[PATCH AUTOSEL 5.9 19/33] vhost: add helper to check if a vq has been setup

[Sasha Levin <sashal@kernel.org>]

From: Mike Christie <michael.christie@oracle.com>

[ Upstream commit 6bcf34224ac1e94103797fd68b9836061762f2b2 ]

This adds a helper check if a vq has been setup. The next patches
will use this when we move the vhost scsi cmd preallocation from per
session to per vq. In the per vq case, we only want to allocate cmds
for vqs that have actually been setup and not for all the possible
vqs.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Link: https://lore.kernel.org/r/1604986403-4931-2-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/vhost/vhost.c | 6 ++++++
 drivers/vhost/vhost.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 9ad45e1d27f0f..23e7b2d624511 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -305,6 +305,12 @@ static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
 	spin_lock_init(&call_ctx->ctx_lock);
 }
 
+bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
+{
+	return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
+}
+EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
+
 static void vhost_vq_reset(struct vhost_dev *dev,
 			   struct vhost_virtqueue *vq)
 {
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 9032d3c2a9f48..3d30b3da7bcf5 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -190,6 +190,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *,
 		      struct vhost_log *log, unsigned int *log_num);
 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 
+bool vhost_vq_is_setup(struct vhost_virtqueue *vq);
 int vhost_vq_init_access(struct vhost_virtqueue *);
 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
-- 
2.27.0