[dpdk-stable] patch 'net/virtio: fix memory init with vDPA backend' has been queued to stable release 20.11.1

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 20.11.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 02/07/21. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/bluca/dpdk-stable

This queued commit can be viewed at:
https://github.com/bluca/dpdk-stable/commit/093202401799d533d5a1c17108e8028eaae85889

Thanks.

Luca Boccassi

---
>From 093202401799d533d5a1c17108e8028eaae85889 Mon Sep 17 00:00:00 2001
From: Maxime Coquelin <maxime.coquelin at redhat.com>
Date: Fri, 8 Jan 2021 10:41:49 +0100
Subject: [PATCH] net/virtio: fix memory init with vDPA backend

[ upstream commit a121f175722f7b717cb7576c5baff1c20dd3920e ]

This patch fixes an overhead met with mlx5-vdpa Kernel
driver, where for every page in the mapped area, all the
memory tables gets updated. For example, with 2MB hugepages,
a single IOTLB_UPDATE for a 1GB region causes 512 memory
updates on mlx5-vdpa side.

Using batching mode, the mlx5 driver will only trigger a
single memory update for all the IOTLB updates that happen
between the batch begin and batch end commands.

Fixes: 6b901437056e ("net/virtio: introduce vhost-vDPA backend")

Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
Reviewed-by: Chenbo Xia <chenbo.xia at intel.com>
---
 drivers/net/virtio/virtio_user/vhost.h        |   4 +
 drivers/net/virtio/virtio_user/vhost_vdpa.c   | 106 +++++++++++++++++-
 .../net/virtio/virtio_user/virtio_user_dev.c  |   3 +-
 3 files changed, 107 insertions(+), 6 deletions(-)

diff --git a/drivers/net/virtio/virtio_user/vhost.h b/drivers/net/virtio/virtio_user/vhost.h
index c1dcc50b58..be286173b0 100644
--- a/drivers/net/virtio/virtio_user/vhost.h
+++ b/drivers/net/virtio/virtio_user/vhost.h
@@ -90,6 +90,10 @@ enum vhost_user_request {
 #define VHOST_BACKEND_F_IOTLB_MSG_V2 1
 #endif
 
+#ifndef VHOST_BACKEND_F_IOTLB_BATCH
+#define VHOST_BACKEND_F_IOTLB_BATCH 2
+#endif
+
 extern const char * const vhost_msg_strings[VHOST_USER_MAX];
 
 struct vhost_memory_region {
diff --git a/drivers/net/virtio/virtio_user/vhost_vdpa.c b/drivers/net/virtio/virtio_user/vhost_vdpa.c
index b6c81d6f17..269bab2f8e 100644
--- a/drivers/net/virtio/virtio_user/vhost_vdpa.c
+++ b/drivers/net/virtio/virtio_user/vhost_vdpa.c
@@ -70,6 +70,8 @@ struct vhost_iotlb_msg {
 #define VHOST_IOTLB_UPDATE         2
 #define VHOST_IOTLB_INVALIDATE     3
 #define VHOST_IOTLB_ACCESS_FAIL    4
+#define VHOST_IOTLB_BATCH_BEGIN    5
+#define VHOST_IOTLB_BATCH_END      6
 	uint8_t type;
 };
 
@@ -84,6 +86,56 @@ struct vhost_msg {
 	};
 };
 
+static int
+vhost_vdpa_iotlb_batch_begin(struct virtio_user_dev *dev)
+{
+	struct vhost_msg msg = {};
+
+	if (!(dev->protocol_features & (1ULL << VHOST_BACKEND_F_IOTLB_BATCH)))
+		return 0;
+
+	if (!(dev->protocol_features & (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2))) {
+		PMD_DRV_LOG(ERR, "IOTLB_MSG_V2 not supported by the backend.");
+		return -1;
+	}
+
+	msg.type = VHOST_IOTLB_MSG_V2;
+	msg.iotlb.type = VHOST_IOTLB_BATCH_BEGIN;
+
+	if (write(dev->vhostfd, &msg, sizeof(msg)) != sizeof(msg)) {
+		PMD_DRV_LOG(ERR, "Failed to send IOTLB batch begin (%s)",
+				strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+static int
+vhost_vdpa_iotlb_batch_end(struct virtio_user_dev *dev)
+{
+	struct vhost_msg msg = {};
+
+	if (!(dev->protocol_features & (1ULL << VHOST_BACKEND_F_IOTLB_BATCH)))
+		return 0;
+
+	if (!(dev->protocol_features & (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2))) {
+		PMD_DRV_LOG(ERR, "IOTLB_MSG_V2 not supported by the backend.");
+		return -1;
+	}
+
+	msg.type = VHOST_IOTLB_MSG_V2;
+	msg.iotlb.type = VHOST_IOTLB_BATCH_END;
+
+	if (write(dev->vhostfd, &msg, sizeof(msg)) != sizeof(msg)) {
+		PMD_DRV_LOG(ERR, "Failed to send IOTLB batch end (%s)",
+				strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
 static int
 vhost_vdpa_dma_map(struct virtio_user_dev *dev, void *addr,
 				  uint64_t iova, size_t len)
@@ -136,6 +188,39 @@ vhost_vdpa_dma_unmap(struct virtio_user_dev *dev, __rte_unused void *addr,
 	return 0;
 }
 
+static int
+vhost_vdpa_dma_map_batch(struct virtio_user_dev *dev, void *addr,
+				  uint64_t iova, size_t len)
+{
+	int ret;
+
+	if (vhost_vdpa_iotlb_batch_begin(dev) < 0)
+		return -1;
+
+	ret = vhost_vdpa_dma_map(dev, addr, iova, len);
+
+	if (vhost_vdpa_iotlb_batch_end(dev) < 0)
+		return -1;
+
+	return ret;
+}
+
+static int
+vhost_vdpa_dma_unmap_batch(struct virtio_user_dev *dev, void *addr,
+				  uint64_t iova, size_t len)
+{
+	int ret;
+
+	if (vhost_vdpa_iotlb_batch_begin(dev) < 0)
+		return -1;
+
+	ret = vhost_vdpa_dma_unmap(dev, addr, iova, len);
+
+	if (vhost_vdpa_iotlb_batch_end(dev) < 0)
+		return -1;
+
+	return ret;
+}
 
 static int
 vhost_vdpa_map_contig(const struct rte_memseg_list *msl,
@@ -173,21 +258,32 @@ vhost_vdpa_map(const struct rte_memseg_list *msl, const struct rte_memseg *ms,
 static int
 vhost_vdpa_dma_map_all(struct virtio_user_dev *dev)
 {
+	int ret;
+
+	if (vhost_vdpa_iotlb_batch_begin(dev) < 0)
+		return -1;
+
 	vhost_vdpa_dma_unmap(dev, NULL, 0, SIZE_MAX);
 
 	if (rte_eal_iova_mode() == RTE_IOVA_VA) {
 		/* with IOVA as VA mode, we can get away with mapping contiguous
 		 * chunks rather than going page-by-page.
 		 */
-		int ret = rte_memseg_contig_walk_thread_unsafe(
+		ret = rte_memseg_contig_walk_thread_unsafe(
 				vhost_vdpa_map_contig, dev);
 		if (ret)
-			return ret;
+			goto batch_end;
 		/* we have to continue the walk because we've skipped the
 		 * external segments during the config walk.
 		 */
 	}
-	return rte_memseg_walk_thread_unsafe(vhost_vdpa_map, dev);
+	ret = rte_memseg_walk_thread_unsafe(vhost_vdpa_map, dev);
+
+batch_end:
+	if (vhost_vdpa_iotlb_batch_end(dev) < 0)
+		return -1;
+
+	return ret;
 }
 
 /* with below features, vhost vdpa does not need to do the checksum and TSO,
@@ -307,6 +403,6 @@ struct virtio_user_backend_ops virtio_ops_vdpa = {
 	.setup = vhost_vdpa_setup,
 	.send_request = vhost_vdpa_ioctl,
 	.enable_qp = vhost_vdpa_enable_queue_pair,
-	.dma_map = vhost_vdpa_dma_map,
-	.dma_unmap = vhost_vdpa_dma_unmap,
+	.dma_map = vhost_vdpa_dma_map_batch,
+	.dma_unmap = vhost_vdpa_dma_unmap_batch,
 };
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
index 39c5dfc9e4..202431ca22 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
@@ -446,7 +446,8 @@ virtio_user_dev_setup(struct virtio_user_dev *dev)
 	 1ULL << VHOST_USER_PROTOCOL_F_STATUS)
 
 #define VHOST_VDPA_SUPPORTED_PROTOCOL_FEATURES		\
-	(1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
+	(1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2	|	\
+	1ULL << VHOST_BACKEND_F_IOTLB_BATCH)
 int
 virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
 		     int cq, int queue_size, const char *mac, char **ifname,
-- 
2.29.2

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2021-02-05 11:18:33.745396908 +0000
+++ 0100-net-virtio-fix-memory-init-with-vDPA-backend.patch	2021-02-05 11:18:28.950693853 +0000
@@ -1 +1 @@
-From a121f175722f7b717cb7576c5baff1c20dd3920e Mon Sep 17 00:00:00 2001
+From 093202401799d533d5a1c17108e8028eaae85889 Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit a121f175722f7b717cb7576c5baff1c20dd3920e ]
+
@@ -17 +18,0 @@
-Cc: stable at dpdk.org
@@ -43 +44 @@
-index 83c60ea660..004802b9eb 100644
+index b6c81d6f17..269bab2f8e 100644
@@ -112 +113 @@
-@@ -142,6 +194,39 @@ vhost_vdpa_dma_unmap(struct virtio_user_dev *dev, __rte_unused void *addr,
+@@ -136,6 +188,39 @@ vhost_vdpa_dma_unmap(struct virtio_user_dev *dev, __rte_unused void *addr,
@@ -152 +153 @@
-@@ -179,21 +264,32 @@ vhost_vdpa_map(const struct rte_memseg_list *msl, const struct rte_memseg *ms,
+@@ -173,21 +258,32 @@ vhost_vdpa_map(const struct rte_memseg_list *msl, const struct rte_memseg *ms,
@@ -188 +189 @@
-@@ -313,6 +409,6 @@ struct virtio_user_backend_ops virtio_ops_vdpa = {
+@@ -307,6 +403,6 @@ struct virtio_user_backend_ops virtio_ops_vdpa = {