[dpdk-dev] [PATCH v3] vhost: Fix default value of kickfd and callfd

[Tetsuya Mukawa <mukawa@igel.co.jp>]

Currently, default values of kickfd and callfd are -1.
If the values are -1, current code guesses kickfd and callfd haven't
been initialized yet. Then vhost library will guess the virtqueue isn't
ready for processing.
But callfd and kickfd will be set as -1 when "--enable-kvm"
isn't specified in QEMU command line. It means we cannot treat -1 as
uninitialized state.
The patch defines -1 and -2 as VIRTIO_INVALID_EVENTFD and
VIRTIO_UNINITIALIZED_EVENTFD, and uses VIRTIO_UNINITIALIZED_EVENTFD for
the default values of kickfd and callfd.

Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>
---
 lib/librte_vhost/rte_virtio_net.h             |  2 ++
 lib/librte_vhost/vhost_rxtx.c                 |  9 ++++++---
 lib/librte_vhost/vhost_user/virtio-net-user.c | 14 +++++++-------
 lib/librte_vhost/virtio-net.c                 |  4 ++--
 4 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h
index 443245d..600b20b 100644
--- a/lib/librte_vhost/rte_virtio_net.h
+++ b/lib/librte_vhost/rte_virtio_net.h
@@ -89,6 +89,8 @@ struct vhost_virtqueue {
 	uint16_t		vhost_hlen;		/**< Vhost header length (varies depending on RX merge buffers. */
 	volatile uint16_t	last_used_idx;		/**< Last index used on the available ring */
 	volatile uint16_t	last_used_idx_res;	/**< Used for multiple devices reserving buffers. */
+#define VIRTIO_INVALID_EVENTFD		(-1)
+#define VIRTIO_UNINITIALIZED_EVENTFD	(-2)
 	int			callfd;			/**< Used to notify the guest (trigger interrupt). */
 	int			kickfd;			/**< Currently unused as polling mode is enabled. */
 	int			enabled;
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 9d23eb1..29d002d 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -333,7 +333,8 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
 	rte_mb();
 
 	/* Kick the guest if necessary. */
-	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+			&& (vq->callfd >= 0))
 		eventfd_write(vq->callfd, (eventfd_t)1);
 	return count;
 }
@@ -654,7 +655,8 @@ merge_rx_exit:
 		rte_mb();
 
 		/* Kick the guest if necessary. */
-		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+				&& (vq->callfd >= 0))
 			eventfd_write(vq->callfd, (eventfd_t)1);
 	}
 
@@ -1048,7 +1050,8 @@ rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
 			sizeof(vq->used->idx));
 
 	/* Kick guest if required. */
-	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+			&& (vq->callfd >= 0))
 		eventfd_write(vq->callfd, (eventfd_t)1);
 
 out:
diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
index 65b5652..f5248bc 100644
--- a/lib/librte_vhost/vhost_user/virtio-net-user.c
+++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
@@ -225,8 +225,8 @@ static int
 vq_is_ready(struct vhost_virtqueue *vq)
 {
 	return vq && vq->desc   &&
-	       vq->kickfd != -1 &&
-	       vq->callfd != -1;
+	       vq->kickfd != VIRTIO_UNINITIALIZED_EVENTFD &&
+	       vq->callfd != VIRTIO_UNINITIALIZED_EVENTFD;
 }
 
 static int
@@ -258,7 +258,7 @@ user_set_vring_call(struct vhost_device_ctx ctx, struct VhostUserMsg *pmsg)
 
 	file.index = pmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
 	if (pmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
-		file.fd = -1;
+		file.fd = VIRTIO_INVALID_EVENTFD;
 	else
 		file.fd = pmsg->fds[0];
 	RTE_LOG(INFO, VHOST_CONFIG,
@@ -279,7 +279,7 @@ user_set_vring_kick(struct vhost_device_ctx ctx, struct VhostUserMsg *pmsg)
 
 	file.index = pmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
 	if (pmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
-		file.fd = -1;
+		file.fd = VIRTIO_INVALID_EVENTFD;
 	else
 		file.fd = pmsg->fds[0];
 	RTE_LOG(INFO, VHOST_CONFIG,
@@ -316,10 +316,10 @@ user_get_vring_base(struct vhost_device_ctx ctx,
 	 * sent and only sent in vhost_vring_stop.
 	 * TODO: cleanup the vring, it isn't usable since here.
 	 */
-	if (dev->virtqueue[state->index]->kickfd >= 0) {
+	if (dev->virtqueue[state->index]->kickfd >= 0)
 		close(dev->virtqueue[state->index]->kickfd);
-		dev->virtqueue[state->index]->kickfd = -1;
-	}
+
+	dev->virtqueue[state->index]->kickfd = VIRTIO_UNINITIALIZED_EVENTFD;
 
 	return 0;
 }
diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
index 28c3912..90da9ba 100644
--- a/lib/librte_vhost/virtio-net.c
+++ b/lib/librte_vhost/virtio-net.c
@@ -167,8 +167,8 @@ init_vring_queue(struct vhost_virtqueue *vq, int qp_idx)
 {
 	memset(vq, 0, sizeof(struct vhost_virtqueue));
 
-	vq->kickfd = -1;
-	vq->callfd = -1;
+	vq->kickfd = VIRTIO_UNINITIALIZED_EVENTFD;
+	vq->callfd = VIRTIO_UNINITIALIZED_EVENTFD;
 
 	/* Backends are set to -1 indicating an inactive device. */
 	vq->backend = -1;
-- 
2.1.4