[dpdk-dev] [PATCH 1/3] vhost: Fix return value of GET_VRING_BASE message
Yuanhan Liu
yuanhan.liu at linux.intel.com
Thu Oct 8 07:54:52 CEST 2015
On Wed, Aug 19, 2015 at 06:51:07PM +0900, Tetsuya Mukawa wrote:
> When vhost-user frontend sends GET_VRING_BASE, last used index of vring
> should be returned. In DPDK vhost library, 'last_used_idx' represents it.
> But the value can be over max index value.
That's true, and I guess it's a design. If you look at the linux
kernel vhost code, you will find that there is no such wrap, either.
> To return correct value to
> vhost frontend, it's needed to be masked.
So, it's the frontend job to get the right value, by wrapping it
within vring size.
--yliu
>
> Signed-off-by: Tetsuya Mukawa <mukawa at igel.co.jp>
> ---
> lib/librte_vhost/virtio-net.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
> index b520ec5..144f301 100644
> --- a/lib/librte_vhost/virtio-net.c
> +++ b/lib/librte_vhost/virtio-net.c
> @@ -661,7 +661,8 @@ get_vring_base(struct vhost_device_ctx ctx, uint32_t index,
>
> state->index = index;
> /* State->index refers to the queue index. The txq is 1, rxq is 0. */
> - state->num = dev->virtqueue[state->index]->last_used_idx;
> + state->num = dev->virtqueue[state->index]->last_used_idx
> + & (dev->virtqueue[state->index]->size - 1);
>
> return 0;
> }
> --
> 2.1.4
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