[dpdk-dev] [PATCH v2] virtio: use zeroed memory for simple TX header

[Rich Lane <rich.lane@bigswitch.com>]

For simple TX the virtio-net header must be zeroed, but it was using memory
that had been initialized with indirect descriptor tables. This resulted in
"unsupported gso type" errors from librte_vhost.

We can use the same memory for every descriptor to save cachelines in the
vswitch.

Fixes: 6dc5de3a (virtio: use indirect ring elements)
Signed-off-by: Rich Lane <rlane@bigswitch.com>
---
v1-v2:
- Use offsetof to get address of tx_hdr

 drivers/net/virtio/virtio_rxtx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 2b88efd..ef21d8e 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -377,7 +377,7 @@ virtio_dev_vring_start(struct virtqueue *vq, int queue_type)
 				vq->vq_ring.desc[i + mid_idx].next = i;
 				vq->vq_ring.desc[i + mid_idx].addr =
 					vq->virtio_net_hdr_mem +
-						i * vq->hw->vtnet_hdr_size;
+					offsetof(struct virtio_tx_region, tx_hdr);
 				vq->vq_ring.desc[i + mid_idx].len =
 					vq->hw->vtnet_hdr_size;
 				vq->vq_ring.desc[i + mid_idx].flags =
-- 
1.9.1