[dpdk-dev] [RFC 3/3] net/virtio: add election for packed vector Rx NEON path

[Joyce Kong]

Add NEON vectorized path selection logic. Default setting comes from
vectorized devarg, then checks each criteria.

Packed ring vectorized neon path need:
    NEON is supported by compiler and host
    VERSION_1 and IN_ORDER features are negotiated
    mergeable feature is not negotiated
    LRO offloading is disabled

Signed-off-by: Joyce Kong <joyce.kong at arm.com>
---
 doc/guides/nics/virtio.rst              |  4 ++--
 drivers/net/virtio/virtio_ethdev.c      | 19 +++++++++++++++----
 drivers/net/virtio/virtio_user_ethdev.c |  2 ++
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/doc/guides/nics/virtio.rst b/doc/guides/nics/virtio.rst
index 0daf25b22..fe9586699 100644
--- a/doc/guides/nics/virtio.rst
+++ b/doc/guides/nics/virtio.rst
@@ -483,8 +483,8 @@ according to below configuration:
 #. Packed virtqueue in-order non-mergeable path: If in-order feature is negotiated and
    Rx mergeable is not negotiated, this path will be selected.
 #. Packed virtqueue vectorized Rx path: If building and running environment support
-   AVX512 && in-order feature is negotiated && Rx mergeable is not negotiated &&
-   TCP_LRO Rx offloading is disabled && vectorized option enabled,
+   (AVX512 || ARCH_ARM || ARCH_ARM64) && in-order feature is negotiated && Rx mergeable
+   is not negotiated && TCP_LRO Rx offloading is disabled && vectorized option enabled,
    this path will be selected.
 #. Packed virtqueue vectorized Tx path: If building and running environment support
    AVX512 && in-order feature is negotiated && vectorized option enabled,
diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index dc0093bdf..b36ea98cf 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1958,12 +1958,14 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
 		if (!vtpci_packed_queue(hw)) {
 			hw->use_vec_rx = 1;
 		} else {
-#if !defined(CC_AVX512_SUPPORT)
-			PMD_DRV_LOG(INFO,
-				"building environment do not support packed ring vectorized");
-#else
+#if defined(CC_AVX512_SUPPORT)
 			hw->use_vec_rx = 1;
 			hw->use_vec_tx = 1;
+#elif defined(RTE_ARCH_ARM) || defined(RTE_ARCH_ARM64)
+			hw->use_vec_rx = 1;
+#else
+			PMD_DRV_LOG(INFO,
+				"building environment do not support packed ring vectorized");
 #endif
 		}
 	}
@@ -2311,6 +2313,15 @@ virtio_dev_configure(struct rte_eth_dev *dev)
 			hw->use_vec_rx = 0;
 			hw->use_vec_tx = 0;
 		}
+#elif defined(RTE_ARCH_ARM) || defined(RTE_ARCH_ARM64)
+		if (hw->use_vec_rx &&
+		    (!rte_cpu_get_flag_enabled(RTE_CPUFLAG_NEON) ||
+		     !vtpci_with_feature(hw, VIRTIO_F_IN_ORDER) ||
+		     !vtpci_with_feature(hw, VIRTIO_F_VERSION_1))) {
+			PMD_DRV_LOG(INFO,
+				"disabled packed ring vectorized path for requirements not met");
+			hw->use_vec_rx = 0;
+		}
 #else
 		hw->use_vec_rx = 0;
 		hw->use_vec_tx = 0;
diff --git a/drivers/net/virtio/virtio_user_ethdev.c b/drivers/net/virtio/virtio_user_ethdev.c
index 6003f6d50..1cfeb388f 100644
--- a/drivers/net/virtio/virtio_user_ethdev.c
+++ b/drivers/net/virtio/virtio_user_ethdev.c
@@ -766,6 +766,8 @@ virtio_user_pmd_probe(struct rte_vdev_device *dev)
 #if defined(CC_AVX512_SUPPORT)
 			hw->use_vec_rx = 1;
 			hw->use_vec_tx = 1;
+#elif defined(RTE_ARCH_ARM) || defined(RTE_ARCH_ARM64)
+			hw->use_vec_rx = 1;
 #else
 			PMD_INIT_LOG(INFO,
 				"building environment do not support packed ring vectorized");
-- 
2.28.0