[dpdk-dev] [PATCH v4 1/2] vhost: add packed ring support to vring base requests

[Maxime Coquelin <maxime.coquelin@redhat.com>]

For packed ring layout, we need save avail index and its wrap
counter value. At restore time, the used index and its wrap counter
are set to available's ones, as the ring procressing is stopped
at vring base get time.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost_user.c | 40 +++++++++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 508228a3c..cc154f312 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -696,10 +696,27 @@ vhost_user_set_vring_base(struct virtio_net **pdev,
 			int main_fd __rte_unused)
 {
 	struct virtio_net *dev = *pdev;
-	dev->virtqueue[msg->payload.state.index]->last_used_idx  =
-			msg->payload.state.num;
-	dev->virtqueue[msg->payload.state.index]->last_avail_idx =
-			msg->payload.state.num;
+	struct vhost_virtqueue *vq = dev->virtqueue[msg->payload.state.index];
+	uint64_t val = msg->payload.state.num;
+
+	if (vq_is_packed(dev)) {
+		/*
+		 * Bit[0:14]: avail index
+		 * Bit[15]: avail wrap counter
+		 */
+		vq->last_avail_idx = val & 0x7fff;
+		vq->avail_wrap_counter = !!(val & (0x1 << 15));
+		/*
+		 * Set used index to same value as available one, as
+		 * their values should be the same since ring processing
+		 * was stopped at get time.
+		 */
+		vq->last_used_idx = vq->last_avail_idx;
+		vq->used_wrap_counter = vq->avail_wrap_counter;
+	} else {
+		vq->last_used_idx = msg->payload.state.num;
+		vq->last_avail_idx = msg->payload.state.num;
+	}
 
 	return VH_RESULT_OK;
 }
@@ -1208,6 +1225,7 @@ vhost_user_get_vring_base(struct virtio_net **pdev,
 {
 	struct virtio_net *dev = *pdev;
 	struct vhost_virtqueue *vq = dev->virtqueue[msg->payload.state.index];
+	uint64_t val;
 
 	/* We have to stop the queue (virtio) if it is running. */
 	vhost_destroy_device_notify(dev);
@@ -1215,8 +1233,18 @@ vhost_user_get_vring_base(struct virtio_net **pdev,
 	dev->flags &= ~VIRTIO_DEV_READY;
 	dev->flags &= ~VIRTIO_DEV_VDPA_CONFIGURED;
 
-	/* Here we are safe to get the last avail index */
-	msg->payload.state.num = vq->last_avail_idx;
+	/* Here we are safe to get the indexes */
+	if (vq_is_packed(dev)) {
+		/*
+		 * Bit[0:14]: avail index
+		 * Bit[15]: avail wrap counter
+		 */
+		val = vq->last_avail_idx & 0x7fff;
+		val |= vq->avail_wrap_counter << 15;
+		msg->payload.state.num = val;
+	} else {
+		msg->payload.state.num = vq->last_avail_idx;
+	}
 
 	RTE_LOG(INFO, VHOST_CONFIG,
 		"vring base idx:%d file:%d\n", msg->payload.state.index,
-- 
2.17.2