[RFC PATCH 4/5] vhost: annotate async locking requirement

[David Marchand <david.marchand@redhat.com>]

Instrument that the async field of a virtqueue must be protected by a
lock.

Signed-off-by: David Marchand <david.marchand@redhat.com>
---
 lib/vhost/vhost.c      | 14 +++++++++-----
 lib/vhost/vhost.h      |  5 ++++-
 lib/vhost/vhost_user.c |  2 ++
 lib/vhost/virtio_net.c | 14 ++++++++++++++
 4 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 9e6ca506ff..ea28323367 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -334,6 +334,7 @@ cleanup_device(struct virtio_net *dev, int destroy)
 
 static void
 vhost_free_async_mem(struct vhost_virtqueue *vq)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	if (!vq->async)
 		return;
@@ -352,6 +353,7 @@ vhost_free_async_mem(struct vhost_virtqueue *vq)
 
 void
 free_vq(struct virtio_net *dev, struct vhost_virtqueue *vq)
+	VHOST_NO_THREAD_SAFETY_ANALYSIS
 {
 	if (vq_is_packed(dev))
 		rte_free(vq->shadow_used_packed);
@@ -1622,10 +1624,10 @@ rte_vhost_extern_callback_register(int vid,
 }
 
 static __rte_always_inline int
-async_channel_register(int vid, uint16_t queue_id)
+async_channel_register(struct virtio_net *dev, struct vhost_virtqueue *vq,
+	uint16_t queue_id)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
-	struct virtio_net *dev = get_device(vid);
-	struct vhost_virtqueue *vq = dev->virtqueue[queue_id];
 	struct vhost_async *async;
 	int node = vq->numa_node;
 
@@ -1709,7 +1711,7 @@ rte_vhost_async_channel_register(int vid, uint16_t queue_id)
 		return -1;
 
 	vhost_spinlock_lock(&vq->access_lock);
-	ret = async_channel_register(vid, queue_id);
+	ret = async_channel_register(dev, vq, queue_id);
 	vhost_spinlock_unlock(&vq->access_lock);
 
 	return ret;
@@ -1717,6 +1719,7 @@ rte_vhost_async_channel_register(int vid, uint16_t queue_id)
 
 int
 rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id)
+	VHOST_NO_THREAD_SAFETY_ANALYSIS
 {
 	struct vhost_virtqueue *vq;
 	struct virtio_net *dev = get_device(vid);
@@ -1732,7 +1735,7 @@ rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id)
 	if (unlikely(vq == NULL || !dev->async_copy))
 		return -1;
 
-	return async_channel_register(vid, queue_id);
+	return async_channel_register(dev, vq, queue_id);
 }
 
 int
@@ -1777,6 +1780,7 @@ rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
 
 int
 rte_vhost_async_channel_unregister_thread_unsafe(int vid, uint16_t queue_id)
+	VHOST_NO_THREAD_SAFETY_ANALYSIS
 {
 	struct vhost_virtqueue *vq;
 	struct virtio_net *dev = get_device(vid);
diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
index 619f073fb2..4b301ec152 100644
--- a/lib/vhost/vhost.h
+++ b/lib/vhost/vhost.h
@@ -96,6 +96,8 @@
 	__attribute__((no_thread_safety_analysis))
 #define VHOST_LOCKABLE \
 	__attribute__((lockable))
+#define VHOST_GUARDED \
+	__attribute__((guarded_var))
 
 #define VHOST_SPINLOCK_REQUIRES(...) \
 	__attribute__((exclusive_locks_required(__VA_ARGS__)))
@@ -109,6 +111,7 @@
 #else
 #define VHOST_NO_THREAD_SAFETY_ANALYSIS
 #define VHOST_LOCKABLE
+#define VHOST_GUARDED
 
 #define VHOST_SPINLOCK_REQUIRES(...)
 #define VHOST_SPINLOCK_ACQUIRES(...)
@@ -363,7 +366,7 @@ struct vhost_virtqueue {
 	struct rte_vhost_resubmit_info *resubmit_inflight;
 	uint64_t		global_counter;
 
-	struct vhost_async	*async;
+	struct vhost_async	*async VHOST_GUARDED;
 
 	int			notif_enable;
 #define VIRTIO_UNINITIALIZED_NOTIF	(-1)
diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index caf4cf14b5..35f1e23995 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -2199,6 +2199,8 @@ static int
 vhost_user_set_vring_enable(struct virtio_net **pdev,
 			struct vhu_msg_context *ctx,
 			int main_fd __rte_unused)
+	/* vq->access_lock is taken in vhost_user_lock_all_queue_pairs() */
+	VHOST_NO_THREAD_SAFETY_ANALYSIS
 {
 	struct virtio_net *dev = *pdev;
 	bool enable = !!ctx->msg.payload.state.num;
diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index 25bdb1479d..9bdba992dd 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -51,6 +51,7 @@ static __rte_always_inline int64_t
 vhost_async_dma_transfer_one(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		int16_t dma_id, uint16_t vchan_id, uint16_t flag_idx,
 		struct vhost_iov_iter *pkt)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct async_dma_vchan_info *dma_info = &dma_copy_track[dma_id].vchans[vchan_id];
 	uint16_t ring_mask = dma_info->ring_mask;
@@ -99,6 +100,7 @@ static __rte_always_inline uint16_t
 vhost_async_dma_transfer(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		int16_t dma_id, uint16_t vchan_id, uint16_t head_idx,
 		struct vhost_iov_iter *pkts, uint16_t nr_pkts)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct async_dma_vchan_info *dma_info = &dma_copy_track[dma_id].vchans[vchan_id];
 	int64_t ret, nr_copies = 0;
@@ -1000,6 +1002,7 @@ static __rte_always_inline int
 async_mbuf_to_desc_seg(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		struct rte_mbuf *m, uint32_t mbuf_offset,
 		uint64_t buf_iova, uint32_t cpy_len)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct vhost_async *async = vq->async;
 	uint64_t mapped_len;
@@ -1057,6 +1060,7 @@ static __rte_always_inline int
 mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		struct rte_mbuf *m, struct buf_vector *buf_vec,
 		uint16_t nr_vec, uint16_t num_buffers, bool is_async)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	uint32_t vec_idx = 0;
 	uint32_t mbuf_offset, mbuf_avail;
@@ -1186,6 +1190,7 @@ vhost_enqueue_single_packed(struct virtio_net *dev,
 			    struct rte_mbuf *pkt,
 			    struct buf_vector *buf_vec,
 			    uint16_t *nr_descs)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	uint16_t nr_vec = 0;
 	uint16_t avail_idx = vq->last_avail_idx;
@@ -1417,6 +1422,7 @@ static __rte_always_inline int16_t
 virtio_dev_rx_single_packed(struct virtio_net *dev,
 			    struct vhost_virtqueue *vq,
 			    struct rte_mbuf *pkt)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct buf_vector buf_vec[BUF_VECTOR_MAX];
 	uint16_t nr_descs = 0;
@@ -1541,6 +1547,7 @@ rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
 
 static __rte_always_inline uint16_t
 async_get_first_inflight_pkt_idx(struct vhost_virtqueue *vq)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct vhost_async *async = vq->async;
 
@@ -1587,6 +1594,7 @@ static __rte_noinline uint32_t
 virtio_dev_rx_async_submit_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		uint16_t queue_id, struct rte_mbuf **pkts, uint32_t count,
 		int16_t dma_id, uint16_t vchan_id)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct buf_vector buf_vec[BUF_VECTOR_MAX];
 	uint32_t pkt_idx = 0;
@@ -1691,6 +1699,7 @@ vhost_enqueue_async_packed(struct virtio_net *dev,
 			    struct buf_vector *buf_vec,
 			    uint16_t *nr_descs,
 			    uint16_t *nr_buffers)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	uint16_t nr_vec = 0;
 	uint16_t avail_idx = vq->last_avail_idx;
@@ -1748,6 +1757,7 @@ vhost_enqueue_async_packed(struct virtio_net *dev,
 static __rte_always_inline int16_t
 virtio_dev_rx_async_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
 			    struct rte_mbuf *pkt, uint16_t *nr_descs, uint16_t *nr_buffers)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct buf_vector buf_vec[BUF_VECTOR_MAX];
 
@@ -1766,6 +1776,7 @@ virtio_dev_rx_async_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
 static __rte_always_inline void
 dma_error_handler_packed(struct vhost_virtqueue *vq, uint16_t slot_idx,
 			uint32_t nr_err, uint32_t *pkt_idx)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	uint16_t descs_err = 0;
 	uint16_t buffers_err = 0;
@@ -1793,6 +1804,7 @@ static __rte_noinline uint32_t
 virtio_dev_rx_async_submit_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		uint16_t queue_id, struct rte_mbuf **pkts, uint32_t count,
 		int16_t dma_id, uint16_t vchan_id)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	uint32_t pkt_idx = 0;
 	uint32_t remained = count;
@@ -1863,6 +1875,7 @@ virtio_dev_rx_async_submit_packed(struct virtio_net *dev, struct vhost_virtqueue
 
 static __rte_always_inline void
 write_back_completed_descs_split(struct vhost_virtqueue *vq, uint16_t n_descs)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct vhost_async *async = vq->async;
 	uint16_t nr_left = n_descs;
@@ -1895,6 +1908,7 @@ write_back_completed_descs_split(struct vhost_virtqueue *vq, uint16_t n_descs)
 static __rte_always_inline void
 write_back_completed_descs_packed(struct vhost_virtqueue *vq,
 				uint16_t n_buffers)
+	VHOST_SPINLOCK_REQUIRES(vq->access_lock)
 {
 	struct vhost_async *async = vq->async;
 	uint16_t from = async->last_buffer_idx_packed;
-- 
2.23.0