Re: [dpdk-dev] [PATCH v12 03/10] net/virtio: add packed virtqueue helpers

[Jens Freimann <jfreimann@redhat.com>]

On Thu, Dec 13, 2018 at 05:09:03PM +0100, Maxime Coquelin wrote:
>
>
>On 12/13/18 1:34 PM, Jens Freimann wrote:
>>Add helper functions to set/clear and check descriptor flags.
>>
>>Signed-off-by: Jens Freimann <jfreimann@redhat.com>
>>---
>>  drivers/net/virtio/virtqueue.h | 72 +++++++++++++++++++++++++++++++++-
>>  1 file changed, 70 insertions(+), 2 deletions(-)
>>
>>diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
>>index 1401a9844..b7a5a5963 100644
>>--- a/drivers/net/virtio/virtqueue.h
>>+++ b/drivers/net/virtio/virtqueue.h
>>@@ -250,6 +250,32 @@ struct virtio_tx_region {
>>  			   __attribute__((__aligned__(16)));
>>  };
>>+static inline void
>>+_set_desc_avail(struct vring_packed_desc *desc, int wrap_counter)
>>+{
>>+	desc->flags |= VRING_DESC_F_AVAIL(wrap_counter) |
>>+		       VRING_DESC_F_USED(!wrap_counter);
>>+}
>>+
>>+static inline void
>>+set_desc_avail(struct virtqueue *vq, struct vring_packed_desc *desc)
>>+{
>>+	_set_desc_avail(desc, vq->avail_wrap_counter);
>>+}
>>+
>>+static inline int
>>+desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
>>+{
>>+	uint16_t used, avail, flags;
>>+
>>+	flags = desc->flags;
>>+	used = !!(flags & VRING_DESC_F_USED(1));
>>+	avail = !!(flags & VRING_DESC_F_AVAIL(1));
>>+
>>+	return avail == used && used == vq->used_wrap_counter;
>>+}
>>+
>>+
>>  static inline void
>>  vring_desc_init_packed(struct virtqueue *vq, int n)
>>  {
>>@@ -273,22 +299,64 @@ vring_desc_init_split(struct vring_desc *dp, uint16_t n)
>>  	dp[i].next = VQ_RING_DESC_CHAIN_END;
>>  }
>>+/**
>>+ * Tell the backend not to interrupt us.
>>+ */
>>+static inline void
>>+virtqueue_disable_intr_packed(struct virtqueue *vq)
>>+{
>>+	uint16_t *event_flags = &vq->ring_packed.driver_event->desc_event_flags;
>>+
>>+	if (*event_flags != RING_EVENT_FLAGS_DISABLE) {
>>+		*event_flags = RING_EVENT_FLAGS_DISABLE;
>>+	}
>>+}
>>+
>>+
>>  /**
>>   * Tell the backend not to interrupt us.
>>   */
>>  static inline void
>>  virtqueue_disable_intr(struct virtqueue *vq)
>>  {
>>-	vq->vq_ring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
>>+	if (vtpci_packed_queue(vq->hw))
>>+		virtqueue_disable_intr_packed(vq);
>>+	else
>>+		vq->vq_ring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
>>+}
>>+
>>+/**
>>+ * Tell the backend to interrupt us.
>>+ */
>>+static inline void
>>+virtqueue_enable_intr_packed(struct virtqueue *vq)
>>+{
>>+	uint16_t *off_wrap = &vq->ring_packed.driver_event->desc_event_off_wrap;
>>+	uint16_t *event_flags = &vq->ring_packed.driver_event->desc_event_flags;
>>+
>>+	*off_wrap = vq->vq_used_cons_idx |
>>+		((uint16_t)(vq->used_wrap_counter << 15));
>>+
>>+	if (vq->event_flags_shadow == RING_EVENT_FLAGS_DISABLE) {
>>+		virtio_wmb();
>>+		vq->event_flags_shadow =
>>+			vtpci_with_feature(vq->hw, VIRTIO_RING_F_EVENT_IDX) ?
>>+				RING_EVENT_FLAGS_DESC : RING_EVENT_FLAGS_ENABLE;
>>+		*event_flags = vq->event_flags_shadow;
>>+	}
>>  }
>>+
>>  /**
>>   * Tell the backend to interrupt us.
>>   */
>>  static inline void
>>  virtqueue_enable_intr(struct virtqueue *vq)
>>  {
>>-	vq->vq_ring.avail->flags &= (~VRING_AVAIL_F_NO_INTERRUPT);
>>+	if (vtpci_packed_queue(vq->hw))
>>+		virtqueue_enable_intr_packed(vq);
>>+	else
>>+		vq->vq_ring.avail->flags &= (~VRING_AVAIL_F_NO_INTERRUPT);
>>  }
>>  /**
>>
>
>IIRC, I asked in previous series to have dedicated functions for split
>ring. It does not have any functional change, but it would be clearer
>IMHO.
>
>I'm ok that it is done after the series is applied though.

Sorry, I missed this. We'll need another respin anyway so I'll fix it.

regards,
Jens