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

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

On 10/25/18 3:48 PM, Jens Freimann wrote:
> 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.

I guess oyu vcan have a union between struct vring and struct
vring_packed?

> Thanks for your review!
> 
> regards,
> Jens
>>
>> Thanks