len = get_mergeable_buf_len(rq, &rq->mrg_avg_pkt_len);
 	if (unlikely(!skb_page_frag_refill(len + headroom, alloc_frag, gfp)))
 		return -ENOMEM;
 
 	buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
 	buf += headroom; /* advance address leaving hole at front of pkt */
-	ctx = mergeable_buf_to_ctx(buf, len);
+	ctx = (void *)(unsigned long)len;
 	get_page(alloc_frag->page);
 	alloc_frag->offset += len + headroom;
 	hole = alloc_frag->size - alloc_frag->offset;
@@ -921,7 +904,7 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
 	}
 
 	sg_init_one(rq->sg, buf, len);
-	err = virtqueue_add_inbuf(rq->vq, rq->sg, 1, (void *)ctx, gfp);
+	err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
 	if (err < 0)
 		put_page(virt_to_head_page(buf));
 
@@ -1032,10 +1015,20 @@ static int virtnet_receive(struct receive_queue *rq, int budget)
 	void *buf;
 	struct virtnet_stats *stats = this_cpu_ptr(vi->stats);
 
-	while (received < budget &&
-	       (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
-		bytes += receive_buf(vi, rq, buf, len);
-		received++;
+	if (vi->mergeable_rx_bufs) {
+		void *ctx;
+
+		while (received < budget &&
+		       (buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx))) {
+			bytes += receive_buf(vi, rq, buf, len, ctx);
+			received++;
+		}
+	} else {
+		while (received < budget &&
+		       (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
+			bytes += receive_buf(vi, rq, buf, len, NULL);
+			received++;
+		}
 	}
 
 	if (rq->vq->num_free > virtqueue_get_vring_size(rq->vq) / 2) {
@@ -1854,7 +1847,6 @@ static int virtnet_reset(struct virtnet_info *vi, int curr_qp, int xdp_qp)
 	virtnet_freeze_down(dev);
 	_remove_vq_common(vi);
 
-	dev->config->reset(dev);
 	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 
@@ -2118,9 +2110,7 @@ static void free_unused_bufs(struct virtnet_info *vi)
 
 		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) {
 			if (vi->mergeable_rx_bufs) {
-				unsigned long ctx = (unsigned long)buf;
-				void *base = mergeable_ctx_to_buf_address(ctx);
-				put_page(virt_to_head_page(base));
+				put_page(virt_to_head_page(buf));
 			} else if (vi->big_packets) {
 				give_pages(&vi->rq[i], buf);
 			} else {
@@ -2141,6 +2131,21 @@ static void virtnet_del_vqs(struct virtnet_info *vi)
 	virtnet_free_queues(vi);
 }
 
+/* How large should a single buffer be so a queue full of these can fit at
+ * least one full packet?
+ * Logic below assumes the mergeable buffer header is used.
+ */
+static unsigned int mergeable_min_buf_len(struct virtnet_info *vi, struct virtqueue *vq)
+{
+	const unsigned int hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
+	unsigned int rq_size = virtqueue_get_vring_size(vq);
+	unsigned int packet_len = vi->big_packets ? IP_MAX_MTU : vi->dev->max_mtu;
+	unsigned int buf_len = hdr_len + ETH_HLEN + VLAN_HLEN + packet_len;
+	unsigned int min_buf_len = DIV_ROUND_UP(buf_len, rq_size);
+
+	return max(min_buf_len, hdr_len);
+}
+
 static int virtnet_find_vqs(struct virtnet_info *vi)
 {
 	vq_callback_t **callbacks;
@@ -2148,6 +2153,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 	int ret = -ENOMEM;
 	int i, total_vqs;
 	const char **names;
+	bool *ctx;
 
 	/* We expect 1 RX virtqueue followed by 1 TX virtqueue, followed by
 	 * possible N-1 RX/TX queue pairs used in multiqueue mode, followed by
@@ -2166,6 +2172,13 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 	names = kmalloc(total_vqs * sizeof(*names), GFP_KERNEL);
 	if (!names)
 		goto err_names;
+	if (vi->mergeable_rx_bufs) {
+		ctx = kzalloc(total_vqs * sizeof(*ctx), GFP_KERNEL);
+		if (!ctx)
+			goto err_ctx;
+	} else {
+		ctx = NULL;
+	}
 
 	/* Parameters for control virtqueue, if any */
 	if (vi->has_cvq) {
@@ -2181,10 +2194,12 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 		sprintf(vi->sq[i].name, "output.%d", i);
 		names[rxq2vq(i)] = vi->rq[i].name;
 		names[txq2vq(i)] = vi->sq[i].name;
+		if (ctx)
+			ctx[rxq2vq(i)] = true;
 	}
 
 	ret = vi->vdev->config->find_vqs(vi->vdev, total_vqs, vqs, callbacks,
-					 names, NULL);
+					 names, ctx, NULL);
 	if (ret)
 		goto err_find;
 
@@ -2196,6 +2211,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 
 	for (i = 0; i < vi->max_queue_pairs; i++) {
 		vi->rq[i].vq = vqs[rxq2vq(i)];
+		vi->rq[i].min_buf_len = mergeable_min_buf_len(vi, vi->rq[i].vq);
 		vi->sq[i].vq = vqs[txq2vq(i)];
 	}
 
@@ -2206,6 +2222,8 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 	return 0;
 
 err_find:
+	kfree(ctx);
+err_ctx:
 	kfree(names);
 err_names:
 	kfree(callbacks);
@@ -2282,7 +2300,8 @@ static ssize_t mergeable_rx_buffer_size_show(struct netdev_rx_queue *queue,
 
 	BUG_ON(queue_index >= vi->max_queue_pairs);
 	avg = &vi->rq[queue_index].mrg_avg_pkt_len;
-	return sprintf(buf, "%u\n", get_mergeable_buf_len(avg));
+	return sprintf(buf, "%u\n",
+		       get_mergeable_buf_len(&vi->rq[queue_index], avg));
 }
 
 static struct rx_queue_attribute mergeable_rx_buffer_size_attribute =