vdpa/mlx5: fix queue update synchronization

The driver CQ event management is done by non vhost library thread,
either the dpdk host thread or the internal vDPA driver thread.

When a queue is updated the CQ may be destroyed and created by the vhost
library thread via the queue state operation.

When the queue update feature was added, it didn't synchronize the CQ
management to the queue update what may cause invalid memory access.

Add the aforementioned synchronization by a new per device configuration
mutex.

Fixes: c47d6e8333 ("vdpa/mlx5: support queue update")

Signed-off-by: Xueming Li <xuemingl@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

drivers/vdpa/mlx5/mlx5_vdpa.c

@@ -133,6 +133,7 @@ mlx5_vdpa_set_vring_state(int vid, int vring, int state)
 	struct rte_vdpa_device *vdev = rte_vhost_get_vdpa_device(vid);
 	struct mlx5_vdpa_priv *priv =
 		mlx5_vdpa_find_priv_resource_by_vdev(vdev);
+	int ret;
 
 	if (priv == NULL) {
 		DRV_LOG(ERR, "Invalid vDPA device: %s.", vdev->device->name);
@@ -142,7 +143,10 @@ mlx5_vdpa_set_vring_state(int vid, int vring, int state)
 		DRV_LOG(ERR, "Too big vring id: %d.", vring);
 		return -E2BIG;
 	}
-	return mlx5_vdpa_virtq_enable(priv, vring, state);
+	pthread_mutex_lock(&priv->vq_config_lock);
+	ret = mlx5_vdpa_virtq_enable(priv, vring, state);
+	pthread_mutex_unlock(&priv->vq_config_lock);
+	return ret;
 }
 
 static int
@@ -742,6 +746,7 @@ mlx5_vdpa_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	}
 	mlx5_vdpa_config_get(pci_dev->device.devargs, priv);
 	SLIST_INIT(&priv->mr_list);
+	pthread_mutex_init(&priv->vq_config_lock, NULL);
 	pthread_mutex_lock(&priv_list_lock);
 	TAILQ_INSERT_TAIL(&priv_list, priv, next);
 	pthread_mutex_unlock(&priv_list_lock);
@@ -793,6 +798,7 @@ mlx5_vdpa_pci_remove(struct rte_pci_device *pci_dev)
 			priv->var = NULL;
 		}
 		mlx5_glue->close_device(priv->ctx);
+		pthread_mutex_destroy(&priv->vq_config_lock);
 		rte_free(priv);
 	}
 	return 0;

drivers/vdpa/mlx5/mlx5_vdpa.h

@@ -120,6 +120,7 @@ enum {
 struct mlx5_vdpa_priv {
 	TAILQ_ENTRY(mlx5_vdpa_priv) next;
 	uint8_t configured;
+	pthread_mutex_t vq_config_lock;
 	uint64_t last_traffic_tic;
 	pthread_t timer_tid;
 	pthread_mutex_t timer_lock;

drivers/vdpa/mlx5/mlx5_vdpa_event.c

@@ -274,6 +274,7 @@ mlx5_vdpa_poll_handle(void *arg)
 								 priv->event_us;
 	while (1) {
 		max = 0;
+		pthread_mutex_lock(&priv->vq_config_lock);
 		for (i = 0; i < priv->nr_virtqs; i++) {
 			cq = &priv->virtqs[i].eqp.cq;
 			if (cq->cq && !cq->armed) {
@@ -297,6 +298,7 @@ mlx5_vdpa_poll_handle(void *arg)
 				DRV_LOG(DEBUG, "Device %s traffic was stopped.",
 					priv->vdev->device->name);
 				mlx5_vdpa_arm_all_cqs(priv);
+				pthread_mutex_unlock(&priv->vq_config_lock);
 				pthread_mutex_lock(&priv->timer_lock);
 				priv->timer_on = 0;
 				while (!priv->timer_on)
@@ -312,6 +314,7 @@ mlx5_vdpa_poll_handle(void *arg)
 		} else {
 			priv->last_traffic_tic = current_tic;
 		}
+		pthread_mutex_unlock(&priv->vq_config_lock);
 		mlx5_vdpa_timer_sleep(priv, max);
 	}
 	return NULL;
@@ -327,6 +330,7 @@ mlx5_vdpa_interrupt_handler(void *cb_arg)
 		uint8_t buf[sizeof(struct mlx5dv_devx_async_event_hdr) + 128];
 	} out;
 
+	pthread_mutex_lock(&priv->vq_config_lock);
 	while (mlx5_glue->devx_get_event(priv->eventc, &out.event_resp,
 					 sizeof(out.buf)) >=
 				       (ssize_t)sizeof(out.event_resp.cookie)) {
@@ -337,12 +341,15 @@ mlx5_vdpa_interrupt_handler(void *cb_arg)
 		struct mlx5_vdpa_virtq *virtq = container_of(eqp,
 						   struct mlx5_vdpa_virtq, eqp);
 
+		if (!virtq->enable)
+			continue;
 		mlx5_vdpa_cq_poll(cq);
 		/* Notify guest for descs consuming. */
 		if (cq->callfd != -1)
 			eventfd_write(cq->callfd, (eventfd_t)1);
 		if (priv->event_mode == MLX5_VDPA_EVENT_MODE_ONLY_INTERRUPT) {
 			mlx5_vdpa_cq_arm(priv, cq);
+			pthread_mutex_unlock(&priv->vq_config_lock);
 			return;
 		}
 		/* Don't arm again - timer will take control. */
@@ -363,6 +370,7 @@ mlx5_vdpa_interrupt_handler(void *cb_arg)
 		pthread_cond_signal(&priv->timer_cond);
 	}
 	pthread_mutex_unlock(&priv->timer_lock);
+	pthread_mutex_unlock(&priv->vq_config_lock);
 }
 
 int