vhost: add flag for built-in virtio driver

The librte_vhost API is used in two ways:
1. As a vhost net device backend via rte_vhost_enqueue/dequeue_burst().
2. As a library for implementing vhost device backends.

There is no distinction between the two at the API level or in the
librte_vhost implementation.  For example, device state is kept in
"struct virtio_net" regardless of whether this is actually a net device
backend or whether the built-in virtio_net.c driver is in use.

The virtio_net.c driver should be a librte_vhost API client just like
the vhost-scsi code and have no special access to vhost.h internals.
Unfortunately, fixing this requires significant librte_vhost API
changes.

This patch takes a different approach: keep the librte_vhost API
unchanged but track whether the built-in virtio_net.c driver is in use.
See the next patch for a bug fix that requires knowledge of whether
virtio_net.c is in use.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Yuanhan Liu <yliu@fridaylinux.org>

diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
index 6e3857e..83befdc 100644 (file)
--- a/lib/librte_vhost/socket.c
+++ b/lib/librte_vhost/socket.c
@@ -40,6 +40,7 @@ struct vhost_user_socket {
        bool reconnect;
        bool dequeue_zero_copy;
        bool iommu_support;
+       bool use_builtin_virtio_net;
 
        /*
         * The "supported_features" indicates the feature bits the
@@ -195,6 +196,8 @@ vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
        size = strnlen(vsocket->path, PATH_MAX);
        vhost_set_ifname(vid, vsocket->path, size);
 
+       vhost_set_builtin_virtio_net(vid, vsocket->use_builtin_virtio_net);
+
        if (vsocket->dequeue_zero_copy)
                vhost_enable_dequeue_zero_copy(vid);
 
@@ -527,6 +530,12 @@ rte_vhost_driver_disable_features(const char *path, uint64_t features)
 
        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
+
+       /* Note that use_builtin_virtio_net is not affected by this function
+        * since callers may want to selectively disable features of the
+        * built-in vhost net device backend.
+        */
+
        if (vsocket)
                vsocket->features &= ~features;
        pthread_mutex_unlock(&vhost_user.mutex);
@@ -567,6 +576,11 @@ rte_vhost_driver_set_features(const char *path, uint64_t features)
        if (vsocket) {
                vsocket->supported_features = features;
                vsocket->features = features;
+
+               /* Anyone setting feature bits is implementing their own vhost
+                * device backend.
+                */
+               vsocket->use_builtin_virtio_net = false;
        }
        pthread_mutex_unlock(&vhost_user.mutex);
 
@@ -647,6 +661,7 @@ rte_vhost_driver_register(const char *path, uint64_t flags)
         * rte_vhost_driver_set_features(), which will overwrite following
         * two values.
         */
+       vsocket->use_builtin_virtio_net = true;
        vsocket->supported_features = VIRTIO_NET_SUPPORTED_FEATURES;
        vsocket->features           = VIRTIO_NET_SUPPORTED_FEATURES;
 

diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index 1dd9adb..a31ca50 100644 (file)
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -251,7 +251,7 @@ reset_device(struct virtio_net *dev)
 
        dev->features = 0;
        dev->protocol_features = 0;
-       dev->flags = 0;
+       dev->flags &= VIRTIO_DEV_BUILTIN_VIRTIO_NET;
 
        for (i = 0; i < dev->nr_vring; i++)
                reset_vring_queue(dev, i);
@@ -287,6 +287,7 @@ vhost_new_device(void)
 
        vhost_devices[i] = dev;
        dev->vid = i;
+       dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET;
        dev->slave_req_fd = -1;
 
        return i;
@@ -343,6 +344,20 @@ vhost_enable_dequeue_zero_copy(int vid)
        dev->dequeue_zero_copy = 1;
 }
 
+void
+vhost_set_builtin_virtio_net(int vid, bool enable)
+{
+       struct virtio_net *dev = get_device(vid);
+
+       if (dev == NULL)
+               return;
+
+       if (enable)
+               dev->flags |= VIRTIO_DEV_BUILTIN_VIRTIO_NET;
+       else
+               dev->flags &= ~VIRTIO_DEV_BUILTIN_VIRTIO_NET;
+}
+
 int
 rte_vhost_get_mtu(int vid, uint16_t *mtu)
 {

diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 646aad3..d947bc9 100644 (file)
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -24,6 +24,8 @@
 #define VIRTIO_DEV_RUNNING 1
 /* Used to indicate that the device is ready to operate */
 #define VIRTIO_DEV_READY 2
+/* Used to indicate that the built-in vhost net device backend is enabled */
+#define VIRTIO_DEV_BUILTIN_VIRTIO_NET 4
 
 /* Backend value set by guest. */
 #define VIRTIO_DEV_STOPPED -1
@@ -357,6 +359,7 @@ int alloc_vring_queue(struct virtio_net *dev, uint32_t vring_idx);
 
 void vhost_set_ifname(int, const char *if_name, unsigned int if_len);
 void vhost_enable_dequeue_zero_copy(int vid);
+void vhost_set_builtin_virtio_net(int vid, bool enable);
 
 struct vhost_device_ops const *vhost_driver_callback_get(const char *path);
 

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index edfab3b..700aca7 100644 (file)
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -703,6 +703,13 @@ rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
        if (!dev)
                return 0;
 
+       if (unlikely(!(dev->flags & VIRTIO_DEV_BUILTIN_VIRTIO_NET))) {
+               RTE_LOG(ERR, VHOST_DATA,
+                       "(%d) %s: built-in vhost net backend is disabled.\n",
+                       dev->vid, __func__);
+               return 0;
+       }
+
        if (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF))
                return virtio_dev_merge_rx(dev, queue_id, pkts, count);
        else
@@ -1128,6 +1135,13 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
        if (!dev)
                return 0;
 
+       if (unlikely(!(dev->flags & VIRTIO_DEV_BUILTIN_VIRTIO_NET))) {
+               RTE_LOG(ERR, VHOST_DATA,
+                       "(%d) %s: built-in vhost net backend is disabled.\n",
+                       dev->vid, __func__);
+               return 0;
+       }
+
        if (unlikely(!is_valid_virt_queue_idx(queue_id, 1, dev->nr_vring))) {
                RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
                        dev->vid, __func__, queue_id);