[dpdk-dev] [PATCH v4 10/22] vhost: export the number of vrings

[Yuanhan Liu]

We used to use rte_vhost_get_queue_num() for telling how many vrings.
However, the return value is the number of "queue pairs", which is
very virtio-net specific. To make it generic, we should return the
number of vrings instead, and let the driver do the proper translation.
Say, virtio-net driver could turn it to the number of queue pairs by
dividing 2.

Meanwhile, mark rte_vhost_get_queue_num as deprecated.

Signed-off-by: Yuanhan Liu <yuanhan....@linux.intel.com>
Reviewed-by: Maxime Coquelin <maxime.coque...@redhat.com>
---
v2: - update release note
---
 doc/guides/rel_notes/release_17_05.rst |  3 +++
 drivers/net/vhost/rte_eth_vhost.c      |  2 +-
 lib/librte_vhost/rte_vhost_version.map |  1 +
 lib/librte_vhost/rte_virtio_net.h      | 17 +++++++++++++++++
 lib/librte_vhost/vhost.c               | 11 +++++++++++
 5 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/doc/guides/rel_notes/release_17_05.rst 
b/doc/guides/rel_notes/release_17_05.rst
index 2a4a480..5dc5b87 100644
--- a/doc/guides/rel_notes/release_17_05.rst
+++ b/doc/guides/rel_notes/release_17_05.rst
@@ -208,6 +208,9 @@ API Changes
     be per vhost-user socket file. Thus, it takes one more argument:
     ``rte_vhost_driver_callback_register(path, ops)``.
 
+  * The vhost API ``rte_vhost_get_queue_num`` is deprecated, instead,
+    ``rte_vhost_get_vring_num`` should be used.
+
 
 ABI Changes
 -----------
diff --git a/drivers/net/vhost/rte_eth_vhost.c 
b/drivers/net/vhost/rte_eth_vhost.c
index 7504f89..5435bd6 100644
--- a/drivers/net/vhost/rte_eth_vhost.c
+++ b/drivers/net/vhost/rte_eth_vhost.c
@@ -569,7 +569,7 @@ struct vhost_xstats_name_off {
                vq->port = eth_dev->data->port_id;
        }
 
-       for (i = 0; i < rte_vhost_get_queue_num(vid) * VIRTIO_QNUM; i++)
+       for (i = 0; i < rte_vhost_get_vring_num(vid); i++)
                rte_vhost_enable_guest_notification(vid, i, 0);
 
        rte_vhost_get_mtu(vid, &eth_dev->data->mtu);
diff --git a/lib/librte_vhost/rte_vhost_version.map 
b/lib/librte_vhost/rte_vhost_version.map
index 2b309b2..8df14dc 100644
--- a/lib/librte_vhost/rte_vhost_version.map
+++ b/lib/librte_vhost/rte_vhost_version.map
@@ -39,6 +39,7 @@ DPDK_17.05 {
        rte_vhost_get_mtu;
        rte_vhost_get_negotiated_features;
        rte_vhost_get_vhost_vring;
+       rte_vhost_get_vring_num;
        rte_vhost_gpa_to_vva;
 
 } DPDK_16.07;
diff --git a/lib/librte_vhost/rte_virtio_net.h 
b/lib/librte_vhost/rte_virtio_net.h
index e019f98..9c1809e 100644
--- a/lib/librte_vhost/rte_virtio_net.h
+++ b/lib/librte_vhost/rte_virtio_net.h
@@ -241,17 +241,34 @@ int rte_vhost_driver_callback_register(const char *path,
 int rte_vhost_get_numa_node(int vid);
 
 /**
+ * @deprecated
  * Get the number of queues the device supports.
  *
+ * Note this function is deprecated, as it returns a queue pair number,
+ * which is virtio-net specific. Instead, rte_vhost_get_vring_num should
+ * be used.
+ *
  * @param vid
  *  virtio-net device ID
  *
  * @return
  *  The number of queues, 0 on failure
  */
+__rte_deprecated
 uint32_t rte_vhost_get_queue_num(int vid);
 
 /**
+ * Get the number of vrings the device supports.
+ *
+ * @param vid
+ *  vhost device ID
+ *
+ * @return
+ *  The number of vrings, 0 on failure
+ */
+uint16_t rte_vhost_get_vring_num(int vid);
+
+/**
  * Get the virtio net device's ifname, which is the vhost-user socket
  * file path.
  *
diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index f0ed729..d57d4b2 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -317,6 +317,17 @@ struct virtio_net *
        return dev->nr_vring / 2;
 }
 
+uint16_t
+rte_vhost_get_vring_num(int vid)
+{
+       struct virtio_net *dev = get_device(vid);
+
+       if (dev == NULL)
+               return 0;
+
+       return dev->nr_vring;
+}
+
 int
 rte_vhost_get_ifname(int vid, char *buf, size_t len)
 {
-- 
1.9.0