netdev-dpdk: fix port addition for ports sharing same PCI id

Some NICs have only one PCI address associated with multiple ports. This
patch extends the dpdk-devargs option's format to cater for such devices.

To achieve that, this patch uses a new syntax that will be adapted and
implemented in future DPDK release (likely, v18.05):
    http://dpdk.org/ml/archives/dev/2017-December/084234.html

And since it's the DPDK duty to parse the (complete and full) syntax
and this patch is more likely to serve as an intermediate workaround,
here I take a simpler and shorter syntax from it (note it's allowed to
have only one category being provided):
    class=eth,mac=00:11:22:33:44:55:66

Also, old compatibility is kept. Users can still go on with using the
PCI id to add a port (if that's enough for them). Meaning, this patch
will not break anything.

This patch is basically based on the one from Ciara:
    https://mail.openvswitch.org/pipermail/ovs-dev/2017-October/339496.html

Cc: Loftus Ciara <ciara.loftus@intel.com>
Cc: Thomas Monjalon <thomas@monjalon.net>
Cc: Kevin Traynor <ktraynor@redhat.com>
Signed-off-by: Yuanhan Liu <yliu@fridaylinux.org>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>

Documentation/howto/dpdk.rst

@@ -48,6 +48,18 @@ number of dpdk devices found in the log file::
     $ ovs-vsctl add-port br0 dpdk-p1 -- set Interface dpdk-p1 type=dpdk \
         options:dpdk-devargs=0000:01:00.1
 
+Some NICs (i.e. Mellanox ConnectX-3) have only one PCI address associated
+with multiple ports. Using a PCI device like above won't work. Instead, below
+usage is suggested::
+
+    $ ovs-vsctl add-port br0 dpdk-p0 -- set Interface dpdk-p0 type=dpdk \
+        options:dpdk-devargs="class=eth,mac=00:11:22:33:44:55:01"
+    $ ovs-vsctl add-port br0 dpdk-p1 -- set Interface dpdk-p1 type=dpdk \
+        options:dpdk-devargs="class=eth,mac=00:11:22:33:44:55:02"
+
+Note: such syntax won't support hotplug. The hotplug is supposed to work with
+future DPDK release, v18.05.
+
 After the DPDK ports get added to switch, a polling thread continuously polls
 DPDK devices and consumes 100% of the core, as can be checked from ``top`` and
 ``ps`` commands::

lib/netdev-dpdk.c

@@ -1336,30 +1336,70 @@ netdev_dpdk_lookup_by_port_id(dpdk_port_t port_id)
     return NULL;
 }
 
+static dpdk_port_t
+netdev_dpdk_get_port_by_mac(const char *mac_str)
+{
+    dpdk_port_t port_id;
+    struct eth_addr mac, port_mac;
+
+    if (!eth_addr_from_string(mac_str, &mac)) {
+        VLOG_ERR("invalid mac: %s", mac_str);
+        return DPDK_ETH_PORT_ID_INVALID;
+    }
+
+    RTE_ETH_FOREACH_DEV (port_id) {
+        struct ether_addr ea;
+
+        rte_eth_macaddr_get(port_id, &ea);
+        memcpy(port_mac.ea, ea.addr_bytes, ETH_ADDR_LEN);
+        if (eth_addr_equals(mac, port_mac)) {
+            return port_id;
+        }
+    }
+
+    return DPDK_ETH_PORT_ID_INVALID;
+}
+
+/*
+ * Normally, a PCI id is enough for identifying a specific DPDK port.
+ * However, for some NICs having multiple ports sharing the same PCI
+ * id, using PCI id won't work then.
+ *
+ * To fix that, here one more method is introduced: "class=eth,mac=$MAC".
+ *
+ * Note that the compatibility is fully kept: user can still use the
+ * PCI id for adding ports (when it's enough for them).
+ */
 static dpdk_port_t
 netdev_dpdk_process_devargs(struct netdev_dpdk *dev,
                             const char *devargs, char **errp)
 {
-    /* Get the name up to the first comma. */
-    char *name = xmemdup0(devargs, strcspn(devargs, ","));
+    char *name;
     dpdk_port_t new_port_id = DPDK_ETH_PORT_ID_INVALID;
 
-    if (rte_eth_dev_get_port_by_name(name, &new_port_id)
-            || !rte_eth_dev_is_valid_port(new_port_id)) {
-        /* Device not found in DPDK, attempt to attach it */
-        if (!rte_eth_dev_attach(devargs, &new_port_id)) {
-            /* Attach successful */
-            dev->attached = true;
-            VLOG_INFO("Device '%s' attached to DPDK", devargs);
-        } else {
-            /* Attach unsuccessful */
-            new_port_id = DPDK_ETH_PORT_ID_INVALID;
-            VLOG_WARN_BUF(errp, "Error attaching device '%s' to DPDK",
-                          devargs);
+    if (strncmp(devargs, "class=eth,mac=", 14) == 0) {
+        new_port_id = netdev_dpdk_get_port_by_mac(&devargs[14]);
+    } else {
+        name = xmemdup0(devargs, strcspn(devargs, ","));
+        if (rte_eth_dev_get_port_by_name(name, &new_port_id)
+                || !rte_eth_dev_is_valid_port(new_port_id)) {
+            /* Device not found in DPDK, attempt to attach it */
+            if (!rte_eth_dev_attach(devargs, &new_port_id)) {
+                /* Attach successful */
+                dev->attached = true;
+                VLOG_INFO("Device '%s' attached to DPDK", devargs);
+            } else {
+                /* Attach unsuccessful */
+                new_port_id = DPDK_ETH_PORT_ID_INVALID;
+            }
         }
+        free(name);
+    }
+
+    if (new_port_id == DPDK_ETH_PORT_ID_INVALID) {
+        VLOG_WARN_BUF(errp, "Error attaching device '%s' to DPDK", devargs);
     }
 
-    free(name);
     return new_port_id;
 }