[dpdk-dev] [PATCH v7 7/8] vhost: add VHOST_USER_SET_VRING_ENABLE message

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

From: Changchun Ouyang <changchun.ouyang@intel.com>

This message is used to enable/disable a specific vring queue pair.
The first queue pair is enabled by default.

Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Acked-by: Flavio Leitner <fbl@sysclose.org>

---
v7: invoke vring_state_changed() callback once for each queue pair.

v6: add a vring state changed callback, for informing the application
    that a specific vring is enabled/disabled. You could either flush
    packets haven't been processed yet, or simply just drop them.
---
 lib/librte_vhost/rte_virtio_net.h             |  9 ++++++++-
 lib/librte_vhost/vhost_rxtx.c                 | 10 ++++++++++
 lib/librte_vhost/vhost_user/vhost-net-user.c  |  5 +++++
 lib/librte_vhost/vhost_user/vhost-net-user.h  |  1 +
 lib/librte_vhost/vhost_user/virtio-net-user.c | 28 +++++++++++++++++++++++++++
 lib/librte_vhost/vhost_user/virtio-net-user.h |  3 +++
 lib/librte_vhost/virtio-net.c                 | 12 +++++++++---
 7 files changed, 64 insertions(+), 4 deletions(-)

diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h
index 5dd6493..fd87f01 100644
--- a/lib/librte_vhost/rte_virtio_net.h
+++ b/lib/librte_vhost/rte_virtio_net.h
@@ -89,6 +89,7 @@ struct vhost_virtqueue {
 	volatile uint16_t	last_used_idx_res;	/**< Used for multiple devices reserving buffers. */
 	int			callfd;			/**< Used to notify the guest (trigger interrupt). */
 	int			kickfd;			/**< Currently unused as polling mode is enabled. */
+	int			enabled;
 	struct buf_vector	buf_vec[BUF_VECTOR_MAX];	/**< for scatter RX. */
 } __rte_cache_aligned;
 
@@ -132,7 +133,7 @@ struct virtio_memory {
 };
 
 /**
- * Device operations to add/remove device.
+ * Device and vring operations.
  *
  * Make sure to set VIRTIO_DEV_RUNNING to the device flags in new_device and
  * remove it in destroy_device.
@@ -141,12 +142,18 @@ struct virtio_memory {
 struct virtio_net_device_ops {
 	int (*new_device)(struct virtio_net *);	/**< Add device. */
 	void (*destroy_device)(volatile struct virtio_net *);	/**< Remove device. */
+
+	int (*vring_state_changed)(struct virtio_net *dev, uint16_t queue_id, int enable);	/**< triggered when a vring is enabled or disabled */
 };
 
 static inline uint16_t __attribute__((always_inline))
 rte_vring_available_entries(struct virtio_net *dev, uint16_t queue_id)
 {
 	struct vhost_virtqueue *vq = dev->virtqueue[queue_id];
+
+	if (vq->enabled)
+		return 0;
+
 	return *(volatile uint16_t *)&vq->avail->idx - vq->last_used_idx_res;
 }
 
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 14e00ef..400f263 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -86,6 +86,9 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
 	}
 
 	vq = dev->virtqueue[queue_id];
+	if (unlikely(vq->enabled == 0))
+		return 0;
+
 	count = (count > MAX_PKT_BURST) ? MAX_PKT_BURST : count;
 
 	/*
@@ -278,6 +281,7 @@ copy_from_mbuf_to_vring(struct virtio_net *dev, uint32_t queue_id,
 	 * (guest physical addr -> vhost virtual addr)
 	 */
 	vq = dev->virtqueue[queue_id];
+
 	vb_addr = gpa_to_vva(dev, vq->buf_vec[vec_idx].buf_addr);
 	vb_hdr_addr = vb_addr;
 
@@ -485,6 +489,9 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
 	}
 
 	vq = dev->virtqueue[queue_id];
+	if (unlikely(vq->enabled == 0))
+		return 0;
+
 	count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
 
 	if (count == 0)
@@ -586,6 +593,9 @@ rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
 	}
 
 	vq = dev->virtqueue[queue_id];
+	if (unlikely(vq->enabled == 0))
+		return 0;
+
 	avail_idx =  *((volatile uint16_t *)&vq->avail->idx);
 
 	/* If there are no available buffers then return. */
diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c b/lib/librte_vhost/vhost_user/vhost-net-user.c
index 8675cd4..f681676 100644
--- a/lib/librte_vhost/vhost_user/vhost-net-user.c
+++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
@@ -99,6 +99,7 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
 	[VHOST_USER_GET_PROTOCOL_FEATURES]  = "VHOST_USER_GET_PROTOCOL_FEATURES",
 	[VHOST_USER_SET_PROTOCOL_FEATURES]  = "VHOST_USER_SET_PROTOCOL_FEATURES",
 	[VHOST_USER_GET_QUEUE_NUM]  = "VHOST_USER_GET_QUEUE_NUM",
+	[VHOST_USER_SET_VRING_ENABLE]  = "VHOST_USER_SET_VRING_ENABLE",
 };
 
 /**
@@ -428,6 +429,10 @@ vserver_message_handler(int connfd, void *dat, int *remove)
 		send_vhost_message(connfd, &msg);
 		break;
 
+	case VHOST_USER_SET_VRING_ENABLE:
+		user_set_vring_enable(ctx, &msg.payload.state);
+		break;
+
 	default:
 		break;
 
diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.h b/lib/librte_vhost/vhost_user/vhost-net-user.h
index 389d21d..38637cc 100644
--- a/lib/librte_vhost/vhost_user/vhost-net-user.h
+++ b/lib/librte_vhost/vhost_user/vhost-net-user.h
@@ -66,6 +66,7 @@ typedef enum VhostUserRequest {
 	VHOST_USER_GET_PROTOCOL_FEATURES = 15,
 	VHOST_USER_SET_PROTOCOL_FEATURES = 16,
 	VHOST_USER_GET_QUEUE_NUM = 17,
+	VHOST_USER_SET_VRING_ENABLE = 18,
 	VHOST_USER_MAX
 } VhostUserRequest;
 
diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
index e83d279..dfddc43 100644
--- a/lib/librte_vhost/vhost_user/virtio-net-user.c
+++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
@@ -306,6 +306,34 @@ user_get_vring_base(struct vhost_device_ctx ctx,
 	return 0;
 }
 
+/*
+ * when virtio queues are ready to work, qemu will send us to
+ * enable the virtio queue pair.
+ */
+int
+user_set_vring_enable(struct vhost_device_ctx ctx,
+		      struct vhost_vring_state *state)
+{
+	struct virtio_net *dev = get_device(ctx);
+	uint16_t base_idx = state->index;
+	int enable = (int)state->num;
+
+	RTE_LOG(INFO, VHOST_CONFIG,
+		"set queue enable: %d to qp idx: %d\n",
+		enable, state->index);
+
+	if (dev->protocol_features & (1 << VHOST_USER_PROTOCOL_F_MQ) &&
+	    notify_ops->vring_state_changed) {
+		notify_ops->vring_state_changed(dev, base_idx / VIRTIO_QNUM,
+						enable);
+	}
+
+	dev->virtqueue[base_idx + VIRTIO_RXQ]->enabled = enable;
+	dev->virtqueue[base_idx + VIRTIO_TXQ]->enabled = enable;
+
+	return 0;
+}
+
 void
 user_destroy_device(struct vhost_device_ctx ctx)
 {
diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.h b/lib/librte_vhost/vhost_user/virtio-net-user.h
index 5f6d667..b82108d 100644
--- a/lib/librte_vhost/vhost_user/virtio-net-user.h
+++ b/lib/librte_vhost/vhost_user/virtio-net-user.h
@@ -52,5 +52,8 @@ void user_set_protocol_features(struct vhost_device_ctx ctx,
 
 int user_get_vring_base(struct vhost_device_ctx, struct vhost_vring_state *);
 
+int user_set_vring_enable(struct vhost_device_ctx ctx,
+			  struct vhost_vring_state *state);
+
 void user_destroy_device(struct vhost_device_ctx);
 #endif
diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
index d644022..b11fd61 100644
--- a/lib/librte_vhost/virtio-net.c
+++ b/lib/librte_vhost/virtio-net.c
@@ -255,7 +255,7 @@ rm_config_ll_entry(struct virtio_net_config_ll *ll_dev,
 }
 
 static void
-init_vring_queue(struct vhost_virtqueue *vq)
+init_vring_queue(struct vhost_virtqueue *vq, int qp_idx)
 {
 	memset(vq, 0, sizeof(struct vhost_virtqueue));
 
@@ -264,13 +264,19 @@ init_vring_queue(struct vhost_virtqueue *vq)
 
 	/* Backends are set to -1 indicating an inactive device. */
 	vq->backend = -1;
+
+	/* always set the default vq pair to enabled */
+	if (qp_idx == 0)
+		vq->enabled = 1;
 }
 
 static void
 init_vring_queue_pair(struct virtio_net *dev, uint32_t qp_idx)
 {
-	init_vring_queue(dev->virtqueue[qp_idx * VIRTIO_QNUM + VIRTIO_RXQ]);
-	init_vring_queue(dev->virtqueue[qp_idx * VIRTIO_QNUM + VIRTIO_TXQ]);
+	uint32_t base_idx = qp_idx * VIRTIO_QNUM;
+
+	init_vring_queue(dev->virtqueue[base_idx + VIRTIO_RXQ], qp_idx);
+	init_vring_queue(dev->virtqueue[base_idx + VIRTIO_TXQ], qp_idx);
 }
 
 static int
-- 
1.9.0