Re: [dpdk-dev] [PATCH v10 1/9] net/virtio: vring init for packed queues

[Tiwei Bie <tiwei.bie@intel.com>]

On Fri, Nov 02, 2018 at 10:07:41AM +0100, Jens Freimann wrote:
> Add and initialize descriptor data structures.
> 
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>
> ---
>  drivers/net/virtio/virtio_ethdev.c | 22 +++++++----
>  drivers/net/virtio/virtio_pci.h    |  7 ++++
>  drivers/net/virtio/virtio_ring.h   | 60 ++++++++++++++++++++++++++----
>  drivers/net/virtio/virtqueue.h     | 19 +++++++++-
>  4 files changed, 92 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 27088e3a6..0f5a3b80f 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -299,19 +299,21 @@ virtio_init_vring(struct virtqueue *vq)
>  
>  	PMD_INIT_FUNC_TRACE();
>  
> -	/*
> -	 * Reinitialise since virtio port might have been stopped and restarted
> -	 */

This comment is supposed to be kept in this version.

>  	memset(ring_mem, 0, vq->vq_ring_size);
> -	vring_init(vr, size, ring_mem, VIRTIO_PCI_VRING_ALIGN);
> +
>  	vq->vq_used_cons_idx = 0;
>  	vq->vq_desc_head_idx = 0;
>  	vq->vq_avail_idx = 0;
>  	vq->vq_desc_tail_idx = (uint16_t)(vq->vq_nentries - 1);
>  	vq->vq_free_cnt = vq->vq_nentries;
>  	memset(vq->vq_descx, 0, sizeof(struct vq_desc_extra) * vq->vq_nentries);
> -
> -	vring_desc_init(vr->desc, size);
> +	if (vtpci_packed_queue(vq->hw)) {
> +		vring_init_packed(&vq->ring_packed, ring_mem, VIRTIO_PCI_VRING_ALIGN, size);
> +		vring_desc_init_packed(vq, size);
> +	} else {
> +		vring_init_split(vr, ring_mem, VIRTIO_PCI_VRING_ALIGN, size);
> +		vring_desc_init_split(vr->desc, size);
> +	}
>  
>  	/*
>  	 * Disable device(host) interrupting guest
[...]
> diff --git a/drivers/net/virtio/virtio_ring.h b/drivers/net/virtio/virtio_ring.h
> index 9e3c2a015..69ec84d1e 100644
> --- a/drivers/net/virtio/virtio_ring.h
> +++ b/drivers/net/virtio/virtio_ring.h
> @@ -54,9 +54,35 @@ struct vring_used {
>  	struct vring_used_elem ring[0];
>  };
>  
> +/* For support of packed virtqueues in Virtio 1.1 the format of descriptors
> + * looks like this.
> + */
> +struct vring_desc_packed {

Please change the name to vring_packed_desc to make the name
consistent with the name in vhost code.

> +	uint64_t addr;
> +	uint32_t len;
> +	uint16_t index;

The `index` is supposed to be changed to `id` in this version.

> +	uint16_t flags;
> +} __attribute__ ((aligned(16)));

When defining the structure for vring desc, I think the
__attribute__ ((aligned(16))) isn't needed.

> +
> +#define RING_EVENT_FLAGS_ENABLE 0x0
> +#define RING_EVENT_FLAGS_DISABLE 0x1
> +#define RING_EVENT_FLAGS_DESC 0x2

An empty line is supposed to be added here in this version.

> +struct vring_packed_desc_event {
> +	uint16_t desc_event_off_wrap;
> +	uint16_t desc_event_flags;
> +};
> +
> +struct vring_packed {
> +	unsigned int num;
> +	struct vring_desc_packed *desc_packed;
> +	struct vring_packed_desc_event *driver_event;
> +	struct vring_packed_desc_event *device_event;
> +
> +};
> +
>  struct vring {
>  	unsigned int num;
> -	struct vring_desc  *desc;
> +	struct vring_desc *desc;

Above change is unnecessary.

>  	struct vring_avail *avail;
>  	struct vring_used  *used;
>  };
> @@ -95,10 +121,18 @@ struct vring {
>  #define vring_avail_event(vr) (*(uint16_t *)&(vr)->used->ring[(vr)->num])
>  
>  static inline size_t
> -vring_size(unsigned int num, unsigned long align)
> +vring_size(struct virtio_hw *hw, unsigned int num, unsigned long align)
>  {
>  	size_t size;
>  
> +	if (vtpci_packed_queue(hw)) {
> +		size = num * sizeof(struct vring_desc_packed);
> +		size += sizeof(struct vring_packed_desc_event);
> +		size = RTE_ALIGN_CEIL(size, align);
> +		size += sizeof(struct vring_packed_desc_event);
> +		return size;
> +	}
> +
>  	size = num * sizeof(struct vring_desc);
>  	size += sizeof(struct vring_avail) + (num * sizeof(uint16_t));
>  	size = RTE_ALIGN_CEIL(size, align);
> @@ -106,17 +140,29 @@ vring_size(unsigned int num, unsigned long align)
>  		(num * sizeof(struct vring_used_elem));
>  	return size;
>  }
> -

Why above empty line is removed?

>  static inline void
> -vring_init(struct vring *vr, unsigned int num, uint8_t *p,
> -	unsigned long align)
> +vring_init_split(struct vring *vr, uint8_t *p, unsigned long align,
> +		 unsigned int num)

Above change to the order of the params is unnecessary.

>  {
>  	vr->num = num;
>  	vr->desc = (struct vring_desc *) p;
>  	vr->avail = (struct vring_avail *) (p +
> -		num * sizeof(struct vring_desc));
> +			vr->num * sizeof(struct vring_desc));

Above change is unnecessary.

>  	vr->used = (void *)
> -		RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num]), align);
> +		RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[vr->num]), align);

Above change is unnecessary.

> +}
> +
> +static inline void
> +vring_init_packed(struct vring_packed *vr, uint8_t *p, unsigned long align,
> +		 unsigned int num)
> +{
> +	vr->num = num;
> +	vr->desc_packed = (struct vring_desc_packed *)p;
> +	vr->driver_event = (struct vring_packed_desc_event *)(p +
> +			vr->num * sizeof(struct vring_desc_packed));
> +	vr->device_event = (struct vring_packed_desc_event *)
> +		RTE_ALIGN_CEIL((uintptr_t)(vr->driver_event +
> +				sizeof(struct vring_packed_desc_event)), align);
>  }
>  
>  /*
> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
> index 26518ed98..90bff7e38 100644
> --- a/drivers/net/virtio/virtqueue.h
> +++ b/drivers/net/virtio/virtqueue.h
> @@ -161,11 +161,16 @@ struct virtio_pmd_ctrl {
>  struct vq_desc_extra {
>  	void *cookie;
>  	uint16_t ndescs;
> +	uint16_t next;
>  };
>  
>  struct virtqueue {
>  	struct virtio_hw  *hw; /**< virtio_hw structure pointer. */
>  	struct vring vq_ring;  /**< vring keeping desc, used and avail */
> +	struct vring_packed ring_packed;  /**< vring keeping desc, used and avail */

The comment should be updated for packed ring.

> +	bool avail_wrap_counter;
> +	bool used_wrap_counter;
> +
>  	/**
>  	 * Last consumed descriptor in the used table,
>  	 * trails vq_ring.used->idx.
> @@ -245,9 +250,21 @@ struct virtio_tx_region {
>  			   __attribute__((__aligned__(16)));
>  };
>  
> +static inline void
> +vring_desc_init_packed(struct virtqueue *vq, int n)
> +{
> +	int i;
> +	for (i = 0; i < n - 1; i++) {
> +		vq->ring_packed.desc_packed[i].index = i;
> +		vq->vq_descx[i].next = i + 1;
> +	}
> +	vq->ring_packed.desc_packed[i].index = i;
> +	vq->vq_descx[i].next = VQ_RING_DESC_CHAIN_END;
> +}
> +
>  /* Chain all the descriptors in the ring with an END */
>  static inline void
> -vring_desc_init(struct vring_desc *dp, uint16_t n)
> +vring_desc_init_split(struct vring_desc *dp, uint16_t n)
>  {
>  	uint16_t i;
>  
> -- 
> 2.17.1
>