vhost: support host notifier

When a vDPA device is attached, vhost user will try to
register host notifiers to QEMU to allow notifications
to be delivered between the driver in the guest and the
vDPA device in the host directly.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

lib/librte_vhost/rte_vhost.h

@@ -58,6 +58,14 @@ extern "C" {
 #define VHOST_USER_PROTOCOL_F_CRYPTO_SESSION 7
 #endif
 
+#ifndef VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD
+#define VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD 10
+#endif
+
+#ifndef VHOST_USER_PROTOCOL_F_HOST_NOTIFIER
+#define VHOST_USER_PROTOCOL_F_HOST_NOTIFIER 11
+#endif
+
 /** Indicate whether protocol features negotiation is supported. */
 #ifndef VHOST_USER_F_PROTOCOL_FEATURES
 #define VHOST_USER_F_PROTOCOL_FEATURES	30

lib/librte_vhost/vhost.c

@@ -291,6 +291,7 @@ vhost_new_device(void)
 	dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET;
 	dev->slave_req_fd = -1;
 	dev->vdpa_dev_id = -1;
+	rte_spinlock_init(&dev->slave_req_lock);
 
 	return i;
 }
@@ -346,6 +347,8 @@ vhost_detach_vdpa_device(int vid)
 	if (dev == NULL)
 		return;
 
+	vhost_user_host_notifier_ctrl(vid, false);
+
 	dev->vdpa_dev_id = -1;
 }
 

lib/librte_vhost/vhost.h

@@ -301,6 +301,7 @@ struct virtio_net {
 	struct guest_page       *guest_pages;
 
 	int			slave_req_fd;
+	rte_spinlock_t		slave_req_lock;
 
 	/*
 	 * Device id to identify a specific backend device.

lib/librte_vhost/vhost_user.c

@@ -1384,6 +1384,22 @@ send_vhost_reply(int sockfd, struct VhostUserMsg *msg)
 	return send_vhost_message(sockfd, msg, NULL, 0);
 }
 
+static int
+send_vhost_slave_message(struct virtio_net *dev, struct VhostUserMsg *msg,
+			 int *fds, int fd_num)
+{
+	int ret;
+
+	if (msg->flags & VHOST_USER_NEED_REPLY)
+		rte_spinlock_lock(&dev->slave_req_lock);
+
+	ret = send_vhost_message(dev->slave_req_fd, msg, fds, fd_num);
+	if (ret < 0 && (msg->flags & VHOST_USER_NEED_REPLY))
+		rte_spinlock_unlock(&dev->slave_req_lock);
+
+	return ret;
+}
+
 /*
  * Allocate a queue pair if it hasn't been allocated yet
  */
@@ -1705,11 +1721,45 @@ skip_to_reply:
 		if (vdpa_dev->ops->dev_conf)
 			vdpa_dev->ops->dev_conf(dev->vid);
 		dev->flags |= VIRTIO_DEV_VDPA_CONFIGURED;
+		if (vhost_user_host_notifier_ctrl(dev->vid, true) != 0) {
+			RTE_LOG(INFO, VHOST_CONFIG,
+				"(%d) software relay is used for vDPA, performance may be low.\n",
+				dev->vid);
+		}
 	}
 
 	return 0;
 }
 
+static int process_slave_message_reply(struct virtio_net *dev,
+				       const VhostUserMsg *msg)
+{
+	VhostUserMsg msg_reply;
+	int ret;
+
+	if ((msg->flags & VHOST_USER_NEED_REPLY) == 0)
+		return 0;
+
+	if (read_vhost_message(dev->slave_req_fd, &msg_reply) < 0) {
+		ret = -1;
+		goto out;
+	}
+
+	if (msg_reply.request.slave != msg->request.slave) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"Received unexpected msg type (%u), expected %u\n",
+			msg_reply.request.slave, msg->request.slave);
+		ret = -1;
+		goto out;
+	}
+
+	ret = msg_reply.payload.u64 ? -1 : 0;
+
+out:
+	rte_spinlock_unlock(&dev->slave_req_lock);
+	return ret;
+}
+
 int
 vhost_user_iotlb_miss(struct virtio_net *dev, uint64_t iova, uint8_t perm)
 {
@@ -1735,3 +1785,99 @@ vhost_user_iotlb_miss(struct virtio_net *dev, uint64_t iova, uint8_t perm)
 
 	return 0;
 }
+
+static int vhost_user_slave_set_vring_host_notifier(struct virtio_net *dev,
+						    int index, int fd,
+						    uint64_t offset,
+						    uint64_t size)
+{
+	int *fdp = NULL;
+	size_t fd_num = 0;
+	int ret;
+	struct VhostUserMsg msg = {
+		.request.slave = VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG,
+		.flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY,
+		.size = sizeof(msg.payload.area),
+		.payload.area = {
+			.u64 = index & VHOST_USER_VRING_IDX_MASK,
+			.size = size,
+			.offset = offset,
+		},
+	};
+
+	if (fd < 0)
+		msg.payload.area.u64 |= VHOST_USER_VRING_NOFD_MASK;
+	else {
+		fdp = &fd;
+		fd_num = 1;
+	}
+
+	ret = send_vhost_slave_message(dev, &msg, fdp, fd_num);
+	if (ret < 0) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"Failed to set host notifier (%d)\n", ret);
+		return ret;
+	}
+
+	return process_slave_message_reply(dev, &msg);
+}
+
+int vhost_user_host_notifier_ctrl(int vid, bool enable)
+{
+	struct virtio_net *dev;
+	struct rte_vdpa_device *vdpa_dev;
+	int vfio_device_fd, did, ret = 0;
+	uint64_t offset, size;
+	unsigned int i;
+
+	dev = get_device(vid);
+	if (!dev)
+		return -ENODEV;
+
+	did = dev->vdpa_dev_id;
+	if (did < 0)
+		return -EINVAL;
+
+	if (!(dev->features & (1ULL << VIRTIO_F_VERSION_1)) ||
+	    !(dev->features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES)) ||
+	    !(dev->protocol_features &
+			(1ULL << VHOST_USER_PROTOCOL_F_SLAVE_REQ)) ||
+	    !(dev->protocol_features &
+			(1ULL << VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD)) ||
+	    !(dev->protocol_features &
+			(1ULL << VHOST_USER_PROTOCOL_F_HOST_NOTIFIER)))
+		return -ENOTSUP;
+
+	vdpa_dev = rte_vdpa_get_device(did);
+
+	RTE_FUNC_PTR_OR_ERR_RET(vdpa_dev->ops->get_vfio_device_fd, -ENOTSUP);
+	RTE_FUNC_PTR_OR_ERR_RET(vdpa_dev->ops->get_notify_area, -ENOTSUP);
+
+	vfio_device_fd = vdpa_dev->ops->get_vfio_device_fd(vid);
+	if (vfio_device_fd < 0)
+		return -ENOTSUP;
+
+	if (enable) {
+		for (i = 0; i < dev->nr_vring; i++) {
+			if (vdpa_dev->ops->get_notify_area(vid, i, &offset,
+					&size) < 0) {
+				ret = -ENOTSUP;
+				goto disable;
+			}
+
+			if (vhost_user_slave_set_vring_host_notifier(dev, i,
+					vfio_device_fd, offset, size) < 0) {
+				ret = -EFAULT;
+				goto disable;
+			}
+		}
+	} else {
+disable:
+		for (i = 0; i < dev->nr_vring; i++) {
+			vhost_user_slave_set_vring_host_notifier(dev, i, -1,
+					0, 0);
+		}
+	}
+
+	return ret;
+}

lib/librte_vhost/vhost_user.h

@@ -20,7 +20,9 @@
 					 (1ULL << VHOST_USER_PROTOCOL_F_REPLY_ACK) | \
 					 (1ULL << VHOST_USER_PROTOCOL_F_NET_MTU) | \
 					 (1ULL << VHOST_USER_PROTOCOL_F_SLAVE_REQ) | \
-					 (1ULL << VHOST_USER_PROTOCOL_F_CRYPTO_SESSION))
+					 (1ULL << VHOST_USER_PROTOCOL_F_CRYPTO_SESSION) | \
+					 (1ULL << VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD) | \
+					 (1ULL << VHOST_USER_PROTOCOL_F_HOST_NOTIFIER))
 
 typedef enum VhostUserRequest {
 	VHOST_USER_NONE = 0,
@@ -54,6 +56,7 @@ typedef enum VhostUserRequest {
 typedef enum VhostUserSlaveRequest {
 	VHOST_USER_SLAVE_NONE = 0,
 	VHOST_USER_SLAVE_IOTLB_MSG = 1,
+	VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
 	VHOST_USER_SLAVE_MAX
 } VhostUserSlaveRequest;
 
@@ -99,6 +102,12 @@ typedef struct VhostUserCryptoSessionParam {
 	uint8_t auth_key_buf[VHOST_USER_CRYPTO_MAX_HMAC_KEY_LENGTH];
 } VhostUserCryptoSessionParam;
 
+typedef struct VhostUserVringArea {
+	uint64_t u64;
+	uint64_t size;
+	uint64_t offset;
+} VhostUserVringArea;
+
 typedef struct VhostUserMsg {
 	union {
 		uint32_t master; /* a VhostUserRequest value */
@@ -120,6 +129,7 @@ typedef struct VhostUserMsg {
 		VhostUserLog    log;
 		struct vhost_iotlb_msg iotlb;
 		VhostUserCryptoSessionParam crypto_session;
+		VhostUserVringArea area;
 	} payload;
 	int fds[VHOST_MEMORY_MAX_NREGIONS];
 } __attribute((packed)) VhostUserMsg;
@@ -133,6 +143,7 @@ typedef struct VhostUserMsg {
 /* vhost_user.c */
 int vhost_user_msg_handler(int vid, int fd);
 int vhost_user_iotlb_miss(struct virtio_net *dev, uint64_t iova, uint8_t perm);
+int vhost_user_host_notifier_ctrl(int vid, bool enable);
 
 /* socket.c */
 int read_fd_message(int sockfd, char *buf, int buflen, int *fds, int fd_num);