net, ixgbe: handle link local multicast addresses in SR-IOV mode

In SR-IOV mode the PF driver acts as the uplink port and is
used to send control packets e.g. lldpad, stp, etc.

   eth0.1     eth0.2     eth0
   VF         VF         PF
   |          |          |   <-- stand-in for uplink
   |          |          |
  --------------------------
  |  Embedded Switch       |
  --------------------------
              |
             MAC   <-- uplink

But the embedded switch is setup to forward multicast addresses
to all interfaces both VFs and PF and onto the physical link.
This results in reserved MAC addresses used by control protocols
to be forwarded over the switch onto the VF.

In the LLDP case the PF sends an LLDPDU and it is currently
being forwarded to all the VFs who then see the PF as a peer.
This is incorrect.

This patch adds the multicast addresses to the RAR table in the
hardware to prevent this behavior.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index b006ba0a9f42..45ded4be7b43 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -51,6 +51,25 @@ extern struct net_device *alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs,
 #define alloc_etherdev(sizeof_priv) alloc_etherdev_mq(sizeof_priv, 1)
 #define alloc_etherdev_mq(sizeof_priv, count) alloc_etherdev_mqs(sizeof_priv, count, count)
 
+/* Reserved Ethernet Addresses per IEEE 802.1Q */
+static const u8 br_reserved_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
+
+/**
+ * is_link_local -  Determine if given Eth addr is a link local mcast address.
+ * @addr: Pointer to a six-byte array containing the Ethernet address
+ *
+ * Return true if address is link local reserved addr (01:80:c2:00:00:0X) per
+ * IEEE 802.1Q 8.6.3 Frame filtering.
+ */
+static inline int is_link_local(const unsigned char *dest)
+{
+	__be16 *a = (__be16 *)dest;
+	static const __be16 *b = (const __be16 *)br_reserved_address;
+	static const __be16 m = cpu_to_be16(0xfff0);
+
+	return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
+}
+
 /**
  * is_zero_ether_addr - Determine if give Ethernet address is all zeros.
  * @addr: Pointer to a six-byte array containing the Ethernet address