virtio: Extend vhost multi-queues support beyond 8 queue pairs

Current vhost multi-queues support has a hard limit of 8 queue pairs
due to static vring array. This limit was raised in qemu. VPP should
support more than 8 queue pairs also.

Change static vring allocation to dynamic. When the interface is
created, we allocate 8 queue pairs to begin with. We also keep track
of how many queue pairs that the interface actually uses.
We reply VHOST_USER_GET_QUEUE_NUM with 128 as our maximum number of
support queue pair. When qemu starts initializing queue pair greater
than 8, we expand the vrings as needed on demand.

Type: improvement

Signed-off-by: Steven Luong <sluong@cisco.com>
Change-Id: I4a02d987d52d1bbe601b00e71f650fe6ebfcc0d7

1 files changed, 2 insertions, 13 deletions

diff --git a/src/vnet/devices/virtio/vhost_user_output.c b/src/vnet/devices/virtio/vhost_user_output.c
index 85ac0a3c295..80eefa6d9ed 100644
--- a/src/vnet/devices/virtio/vhost_user_output.c
+++ b/src/vnet/devices/virtio/vhost_user_output.c
@@ -119,23 +119,12 @@ vhost_user_name_renumber (vnet_hw_interface_t * hi, u32 new_dev_instance)
 }
 
 /**
- * @brief Try once to lock the vring
- * @return 0 on success, non-zero on failure.
- */
-static_always_inline int
-vhost_user_vring_try_lock (vhost_user_intf_t * vui, u32 qid)
-{
-  return clib_atomic_test_and_set (vui->vring_locks[qid]);
-}
-
-/**
  * @brief Spin until the vring is successfully locked
  */
 static_always_inline void
 vhost_user_vring_lock (vhost_user_intf_t * vui, u32 qid)
 {
-  while (vhost_user_vring_try_lock (vui, qid))
-    ;
+  clib_spinlock_lock_if_init (&vui->vrings[qid].vring_lock);
 }
 
 /**
@@ -144,7 +133,7 @@ vhost_user_vring_lock (vhost_user_intf_t * vui, u32 qid)
 static_always_inline void
 vhost_user_vring_unlock (vhost_user_intf_t * vui, u32 qid)
 {
-  clib_atomic_release (vui->vring_locks[qid]);
+  clib_spinlock_unlock_if_init (&vui->vrings[qid].vring_lock);
 }
 
 static_always_inline void