net/virtio: add packed virtqueue helpers

Add helper functions to set/clear and check descriptor flags.

Signed-off-by: Jens Freimann <jfreimann@redhat.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/drivers/net/virtio/virtio_pci.h b/drivers/net/virtio/virtio_pci.h
index 4c975a5..b22b62d 100644 (file)
--- a/drivers/net/virtio/virtio_pci.h
+++ b/drivers/net/virtio/virtio_pci.h
@@ -315,6 +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/virtqueue.h b/drivers/net/virtio/virtqueue.h
index d4e0858..b69013d 100644 (file)
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -251,6 +251,31 @@ struct virtio_tx_region {
                           __attribute__((__aligned__(16)));
 };
 
+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)
+{
+       int i;
+       for (i = 0; i < n - 1; i++) {
+               vq->ring_packed.desc_packed[i].id = i;
+               vq->vq_descx[i].next = i + 1;
+       }
+       vq->ring_packed.desc_packed[i].id = 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)
@@ -262,13 +287,53 @@ vring_desc_init(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;
+
+       *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. Implementation for packed virtqueues.
+ */
+static inline void
+virtqueue_enable_intr_packed(struct virtqueue *vq)
+{
+       uint16_t *event_flags = &vq->ring_packed.driver_event->desc_event_flags;
+
+
+       if (vq->event_flags_shadow == RING_EVENT_FLAGS_DISABLE) {
+               virtio_wmb();
+               vq->event_flags_shadow = RING_EVENT_FLAGS_ENABLE;
+               *event_flags = vq->event_flags_shadow;
+       }
+}
+
+/**
+ * Tell the backend to interrupt. Implementation for split virtqueues.
+ */
+static inline void
+virtqueue_enable_intr_split(struct virtqueue *vq)
+{
+       vq->vq_ring.avail->flags &= (~VRING_AVAIL_F_NO_INTERRUPT);
 }
 
 /**
@@ -277,7 +342,10 @@ virtqueue_disable_intr(struct virtqueue *vq)
 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
+               virtqueue_enable_intr_split(vq);
 }
 
 /**