[dpdk-stable] [PATCH] vhost: fix vhost interrupt support

[Tiwei Bie]

When VIRTIO_RING_F_EVENT_IDX is negotiated, we need to
update the avail event to enable the notification.

Fixes: 3f8ff12821e4 ("vhost: support interrupt mode")
Cc: stable at dpdk.org

Signed-off-by: Tiwei Bie <tiwei.bie at intel.com>
---
 lib/librte_vhost/Makefile |  1 +
 lib/librte_vhost/vhost.c  | 18 ++++++++++++------
 lib/librte_vhost/vhost.h  |  2 ++
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile
index de431fbb7..531cf4832 100644
--- a/lib/librte_vhost/Makefile
+++ b/lib/librte_vhost/Makefile
@@ -13,6 +13,7 @@ LIBABIVER := 4
 CFLAGS += -DALLOW_EXPERIMENTAL_API
 CFLAGS += $(WERROR_FLAGS) -I$(SRCDIR) -O3 -D_FILE_OFFSET_BITS=64
 CFLAGS += -I vhost_user
+CFLAGS += -fno-strict-aliasing
 LDLIBS += -lpthread
 
 ifeq ($(CONFIG_RTE_LIBRTE_VHOST_NUMA),y)
diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index 3c9be10a0..88b1781d5 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -646,12 +646,18 @@ rte_vhost_avail_entries(int vid, uint16_t queue_id)
 }
 
 static inline void
-vhost_enable_notify_split(struct vhost_virtqueue *vq, int enable)
+vhost_enable_notify_split(struct virtio_net *dev,
+		struct vhost_virtqueue *vq, int enable)
 {
-	if (enable)
-		vq->used->flags &= ~VRING_USED_F_NO_NOTIFY;
-	else
-		vq->used->flags |= VRING_USED_F_NO_NOTIFY;
+	if (!(dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX))) {
+		if (enable)
+			vq->used->flags &= ~VRING_USED_F_NO_NOTIFY;
+		else
+			vq->used->flags |= VRING_USED_F_NO_NOTIFY;
+	} else {
+		if (enable)
+			vhost_avail_event(vq) = vq->last_avail_idx;
+	}
 }
 
 static inline void
@@ -689,7 +695,7 @@ rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int enable)
 	if (vq_is_packed(dev))
 		vhost_enable_notify_packed(dev, vq, enable);
 	else
-		vhost_enable_notify_split(vq, enable);
+		vhost_enable_notify_split(dev, vq, enable);
 
 	return 0;
 }
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 760a09c0d..25ffd7614 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -648,6 +648,8 @@ vhost_iova_to_vva(struct virtio_net *dev, struct vhost_virtqueue *vq,
 	return __vhost_iova_to_vva(dev, vq, iova, len, perm);
 }
 
+#define vhost_avail_event(vr) \
+	(*(volatile uint16_t*)&(vr)->used->ring[(vr)->size])
 #define vhost_used_event(vr) \
 	(*(volatile uint16_t*)&(vr)->avail->ring[(vr)->size])
 
-- 
2.18.0