interface: add a new cap for virtual interfaces

Type: improvement

The virtual interfaces can not process the headers at variable offsets from start of the packet. It requires some of the packet offload processing to be done in software i.e. checksums or GSO for packets with tunnel headers.
This patch introduces a new capability flag VNET_HW_IF_CAP_TX_FIXED_OFFSET to represent this behavior
in virtual interfaces.

Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>
Change-Id: I5ec58722b61e2ff52f58e38ff47d795f260bd1d5

Author: mohsinkazmi

src/plugins/af_packet/af_packet.c

@@ -629,7 +629,8 @@ af_packet_create_if (af_packet_create_if_arg_t *arg)
   u8 hw_addr[6];
   vnet_sw_interface_t *sw;
   vnet_main_t *vnm = vnet_get_main ();
-  vnet_hw_if_caps_t caps = VNET_HW_IF_CAP_INT_MODE;
+  vnet_hw_if_caps_t caps =
+    VNET_HW_IF_CAP_INT_MODE | VNET_HW_IF_CAP_TX_FIXED_OFFSET;
   uword *p;
   uword if_index;
   u8 *host_if_name_dup = 0;

src/plugins/vhost/vhost_user.c

@@ -1636,7 +1636,9 @@ vhost_user_vui_init (vnet_main_t * vnm, vhost_user_intf_t * vui,
   for (q = 0; q < vec_len (vui->vrings); q++)
     vhost_user_vring_init (vui, q);
 
-  vnet_hw_if_set_caps (vnm, vui->hw_if_index, VNET_HW_IF_CAP_INT_MODE);
+  vnet_hw_if_set_caps (vnm, vui->hw_if_index,
+		       VNET_HW_IF_CAP_INT_MODE |
+			 VNET_HW_IF_CAP_TX_FIXED_OFFSET);
   vnet_hw_interface_set_flags (vnm, vui->hw_if_index, 0);
 
   if (sw_if_index)

src/plugins/vmxnet3/vmxnet3.c

@@ -814,11 +814,12 @@ vmxnet3_create_if (vlib_main_t * vm, vmxnet3_create_if_args_t * args)
   args->sw_if_index = sw->sw_if_index;
 
   cc.mask = VNET_HW_IF_CAP_INT_MODE | VNET_HW_IF_CAP_TCP_GSO |
-	    VNET_HW_IF_CAP_TX_TCP_CKSUM | VNET_HW_IF_CAP_TX_UDP_CKSUM;
+	    VNET_HW_IF_CAP_TX_TCP_CKSUM | VNET_HW_IF_CAP_TX_UDP_CKSUM |
+	    VNET_HW_IF_CAP_TX_FIXED_OFFSET;
   if (vd->gso_enable)
     cc.val = cc.mask;
   else
-    cc.val = VNET_HW_IF_CAP_INT_MODE;
+    cc.val = VNET_HW_IF_CAP_INT_MODE | VNET_HW_IF_CAP_TX_FIXED_OFFSET;
 
   vnet_hw_if_change_caps (vnm, vd->hw_if_index, &cc);
 

src/vnet/devices/tap/tap.c

@@ -678,8 +678,9 @@ tap_create_if (vlib_main_t * vm, tap_create_if_args_t * args)
   args->rv = 0;
   hw = vnet_get_hw_interface (vnm, vif->hw_if_index);
   cc.mask = VNET_HW_IF_CAP_INT_MODE | VNET_HW_IF_CAP_TCP_GSO |
-	    VNET_HW_IF_CAP_TX_TCP_CKSUM | VNET_HW_IF_CAP_TX_UDP_CKSUM;
-  cc.val = VNET_HW_IF_CAP_INT_MODE;
+	    VNET_HW_IF_CAP_TX_TCP_CKSUM | VNET_HW_IF_CAP_TX_UDP_CKSUM |
+	    VNET_HW_IF_CAP_TX_FIXED_OFFSET;
+  cc.val = VNET_HW_IF_CAP_INT_MODE | VNET_HW_IF_CAP_TX_FIXED_OFFSET;
 
   if (args->tap_flags & TAP_FLAG_GSO)
     cc.val |= VNET_HW_IF_CAP_TCP_GSO | VNET_HW_IF_CAP_TX_TCP_CKSUM |

src/vnet/devices/virtio/pci.c

@@ -530,9 +530,9 @@ virtio_pci_offloads (vlib_main_t * vm, virtio_if_t * vif, int gso_enabled,
 	    {
 	      vif->gso_enabled = 1;
 	      vif->csum_offload_enabled = 1;
-	      cc.val = cc.mask = VNET_HW_IF_CAP_TCP_GSO |
-				 VNET_HW_IF_CAP_TX_TCP_CKSUM |
-				 VNET_HW_IF_CAP_TX_UDP_CKSUM;
+	      cc.val = cc.mask =
+		VNET_HW_IF_CAP_TCP_GSO | VNET_HW_IF_CAP_TX_TCP_CKSUM |
+		VNET_HW_IF_CAP_TX_UDP_CKSUM | VNET_HW_IF_CAP_TX_FIXED_OFFSET;
 	    }
 	}
       else if (csum_offload_enabled
@@ -546,10 +546,12 @@ virtio_pci_offloads (vlib_main_t * vm, virtio_if_t * vif, int gso_enabled,
 	    {
 	      vif->csum_offload_enabled = 1;
 	      vif->gso_enabled = 0;
-	      cc.val =
-		VNET_HW_IF_CAP_TX_TCP_CKSUM | VNET_HW_IF_CAP_TX_UDP_CKSUM;
+	      cc.val = VNET_HW_IF_CAP_TX_TCP_CKSUM |
+		       VNET_HW_IF_CAP_TX_UDP_CKSUM |
+		       VNET_HW_IF_CAP_TX_FIXED_OFFSET;
 	      cc.mask = VNET_HW_IF_CAP_TCP_GSO | VNET_HW_IF_CAP_TX_TCP_CKSUM |
-			VNET_HW_IF_CAP_TX_UDP_CKSUM;
+			VNET_HW_IF_CAP_TX_UDP_CKSUM |
+			VNET_HW_IF_CAP_TX_FIXED_OFFSET;
 	    }
 	}
       else
@@ -563,7 +565,8 @@ virtio_pci_offloads (vlib_main_t * vm, virtio_if_t * vif, int gso_enabled,
 	      vif->csum_offload_enabled = 0;
 	      vif->gso_enabled = 0;
 	      cc.val = 0;
-	      cc.mask = VNET_HW_IF_CAP_L4_TX_CKSUM | VNET_HW_IF_CAP_TCP_GSO;
+	      cc.mask = VNET_HW_IF_CAP_L4_TX_CKSUM | VNET_HW_IF_CAP_TCP_GSO |
+			VNET_HW_IF_CAP_TX_FIXED_OFFSET;
 	    }
 	}
     }

src/vnet/interface.h

@@ -565,6 +565,7 @@ typedef enum vnet_hw_interface_flags_t_
   _ (16, UDP_TNL_GSO, "udp-tnl-gso")                                          \
   _ (17, IP_TNL_GSO, "ip-tnl-gso")                                            \
   _ (18, TCP_LRO, "tcp-lro")                                                  \
+  _ (19, TX_FIXED_OFFSET, "fixed-offset") /* virtual interfaces */            \
   _ (30, INT_MODE, "int-mode")                                                \
   _ (31, MAC_FILTER, "mac-filter")