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

[Jens Freimann <jfreimann@redhat.com>]

On Thu, Oct 25, 2018 at 05:21:15PM +0800, Tiwei Bie wrote:
>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?

by mistake, I'll put them back in next version. 
>
>>  	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?

Yes, I missed this here. I'll fix it. 
>
>> +	} 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/

ok
>
>> +	uint16_t flags;
>> +} __attribute__ ((aligned(16)));
>
>We don't need the "__attribute__ ((aligned(16)))" in descriptor
>structure's definition.

Someone requested this in an earlier round of reviews, but I'll
check again.

>
>> +
>> +#define RING_EVENT_FLAGS_ENABLE 0x0
>> +#define RING_EVENT_FLAGS_DISABLE 0x1
>> +#define RING_EVENT_FLAGS_DESC 0x2
>
>Please add an empty line here.

ok

>
>> +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.

I think it was requested to have it as a union before, but I can do
it.

Thanks for your review!

regards,
Jens 
>
>Thanks