From c276398e43bec444eb207c3184f667b3d97361f8 Mon Sep 17 00:00:00 2001
From: Tiwei Bie <tiwei.bie@intel.com>
Date: Wed, 23 Jan 2019 01:01:40 +0800
Subject: [PATCH 16/18] net/virtio: fix control VQ

[ upstream commit 2923b8f9c41da37d63bd196ba2f037c154a6ebd5 ]

This patch mainly fixed below issues in the packed ring based
control vq support in virtio driver:

1. When parsing the used descriptors, we have to track the
   number of descs that we need to skip;
2. vq->vq_free_cnt was decreased twice for a same desc;

Meanwhile, make the function name consistent with other parts.

Fixes: ec194c2f1895 ("net/virtio: support packed queue in send command")
Fixes: a4270ea4ff79 ("net/virtio: check head desc with correct wrap counter")

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
[changed parameters to virtio_rmb/_wmb()]
(cherry picked from commit 2923b8f9c41da37d63bd196ba2f037c154a6ebd5)
Signed-off-by: Jens Freimann <jfreimann@redhat.com>
---
 drivers/net/virtio/virtio_ethdev.c | 62 ++++++++++++++----------------
 drivers/net/virtio/virtqueue.h     | 12 +-----
 2 files changed, 31 insertions(+), 43 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 7bd38a292..c12fb157e 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -142,16 +142,17 @@ static const struct rte_virtio_xstats_name_off rte_virtio_txq_stat_strings[] = {
 struct virtio_hw_internal virtio_hw_internal[RTE_MAX_ETHPORTS];
 
 static struct virtio_pmd_ctrl *
-virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
-		       int *dlen, int pkt_num)
+virtio_send_command_packed(struct virtnet_ctl *cvq,
+			   struct virtio_pmd_ctrl *ctrl,
+			   int *dlen, int pkt_num)
 {
 	struct virtqueue *vq = cvq->vq;
 	int head;
 	struct vring_packed_desc *desc = vq->ring_packed.desc_packed;
 	struct virtio_pmd_ctrl *result;
-	bool avail_wrap_counter, used_wrap_counter;
-	uint16_t flags;
+	bool avail_wrap_counter;
 	int sum = 0;
+	int nb_descs = 0;
 	int k;
 
 	/*
@@ -162,11 +163,10 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
 	 */
 	head = vq->vq_avail_idx;
 	avail_wrap_counter = vq->avail_wrap_counter;
-	used_wrap_counter = vq->used_wrap_counter;
-	desc[head].flags = VRING_DESC_F_NEXT;
 	desc[head].addr = cvq->virtio_net_hdr_mem;
 	desc[head].len = sizeof(struct virtio_net_ctrl_hdr);
 	vq->vq_free_cnt--;
+	nb_descs++;
 	if (++vq->vq_avail_idx >= vq->vq_nentries) {
 		vq->vq_avail_idx -= vq->vq_nentries;
 		vq->avail_wrap_counter ^= 1;
@@ -177,55 +177,51 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
 			+ sizeof(struct virtio_net_ctrl_hdr)
 			+ sizeof(ctrl->status) + sizeof(uint8_t) * sum;
 		desc[vq->vq_avail_idx].len = dlen[k];
-		flags = VRING_DESC_F_NEXT;
+		desc[vq->vq_avail_idx].flags = VRING_DESC_F_NEXT |
+			VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
+			VRING_DESC_F_USED(!vq->avail_wrap_counter);
 		sum += dlen[k];
 		vq->vq_free_cnt--;
-		flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
-			 VRING_DESC_F_USED(!vq->avail_wrap_counter);
-		desc[vq->vq_avail_idx].flags = flags;
-		rte_smp_wmb();
-		vq->vq_free_cnt--;
+		nb_descs++;
 		if (++vq->vq_avail_idx >= vq->vq_nentries) {
 			vq->vq_avail_idx -= vq->vq_nentries;
 			vq->avail_wrap_counter ^= 1;
 		}
 	}
 
-
 	desc[vq->vq_avail_idx].addr = cvq->virtio_net_hdr_mem
 		+ sizeof(struct virtio_net_ctrl_hdr);
 	desc[vq->vq_avail_idx].len = sizeof(ctrl->status);
-	flags = VRING_DESC_F_WRITE;
-	flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
-		 VRING_DESC_F_USED(!vq->avail_wrap_counter);
-	desc[vq->vq_avail_idx].flags = flags;
-	flags = VRING_DESC_F_NEXT;
-	flags |= VRING_DESC_F_AVAIL(avail_wrap_counter) |
-		 VRING_DESC_F_USED(!avail_wrap_counter);
-	desc[head].flags = flags;
-	rte_smp_wmb();
-
+	desc[vq->vq_avail_idx].flags = VRING_DESC_F_WRITE |
+		VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
+		VRING_DESC_F_USED(!vq->avail_wrap_counter);
 	vq->vq_free_cnt--;
+	nb_descs++;
 	if (++vq->vq_avail_idx >= vq->vq_nentries) {
 		vq->vq_avail_idx -= vq->vq_nentries;
 		vq->avail_wrap_counter ^= 1;
 	}
 
+	virtio_wmb();
+	desc[head].flags = VRING_DESC_F_NEXT |
+		VRING_DESC_F_AVAIL(avail_wrap_counter) |
+		VRING_DESC_F_USED(!avail_wrap_counter);
+
+	virtio_wmb();
 	virtqueue_notify(vq);
 
 	/* wait for used descriptors in virtqueue */
-	do {
-		rte_rmb();
+	while (!desc_is_used(&desc[head], vq))
 		usleep(100);
-	} while (!__desc_is_used(&desc[head], used_wrap_counter));
+
+	virtio_rmb();
 
 	/* now get used descriptors */
-	while (desc_is_used(&desc[vq->vq_used_cons_idx], vq)) {
-		vq->vq_free_cnt++;
-		if (++vq->vq_used_cons_idx >= vq->vq_nentries) {
-			vq->vq_used_cons_idx -= vq->vq_nentries;
-			vq->used_wrap_counter ^= 1;
-		}
+	vq->vq_free_cnt += nb_descs;
+	vq->vq_used_cons_idx += nb_descs;
+	if (vq->vq_used_cons_idx >= vq->vq_nentries) {
+		vq->vq_used_cons_idx -= vq->vq_nentries;
+		vq->used_wrap_counter ^= 1;
 	}
 
 	result = cvq->virtio_net_hdr_mz->addr;
@@ -266,7 +262,7 @@ virtio_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
 		sizeof(struct virtio_pmd_ctrl));
 
 	if (vtpci_packed_queue(vq->hw)) {
-		result = virtio_pq_send_command(cvq, ctrl, dlen, pkt_num);
+		result = virtio_send_command_packed(cvq, ctrl, dlen, pkt_num);
 		goto out_unlock;
 	}
 
diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 75f5782bc..9e74b7bd0 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -256,7 +256,7 @@ struct virtio_tx_region {
 };
 
 static inline int
-__desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
+desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
 {
 	uint16_t used, avail, flags;
 
@@ -264,16 +264,9 @@ __desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
 	used = !!(flags & VRING_DESC_F_USED(1));
 	avail = !!(flags & VRING_DESC_F_AVAIL(1));
 
-	return avail == used && used == wrap_counter;
-}
-
-static inline int
-desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
-{
-	return __desc_is_used(desc, vq->used_wrap_counter);
+	return avail == used && used == vq->used_wrap_counter;
 }
 
-
 static inline void
 vring_desc_init_packed(struct virtqueue *vq, int n)
 {
@@ -329,7 +322,6 @@ virtqueue_enable_intr_packed(struct virtqueue *vq)
 {
 	uint16_t *event_flags = &vq->ring_packed.driver_event->desc_event_flags;
 
-
 	if (vq->event_flags_shadow == RING_EVENT_FLAGS_DISABLE) {
 		virtio_wmb();
 		vq->event_flags_shadow = RING_EVENT_FLAGS_ENABLE;
-- 
2.21.0