[PATCH] Updating the GEM MAC IP to properly filter out the multicast addresses

[Wasim, Bilal]

[PATCH] Updating the GEM MAC IP to properly filter out the multicast

addresses. The current code makes a bad assumption that the most-significant

byte of the MAC address is used to determine if the address is multicast or

unicast, but in reality only a single bit is used to determine this. This

caused IPv6 to not work.. Fix is now in place and has been tested with

ZCU102-A53 / IPv6 on a TAP interface. Works well..

 

Signed-off-by: Bilal Wasim <address@hidden>

---

hw/net/cadence_gem.c | 18 ++++++++++++------

1 file changed, 12 insertions(+), 6 deletions(-)

 

diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c

index b8be73d..f8bcbb3 100644

--- a/hw/net/cadence_gem.c

+++ b/hw/net/cadence_gem.c

@@ -315,6 +315,12 @@

 #define GEM_MODID_VALUE 0x00020118

+/* IEEE has specified that the most significant bit of the most significant byte be used for

+ * distinguishing between Unicast and Multicast addresses.

+ * If its a 1, that means multicast, 0 means unicast.   */

+#define IS_MULTICAST(address)           (((address[0] & 0x01) == 0x01) ? 1 : 0)

+#define IS_UNICAST(address)             (!IS_MULTICAST(address))

+

static inline uint64_t tx_desc_get_buffer(CadenceGEMState *s, uint32_t *desc)

{

     uint64_t ret = desc[0];

@@ -690,21 +696,21 @@ static int gem_mac_address_filter(CadenceGEMState *s, const uint8_t *packet)

     }

     /* Accept packets -w- hash match? */

-    if ((packet[0] == 0x01 && (s->regs[GEM_NWCFG] & GEM_NWCFG_MCAST_HASH)) ||

-        (packet[0] != 0x01 && (s->regs[GEM_NWCFG] & GEM_NWCFG_UCAST_HASH))) {

+    if ((IS_MULTICAST(packet) && (s->regs[GEM_NWCFG] & GEM_NWCFG_MCAST_HASH)) ||

+        (IS_UNICAST(packet)   && (s->regs[GEM_NWCFG] & GEM_NWCFG_UCAST_HASH))) {

         unsigned hash_index;

         hash_index = calc_mac_hash(packet);

         if (hash_index < 32) {

             if (s->regs[GEM_HASHLO] & (1<<hash_index)) {

-                return packet[0] == 0x01 ? GEM_RX_MULTICAST_HASH_ACCEPT :

-                                           GEM_RX_UNICAST_HASH_ACCEPT;

+                return IS_MULTICAST(packet) ? GEM_RX_MULTICAST_HASH_ACCEPT :

+                                              GEM_RX_UNICAST_HASH_ACCEPT;

             }

         } else {

             hash_index -= 32;

             if (s->regs[GEM_HASHHI] & (1<<hash_index)) {

-                return packet[0] == 0x01 ? GEM_RX_MULTICAST_HASH_ACCEPT :

-                                           GEM_RX_UNICAST_HASH_ACCEPT;

+                return IS_MULTICAST(packet) ? GEM_RX_MULTICAST_HASH_ACCEPT :

+                                              GEM_RX_UNICAST_HASH_ACCEPT;

             }

         }

     }

--

2.9.3