Re: [PATCH v9 1/8] net/virtio: vring init for packed queues

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

On Wed, Oct 24, 2018 at 04:32:29PM +0200, Jens Freimann wrote:
> Add and initialize descriptor data structures.
> 
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>
> ---
>  drivers/net/virtio/virtio_ethdev.c | 18 ++++----
>  drivers/net/virtio/virtio_pci.h    |  7 +++
>  drivers/net/virtio/virtio_ring.h   | 74 ++++++++++++++++++++++++++----
>  drivers/net/virtio/virtqueue.h     | 15 +++++-
>  4 files changed, 95 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 730c41707..6130aef16 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
> -	 */

Why above comments are removed?

>  	memset(ring_mem, 0, vq->vq_ring_size);
> -	vring_init(vr, size, ring_mem, VIRTIO_PCI_VRING_ALIGN);
> +	vring_init(vq->hw, 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)) {
> +		if (!vtpci_with_feature(vq->hw, VIRTIO_F_IN_ORDER))
> +			vring_desc_init_packed(vq, size);

Don't we need to initialize descs in IN-ORDER case?

> +	} else {
> +		vring_desc_init_split(vr->desc, size);
> +	}
>  
>  	/*
>  	 * Disable device(host) interrupting guest
> @@ -386,7 +388,7 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t vtpci_queue_idx)
>  	/*
>  	 * Reserve a memzone for vring elements
>  	 */
> -	size = vring_size(vq_size, VIRTIO_PCI_VRING_ALIGN);
> +	size = vring_size(hw, vq_size, VIRTIO_PCI_VRING_ALIGN);
>  	vq->vq_ring_size = RTE_ALIGN_CEIL(size, VIRTIO_PCI_VRING_ALIGN);
>  	PMD_INIT_LOG(DEBUG, "vring_size: %d, rounded_vring_size: %d",
>  		     size, vq->vq_ring_size);
> @@ -489,7 +491,7 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t vtpci_queue_idx)
>  		for (i = 0; i < vq_size; i++) {
>  			struct vring_desc *start_dp = txr[i].tx_indir;
>  
> -			vring_desc_init(start_dp, RTE_DIM(txr[i].tx_indir));
> +			vring_desc_init_split(start_dp, RTE_DIM(txr[i].tx_indir));
>  
>  			/* first indirect descriptor is always the tx header */
>  			start_dp->addr = txvq->virtio_net_hdr_mem
> diff --git a/drivers/net/virtio/virtio_pci.h b/drivers/net/virtio/virtio_pci.h
> index 58fdd3d45..c487d2be0 100644
> --- a/drivers/net/virtio/virtio_pci.h
> +++ b/drivers/net/virtio/virtio_pci.h
> @@ -113,6 +113,7 @@ struct virtnet_ctl;
>  
>  #define VIRTIO_F_VERSION_1		32
>  #define VIRTIO_F_IOMMU_PLATFORM	33
> +#define VIRTIO_F_RING_PACKED		34
>  
>  /*
>   * Some VirtIO feature bits (currently bits 28 through 31) are
> @@ -314,6 +315,12 @@ vtpci_with_feature(struct virtio_hw *hw, uint64_t bit)
>  	return (hw->guest_features & (1ULL << bit)) != 0;
>  }
>  
> +static inline int
> +vtpci_packed_queue(struct virtio_hw *hw)
> +{
> +	return vtpci_with_feature(hw, VIRTIO_F_RING_PACKED);
> +}
> +
>  /*
>   * Function declaration from virtio_pci.c
>   */
> diff --git a/drivers/net/virtio/virtio_ring.h b/drivers/net/virtio/virtio_ring.h
> index 9e3c2a015..e65da100b 100644
> --- a/drivers/net/virtio/virtio_ring.h
> +++ b/drivers/net/virtio/virtio_ring.h
> @@ -54,11 +54,38 @@ 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 {
> +	uint64_t addr;
> +	uint32_t len;
> +	uint16_t index;

s/index/id/

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

We don't need the "__attribute__ ((aligned(16)))" in descriptor
structure's definition.

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

Please add an empty line here.

> +struct vring_packed_desc_event {
> +	uint16_t desc_event_off_wrap;
> +	uint16_t desc_event_flags;
> +};
> +
>  struct vring {
>  	unsigned int num;
> -	struct vring_desc  *desc;
> -	struct vring_avail *avail;
> -	struct vring_used  *used;
> +	union {
> +		struct vring_desc_packed *desc_packed;
> +		struct vring_desc *desc;
> +	};
> +	union {
> +		struct vring_avail *avail;
> +		struct vring_packed_desc_event *driver_event;
> +	};
> +	union {
> +		struct vring_used  *used;
> +		struct vring_packed_desc_event *device_event;
> +	};
>  };
>  

We should define a new `vring` structure for packed ring.

Thanks