[intelxl] Use VLAN tag in receive descriptor if present

The physical function driver does not allow the virtual function to
request that VLAN tags are left unstripped.  Extract and use the VLAN
tag from the receive descriptor if present.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/intelxl.c

 #include <ipxe/netdevice.h>
 #include <ipxe/ethernet.h>
 #include <ipxe/if_ether.h>
+#include <ipxe/vlan.h>
 #include <ipxe/iobuf.h>
 #include <ipxe/malloc.h>
 #include <ipxe/pci.h>
 	struct intelxl_rx_writeback_descriptor *rx_wb;
 	struct io_buffer *iobuf;
 	unsigned int rx_idx;
+	unsigned int tag;
 	size_t len;
 
 	/* Check for received packets */
 		len = INTELXL_RX_WB_LEN ( le32_to_cpu ( rx_wb->len ) );
 		iob_put ( iobuf, len );
 
+		/* Find VLAN device, if applicable */
+		if ( rx_wb->flags & cpu_to_le32 ( INTELXL_RX_WB_FL_VLAN ) ) {
+			tag = VLAN_TAG ( le16_to_cpu ( rx_wb->vlan ) );
+		} else {
+			tag = 0;
+		}
+
 		/* Hand off to network stack */
 		if ( rx_wb->flags & cpu_to_le32 ( INTELXL_RX_WB_FL_RXE ) ) {
 			DBGC ( intelxl, "INTELXL %p RX %d error (length %zd, "
 			       "flags %08x)\n", intelxl, rx_idx, len,
 			       le32_to_cpu ( rx_wb->flags ) );
-			netdev_rx_err ( netdev, iobuf, -EIO );
+			vlan_netdev_rx_err ( netdev, tag, iobuf, -EIO );
 		} else {
 			DBGC2 ( intelxl, "INTELXL %p RX %d complete (length "
 				"%zd)\n", intelxl, rx_idx, len );
-			netdev_rx ( netdev, iobuf );
+			vlan_netdev_rx ( netdev, tag, iobuf );
 		}
 		intelxl->rx.cons++;
 	}

src/drivers/net/intelxl.h

 /** Receive writeback descriptor */
 struct intelxl_rx_writeback_descriptor {
 	/** Reserved */
-	uint8_t reserved[8];
+	uint8_t reserved_a[2];
+	/** VLAN tag */
+	uint16_t vlan;
+	/** Reserved */
+	uint8_t reserved_b[4];
 	/** Flags */
 	uint32_t flags;
 	/** Length */
 /** Receive writeback descriptor complete */
 #define INTELXL_RX_WB_FL_DD 0x00000001UL
 
+/** Receive writeback descriptor VLAN tag present */
+#define INTELXL_RX_WB_FL_VLAN 0x00000004UL
+
 /** Receive writeback descriptor error */
 #define INTELXL_RX_WB_FL_RXE 0x00080000UL