net/mlx5: add ConnectX6-DX device ID

[dpdk.git] / drivers / net / virtio / virtqueue.h

diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index b728ff8..8d7f197 100644 (file)
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -54,6 +54,32 @@ virtio_wmb(uint8_t weak_barriers)
                rte_cio_wmb();
 }
 
+static inline uint16_t
+virtqueue_fetch_flags_packed(struct vring_packed_desc *dp,
+                             uint8_t weak_barriers)
+{
+       uint16_t flags;
+
+       if (weak_barriers) {
+/* x86 prefers to using rte_smp_rmb over __atomic_load_n as it reports
+ * a better perf(~1.5%), which comes from the saved branch by the compiler.
+ * The if and else branch are identical with the smp and cio barriers both
+ * defined as compiler barriers on x86.
+ */
+#ifdef RTE_ARCH_X86_64
+               flags = dp->flags;
+               rte_smp_rmb();
+#else
+               flags = __atomic_load_n(&dp->flags, __ATOMIC_ACQUIRE);
+#endif
+       } else {
+               flags = dp->flags;
+               rte_cio_rmb();
+       }
+
+       return flags;
+}
+
 static inline void
 virtqueue_store_flags_packed(struct vring_packed_desc *dp,
                              uint16_t flags, uint8_t weak_barriers)
@@ -307,7 +333,7 @@ desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
 {
        uint16_t used, avail, flags;
 
-       flags = desc->flags;
+       flags = virtqueue_fetch_flags_packed(desc, vq->hw->weak_barriers);
        used = !!(flags & VRING_PACKED_DESC_F_USED);
        avail = !!(flags & VRING_PACKED_DESC_F_AVAIL);