virtio: use zeroed memory for simple Tx header

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 <rich.lane@bigswitch.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Acked-by: Jianfeng Tan <jianfeng.tan@intel.com>

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 2b88efd..ef21d8e 100644 (file)
--- 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 =