Re: [dpdk-dev] [PATCH] virtio-user: ctrl vq support for packed

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Jens,

On 1/9/19 5:59 PM, Jens Freimann wrote:
> Add support to virtio-user for control virtqueues
> and reverts commit "5e4e7a752 net/virtio-user: fail if
> cq used with packed vq".

I would prefer you send two patches:
1. add ctrl vq support
2. revert 5e4e7a752


> 
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>
> ---
>   .../net/virtio/virtio_user/virtio_user_dev.c  | 111 ++++++++++++++++--
>   .../net/virtio/virtio_user/virtio_user_dev.h  |   8 +-
>   drivers/net/virtio/virtio_user_ethdev.c       |  49 +++++++-
>   3 files changed, 151 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> index b9044faff..95f66d5b4 100644
> --- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
> +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> @@ -43,15 +43,26 @@ virtio_user_kick_queue(struct virtio_user_dev *dev, uint32_t queue_sel)
>   	struct vhost_vring_file file;
>   	struct vhost_vring_state state;
>   	struct vring *vring = &dev->vrings[queue_sel];
> +	struct vring_packed *pq_vring = &dev->packed_vrings[queue_sel];
>   	struct vhost_vring_addr addr = {
>   		.index = queue_sel,
> -		.desc_user_addr = (uint64_t)(uintptr_t)vring->desc,
> -		.avail_user_addr = (uint64_t)(uintptr_t)vring->avail,
> -		.used_user_addr = (uint64_t)(uintptr_t)vring->used,
>   		.log_guest_addr = 0,
>   		.flags = 0, /* disable log */
>   	};
>   
> +	if (dev->features & (1ULL << VIRTIO_F_RING_PACKED)) {
> +		addr.desc_user_addr =
> +			(uint64_t)(uintptr_t)pq_vring->desc_packed;
> +		addr.avail_user_addr =
> +			(uint64_t)(uintptr_t)pq_vring->driver_event;
> +		addr.used_user_addr =
> +			(uint64_t)(uintptr_t)pq_vring->device_event;
> +	} else {
> +		addr.desc_user_addr = (uint64_t)(uintptr_t)vring->desc;
> +		addr.avail_user_addr = (uint64_t)(uintptr_t)vring->avail;
> +		addr.used_user_addr = (uint64_t)(uintptr_t)vring->used;
> +	}
> +
>   	state.index = queue_sel;
>   	state.num = vring->num;
>   	dev->ops->send_request(dev, VHOST_USER_SET_VRING_NUM, &state);
> @@ -467,15 +478,10 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
>   	if (!in_order)
>   		dev->unsupported_features |= (1ull << VIRTIO_F_IN_ORDER);
>   
> -	if (packed_vq) {
> -		if (cq) {
> -			PMD_INIT_LOG(ERR, "control vq not supported yet with "
> -					  "packed virtqueues\n");
> -			return -1;
> -		}
> -	} else {
> -		dev->unsupported_features |= (1ull << VIRTIO_F_RING_PACKED);
> -	}
> +	if (packed_vq)
> +		dev->device_features |= (1ull << VIRTIO_F_RING_PACKED);
> +	else
> +		dev->device_features &= ~(1ull << VIRTIO_F_RING_PACKED);

Shouldn't you set VIRTIO_F_RING_PACKED bit in unsupported features?

>   
>   	if (dev->mac_specified)
>   		dev->frontend_features |= (1ull << VIRTIO_NET_F_MAC);
> @@ -620,6 +626,87 @@ virtio_user_handle_ctrl_msg(struct virtio_user_dev *dev, struct vring *vring,
>   	return n_descs;
>   }
>   
> +static inline int
> +desc_is_avail(struct vring_packed_desc *desc, bool wrap_counter)
> +{
> +	return wrap_counter == !!(desc->flags & VRING_DESC_F_AVAIL(1)) &&
> +		wrap_counter != !!(desc->flags & VRING_DESC_F_USED(1));
> +}
> +
> +static uint32_t
> +virtio_user_handle_ctrl_msg_pq(struct virtio_user_dev *dev,
> +			    struct vring_packed *vring,
> +			    uint16_t idx_hdr)
> +{
> +	struct virtio_net_ctrl_hdr *hdr;
> +	virtio_net_ctrl_ack status = ~0;
> +	uint16_t i, idx_data, idx_status;
> +	uint32_t n_descs = 0;
> +
> +	/* locate desc for header, data, and status */
> +	idx_data = idx_hdr + 1;
> +	n_descs++;
> +
> +	i = idx_data;
> +	while (vring->desc_packed[i].flags & VRING_DESC_F_NEXT) {
> +		i++;

Why not incrementing idx_status directly?

> +		n_descs++;
> +	}
> +
> +	/* locate desc for status */
> +	idx_status = i;
> +	n_descs++;

I think it would be clearer to initialize n_decsc to 1, as it could
correspond to the header (and add a comment about it).

> +
> +	hdr = (void *)(uintptr_t)vring->desc_packed[idx_hdr].addr;
> +	if (hdr->class == VIRTIO_NET_CTRL_MQ &&
> +	    hdr->cmd == VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET) {
> +		uint16_t queues;
> +
> +		queues = *(uint16_t *)(uintptr_t)
> +				vring->desc_packed[idx_data].addr;
> +		status = virtio_user_handle_mq(dev, queues);
> +	}
> +
> +	/* Update status */
> +	*(virtio_net_ctrl_ack *)(uintptr_t)
> +		vring->desc_packed[idx_status].addr = status;
> +
> +	return n_descs;
> +}
> +
> +void
> +virtio_user_handle_cq_packed(struct virtio_user_dev *dev, uint16_t queue_idx,
> +			     struct virtqueue *vq)
> +{
> +	struct vring_packed *vring = &dev->packed_vrings[queue_idx];
> +	uint16_t id, n_descs;
> +	int16_t n;
> +	bool wrap_counter = vq->used_wrap_counter;
> +
> +	while (desc_is_avail(&vring->desc_packed[vq->vq_used_cons_idx],
> +			     vq->avail_wrap_counter)) {
> +		id = vring->desc_packed[vq->vq_used_cons_idx].id;
> +
> +		n_descs = virtio_user_handle_ctrl_msg_pq(dev, vring, id);
> +
> +		vring->desc_packed[vq->vq_used_cons_idx].len = n_descs;
> +		vring->desc_packed[vq->vq_used_cons_idx].id =
> +			vq->vq_used_cons_idx;
> +		n = vq->vq_used_cons_idx + n_descs - 1;

I think it is broken as it needs to handle wrapping.

> +		while (n >= vq->vq_used_cons_idx) {
> +			vring->desc_packed[n].flags |=
> +				VRING_DESC_F_AVAIL(wrap_counter) |
> +				VRING_DESC_F_USED(wrap_counter);
> +			n--;
> +		}
> +		vq->vq_used_cons_idx += n_descs;
> +		if (vq->vq_used_cons_idx >= dev->queue_size) {
> +			vq->vq_used_cons_idx -= dev->queue_size;
> +			vq->used_wrap_counter ^= 1;
> +		}
> +	}
> +}
> +