T7789: T7661: VPP prevent failing to set XDP driver on clouds

Some cloud NICs (ena, gve) fail to load XDP if all RX queues are configured. To
avoid this, we limit the number of queues to half of the maximum supported by the driver.

5 files changed, 147 insertions, 18 deletions

diff --git a/python/vyos/ethtool.py b/python/vyos/ethtool.py
index 6c362163c..22e066def 100644
--- a/python/vyos/ethtool.py
+++ b/python/vyos/ethtool.py
@@ -59,6 +59,7 @@ class Ethtool:
     _ring_buffer = None
     _driver_name = None
     _flow_control = None
+    _channels = ''
 
     def __init__(self, ifname):
         # Get driver used for interface
@@ -111,6 +112,11 @@ class Ethtool:
         if not bool(err):
             self._flow_control = loads(out)[0]
 
+        # Get information about NIC channels
+        out, err = popen(f'ethtool --show-channels {ifname}')
+        if not bool(err):
+            self._channels = out.lower()
+
     def check_auto_negotiation_supported(self):
         """ Check if the NIC supports changing auto-negotiation """
         return self._base_settings['supports-auto-negotiation']
@@ -199,3 +205,20 @@ class Ethtool:
                              'flow-control settings!')
 
         return 'on' if bool(self._flow_control['autonegotiate']) else 'off'
+
+    def get_channels(self, rx_tx_comb):
+        """
+        Get both the pre-set maximum and current value for a given channel type.
+
+        Args:
+            rx_tx_comb (str): Channel type, one of "rx", "tx", or "combined".
+
+        Returns:
+            list[int]: [maximum, current] values for the channel,
+                       or an empty list if not supported.
+        """
+        if rx_tx_comb not in ['rx', 'tx', 'combined']:
+            raise ValueError('Channel type must be either "rx", "tx" or "combined"')
+        matches = re.findall(rf'{rx_tx_comb}:\s+(\d+)', self._channels)
+
+        return [int(value) for value in matches]
diff --git a/python/vyos/ifconfig/ethernet.py b/python/vyos/ifconfig/ethernet.py
index 6c7b230ca..70da837b9 100644
--- a/python/vyos/ifconfig/ethernet.py
+++ b/python/vyos/ifconfig/ethernet.py
@@ -455,6 +455,23 @@ class EthernetIf(Interface):
             print(f'could not set "{rx_tx}" ring-buffer for {ifname}')
         return output
 
+    def set_channels(self, rx_tx_comb, queues):
+        """
+        Example:
+        >>> from vyos.ifconfig import EthernetIf
+        >>> i = EthernetIf('eth0')
+        >>> i.set_channels('rx', 2)
+        """
+        ifname = self.config['ifname']
+        cmd = f'ethtool --set-channels {ifname} {rx_tx_comb} {queues}'
+        output, code = self._popen(cmd)
+        # ethtool error codes:
+        #  80 - value already setted
+        #  81 - does not possible to set value
+        if code and code != 80:
+            print(f'could not set "{rx_tx_comb}" channel for {ifname}')
+        return output
+
     def set_switchdev(self, enable):
         ifname = self.config['ifname']
         addr, code = self._popen(
diff --git a/python/vyos/vpp/control_host.py b/python/vyos/vpp/control_host.py
index db1a492c9..2ebfd180b 100644
--- a/python/vyos/vpp/control_host.py
+++ b/python/vyos/vpp/control_host.py
@@ -24,6 +24,7 @@ from time import sleep
 from pyroute2 import IPRoute
 
 from vyos.ethtool import Ethtool
+from vyos.ifconfig import EthernetIf
 from vyos.vpp.utils import EthtoolGDrvinfo
 
 
@@ -376,3 +377,40 @@ def flush_ip(iface_name: str) -> None:
     """
     iproute = IPRoute()
     iproute.flush_addr(label=iface_name)
+
+
+def get_eth_channels(iface_name: str) -> dict:
+    """
+    Get the current hardware queue counts for channels of an interface using ethtool.
+
+    Args:
+        iface_name (str): name of an interface
+
+    Returns:
+        dict: Mapping of channel types to their current values:
+              - 'rx' (int | None): RX channel count.
+              - 'tx' (int | None): TX channel count.
+              - 'combined' (int | None): Combined channel count.
+              Returns None if the channel type is not supported.
+    """
+    ethtool = Ethtool(iface_name)
+
+    channels = {}
+    for channel in ['rx', 'tx', 'combined']:
+        queues_list = ethtool.get_channels(channel)
+        channels[channel] = queues_list[-1] if (len(queues_list) == 2) else None
+
+    return channels
+
+
+def set_eth_channels(iface_name: str, channels: dict) -> None:
+    """Configure the number of RX, TX, or combined channels for an interface.
+
+    Args:
+        iface_name (str): name of an interface
+        channels (dict): channels to set
+    """
+    interface = EthernetIf(iface_name)
+    for channel, value in channels.items():
+        if value:
+            interface.set_channels(channel, value)
diff --git a/python/vyos/vpp/control_vpp.py b/python/vyos/vpp/control_vpp.py
index cb8da50a6..2ee253b45 100644
--- a/python/vyos/vpp/control_vpp.py
+++ b/python/vyos/vpp/control_vpp.py
@@ -351,7 +351,7 @@ class VPPControl:
         self,
         host_if: str,
         name: str,
-        rxq_num: int = 0,
+        rxq_num: int = 65535,
         rxq_size: int = 0,
         txq_size: int = 0,
         mode: Literal['auto', 'copy', 'zero-copy'] = 'auto',
diff --git a/src/conf_mode/vpp.py b/src/conf_mode/vpp.py
index 61b10406f..bd7ff173f 100755
--- a/src/conf_mode/vpp.py
+++ b/src/conf_mode/vpp.py
@@ -112,6 +112,9 @@ drivers_support_interrupt: dict[str, list] = {
     'virtio_net': ['xdp'],
 }
 
+# drivers that require changing channels (half the maximum number of RX/TX queues)
+ethtool_channels_change_drv: list[str] = ['ena', 'gve']
+
 
 def _load_module(module_name: str):
     """
@@ -171,6 +174,25 @@ def _normalize_buffers(config: dict):
         config['settings']['buffers']['buffers_per_numa'] = str(buffers)
 
 
+def _get_max_xdp_rx_queues(config: dict):
+    """
+    Count max number of RX queues for XDP driver
+    - If the interface driver is in `ethtool_channels_change_drv`
+      only half of the available queues are used (to avoid NIC issues)
+    - For other interface drivers the full number of queues is returned.
+    - If neither `rx` nor `combined` is set, return 1.
+    """
+    for key in ('rx', 'combined'):
+        value = config['channels'].get(key)
+        if value:
+            if config['original_driver'] in ethtool_channels_change_drv:
+                return max(1, int(value) // 2)
+            else:
+                return int(value)
+
+    return 1
+
+
 def get_config(config=None):
     # use persistent config to store interfaces data between executions
     # this is required because some interfaces after they are connected
@@ -270,6 +292,20 @@ def get_config(config=None):
         _normalize_buffers(effective_config)
         config['effective'] = effective_config
 
+    # Save important info about all interfaces that cannot be retrieved later
+    # Add new interfaces (only if they are first time seen in a config)
+    for iface, iface_config in config.get('settings', {}).get('interface', {}).items():
+        if iface not in effective_config.get('settings', {}).get('interface', {}):
+            eth_ifaces_persist[iface] = {
+                'original_driver': EthtoolGDrvinfo(iface).driver,
+            }
+            eth_ifaces_persist[iface]['bus_id'] = control_host.get_bus_name(iface)
+            eth_ifaces_persist[iface]['dev_id'] = control_host.get_dev_id(iface)
+            eth_ifaces_persist[iface]['channels'] = control_host.get_eth_channels(iface)
+
+    # Return to config dictionary
+    config['persist_config'] = eth_ifaces_persist
+
     if 'settings' in config:
         if 'interface' in config['settings']:
             for iface, iface_config in config['settings']['interface'].items():
@@ -330,7 +366,8 @@ def get_config(config=None):
                         'txq_size': int(iface_config['xdp_options']['tx_queue_size']),
                     }
                     if iface_config['xdp_options']['num_rx_queues'] == 'all':
-                        xdp_api_params['rxq_num'] = 0
+                        # 65535 is used as special value to request all available queues
+                        xdp_api_params['rxq_num'] = 65535
                     else:
                         xdp_api_params['rxq_num'] = int(
                             iface_config['xdp_options']['num_rx_queues']
@@ -363,18 +400,6 @@ def get_config(config=None):
                     iface_filter_eth(conf, iface)
                 set_dependents(dependency, conf, iface)
 
-    # Save important info about all interfaces that cannot be retrieved later
-    # Add new interfaces (only if they are first time seen in a config)
-    for iface, iface_config in config.get('settings', {}).get('interface', {}).items():
-        if iface not in effective_config.get('settings', {}).get('interface', {}):
-            eth_ifaces_persist[iface] = {
-                'original_driver': config['settings']['interface'][iface][
-                    'kernel_module'
-                ],
-            }
-            eth_ifaces_persist[iface]['bus_id'] = control_host.get_bus_name(iface)
-            eth_ifaces_persist[iface]['dev_id'] = control_host.get_dev_id(iface)
-
     # kernel-interfaces dependency
     if effective_config.get('kernel_interfaces'):
         for iface in config.get('kernel_interfaces', {}):
@@ -399,9 +424,6 @@ def get_config(config=None):
         config['pppoe_ifaces'] = pppoe_map_ifaces
         set_dependents('pppoe_server', conf)
 
-    # Return to config dictionary
-    config['persist_config'] = eth_ifaces_persist
-
     return config
 
 
@@ -493,6 +515,14 @@ def verify(config):
                 )
         if iface_config['driver'] == 'xdp' and 'xdp_options' in iface_config:
             if iface_config['xdp_options']['num_rx_queues'] != 'all':
+                rx_queues = iface_config['xdp_api_params']['rxq_num']
+                max_rx_queues = _get_max_xdp_rx_queues(config['persist_config'][iface])
+                if rx_queues > max_rx_queues:
+                    raise ConfigError(
+                        f'Maximum supported number of RX queues for interface {iface} is {max_rx_queues}. '
+                        f'Please set "xdp-options num-rx-queues" to {max_rx_queues} or fewer'
+                    )
+
                 Warning(f'Not all RX queues will be connected to VPP for {iface}!')
 
         if iface_config['driver'] == 'xdp' and 'dpdk_options' in iface_config:
@@ -601,11 +631,13 @@ def initialize_interface(iface, driver, iface_config) -> None:
         iface_new_name: str = control_host.get_eth_name(iface_config['dev_id'])
         control_host.rename_iface(iface_new_name, iface)
 
-    # XDP - rename an interface, disable promisc and XDP
+    # XDP - rename an interface, disable promisc and XDP, set original channels
     if driver == 'xdp':
         control_host.set_promisc(f'defunct_{iface}', 'off')
         control_host.rename_iface(f'defunct_{iface}', iface)
         control_host.xdp_remove(iface)
+        if iface_config['original_driver'] in ethtool_channels_change_drv:
+            control_host.set_eth_channels(iface, iface_config['channels'])
 
     # Rename Mellanox NIC to a normal name
     try:
@@ -720,6 +752,25 @@ def apply(config):
                 # add XDP interfaces
                 if iface_config['driver'] == 'xdp':
                     control_host.rename_iface(iface, f'defunct_{iface}')
+
+                    # Some cloud NICs fail to load XDP if all RX queues are configured. To avoid this,
+                    # we limit the number of queues to half of the maximum supported by the driver.
+                    if (
+                        config['persist_config'][iface]['original_driver']
+                        in ethtool_channels_change_drv
+                    ):
+                        max_rx_queues = _get_max_xdp_rx_queues(
+                            config['persist_config'][iface]
+                        )
+                        channels_orig = config['persist_config'][iface]['channels']
+                        channels = {}
+                        if channels_orig.get('rx'):
+                            channels = {'rx': max_rx_queues, 'tx': max_rx_queues}
+                        if channels_orig.get('combined'):
+                            channels['combined'] = max_rx_queues
+                        if channels:
+                            control_host.set_eth_channels(f'defunct_{iface}', channels)
+
                     vpp_control.xdp_iface_create(
                         host_if=f'defunct_{iface}',
                         name=iface,