virtio-net: Introduce hash report feature

The feature VIRTIO_NET_F_HASH_REPORT extends the
layout of the packet and requests the device to
calculate hash on incoming packets and report it
in the packet header.

Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Link: https://lore.kernel.org/r/20200302115003.14877-4-yuri.benditovich@daynix.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

include/uapi/linux/virtio_net.h

@@ -57,6 +57,7 @@
 					 * Steering */
 #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
 
+#define VIRTIO_NET_F_HASH_REPORT  57	/* Supports hash report */
 #define VIRTIO_NET_F_RSS	  60	/* Supports RSS RX steering */
 #define VIRTIO_NET_F_RSC_EXT	  61	/* extended coalescing info */
 #define VIRTIO_NET_F_STANDBY	  62	/* Act as standby for another device
@@ -156,6 +157,23 @@ struct virtio_net_hdr_v1 {
 	__virtio16 num_buffers;	/* Number of merged rx buffers */
 };
 
+struct virtio_net_hdr_v1_hash {
+	struct virtio_net_hdr_v1 hdr;
+	__le32 hash_value;
+#define VIRTIO_NET_HASH_REPORT_NONE            0
+#define VIRTIO_NET_HASH_REPORT_IPv4            1
+#define VIRTIO_NET_HASH_REPORT_TCPv4           2
+#define VIRTIO_NET_HASH_REPORT_UDPv4           3
+#define VIRTIO_NET_HASH_REPORT_IPv6            4
+#define VIRTIO_NET_HASH_REPORT_TCPv6           5
+#define VIRTIO_NET_HASH_REPORT_UDPv6           6
+#define VIRTIO_NET_HASH_REPORT_IPv6_EX         7
+#define VIRTIO_NET_HASH_REPORT_TCPv6_EX        8
+#define VIRTIO_NET_HASH_REPORT_UDPv6_EX        9
+	__le16 hash_report;
+	__le16 padding;
+};
+
 #ifndef VIRTIO_NET_NO_LEGACY
 /* This header comes first in the scatter-gather list.
  * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated, it must
@@ -304,6 +322,24 @@ struct virtio_net_rss_config {
 
  #define VIRTIO_NET_CTRL_MQ_RSS_CONFIG          1
 
+/*
+ * The command VIRTIO_NET_CTRL_MQ_HASH_CONFIG requests the device
+ * to include in the virtio header of the packet the value of the
+ * calculated hash and the report type of hash. It also provides
+ * parameters for hash calculation. The command requires feature
+ * VIRTIO_NET_F_HASH_REPORT to be negotiated to extend the
+ * layout of virtio header as defined in virtio_net_hdr_v1_hash.
+ */
+struct virtio_net_hash_config {
+	__le32 hash_types;
+	/* for compatibility with virtio_net_rss_config */
+	__le16 reserved[4];
+	__u8 hash_key_length;
+	__u8 hash_key_data[/* hash_key_length */];
+};
+
+ #define VIRTIO_NET_CTRL_MQ_HASH_CONFIG         2
+
 /*
  * Control network offloads
  *