From: Maxime Coquelin <maxime.coquelin@redhat.com>
Date: Tue, 8 May 2018 07:10:45 +0000 (+0800)
Subject: net/virtio-user: support memory hotplug
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=12ecb2f63b1288df2857567896ccb7a4dc3aeab2;p=dpdk.git

net/virtio-user: support memory hotplug

When memory is hot-added or hot-removed, the virtio-user driver has to
notify the vhost-user backend with sending a VHOST_USER_SET_MEM_TABLE
request with the new memory map as payload.

This patch implements and registers a mem_event callback, it pauses the
datapath and updates memory regions to vhost in case of hot-add or
hot-remove event. This memory region update has only to be done when the
device is already started, so a new status flag is added to the device to
keep track of the status.

As the device can now be managed by different threads, a mutex is
introduced to protect against concurrent device configuration.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
---

diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
index 38b8bc90d1..6522bec3f6 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
@@ -17,6 +17,8 @@
 #include "virtio_user_dev.h"
 #include "../virtio_ethdev.h"
 
+#define VIRTIO_USER_MEM_EVENT_CLB_NAME "virtio_user_mem_event_clb"
+
 static int
 virtio_user_create_queue(struct virtio_user_dev *dev, uint32_t queue_sel)
 {
@@ -110,8 +112,10 @@ virtio_user_start_device(struct virtio_user_dev *dev)
 	uint64_t features;
 	int ret;
 
+	pthread_mutex_lock(&dev->mutex);
+
 	if (is_vhost_user_by_type(dev->path) && dev->vhostfd < 0)
-		return -1;
+		goto error;
 
 	/* Do not check return as already done in init, or reset in stop */
 	dev->ops->send_request(dev, VHOST_USER_SET_OWNER, NULL);
@@ -146,8 +150,12 @@ virtio_user_start_device(struct virtio_user_dev *dev)
 	 */
 	dev->ops->enable_qp(dev, 0, 1);
 
+	dev->started = true;
+	pthread_mutex_unlock(&dev->mutex);
+
 	return 0;
 error:
+	pthread_mutex_unlock(&dev->mutex);
 	/* TODO: free resource here or caller to check */
 	return -1;
 }
@@ -156,13 +164,17 @@ int virtio_user_stop_device(struct virtio_user_dev *dev)
 {
 	uint32_t i;
 
+	pthread_mutex_lock(&dev->mutex);
 	for (i = 0; i < dev->max_queue_pairs; ++i)
 		dev->ops->enable_qp(dev, i, 0);
 
 	if (dev->ops->send_request(dev, VHOST_USER_RESET_OWNER, NULL) < 0) {
 		PMD_DRV_LOG(INFO, "Failed to reset the device\n");
+		pthread_mutex_unlock(&dev->mutex);
 		return -1;
 	}
+	dev->started = false;
+	pthread_mutex_unlock(&dev->mutex);
 
 	return 0;
 }
@@ -263,6 +275,35 @@ virtio_user_fill_intr_handle(struct virtio_user_dev *dev)
 	return 0;
 }
 
+static void
+virtio_user_mem_event_cb(enum rte_mem_event type __rte_unused,
+						 const void *addr __rte_unused,
+						 size_t len __rte_unused,
+						 void *arg)
+{
+	struct virtio_user_dev *dev = arg;
+	uint16_t i;
+
+	pthread_mutex_lock(&dev->mutex);
+
+	if (dev->started == false)
+		goto exit;
+
+	/* Step 1: pause the active queues */
+	for (i = 0; i < dev->queue_pairs; i++)
+		dev->ops->enable_qp(dev, i, 0);
+
+	/* Step 2: update memory regions */
+	dev->ops->send_request(dev, VHOST_USER_SET_MEM_TABLE, NULL);
+
+	/* Step 3: resume the active queues */
+	for (i = 0; i < dev->queue_pairs; i++)
+		dev->ops->enable_qp(dev, i, 1);
+
+exit:
+	pthread_mutex_unlock(&dev->mutex);
+}
+
 static int
 virtio_user_dev_setup(struct virtio_user_dev *dev)
 {
@@ -336,7 +377,9 @@ int
 virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
 		     int cq, int queue_size, const char *mac, char **ifname)
 {
+	pthread_mutex_init(&dev->mutex, NULL);
 	snprintf(dev->path, PATH_MAX, "%s", path);
+	dev->started = 0;
 	dev->max_queue_pairs = queues;
 	dev->queue_pairs = 1; /* mq disabled by default */
 	dev->queue_size = queue_size;
@@ -400,6 +443,12 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
 
 	dev->device_features &= VIRTIO_USER_SUPPORTED_FEATURES;
 
+	if (rte_mem_event_callback_register(VIRTIO_USER_MEM_EVENT_CLB_NAME,
+				virtio_user_mem_event_cb, dev)) {
+		PMD_INIT_LOG(ERR, "Failed to register mem event callback\n");
+		return -1;
+	}
+
 	return 0;
 }
 
@@ -410,6 +459,8 @@ virtio_user_dev_uninit(struct virtio_user_dev *dev)
 
 	virtio_user_stop_device(dev);
 
+	rte_mem_event_callback_unregister(VIRTIO_USER_MEM_EVENT_CLB_NAME, dev);
+
 	for (i = 0; i < dev->max_queue_pairs * 2; ++i) {
 		close(dev->callfds[i]);
 		close(dev->kickfds[i]);
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.h b/drivers/net/virtio/virtio_user/virtio_user_dev.h
index ade727e469..cadff0cba6 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.h
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.h
@@ -39,6 +39,8 @@ struct virtio_user_dev {
 	char		path[PATH_MAX];
 	struct vring	vrings[VIRTIO_MAX_VIRTQUEUES];
 	struct virtio_user_backend_ops *ops;
+	pthread_mutex_t	mutex;
+	bool		started;
 };
 
 int is_vhost_user_by_type(const char *path);