vpp: T8268: Unify CPU settings into a single 'cpu-cores' node under 'resource-allocation'

Replace legacy VPP CPU settings (main-core, skip-cores, workers, corelist-workers) with a single resource-allocation cpu-cores option.

CPU assignment is now handled automatically: two cores are reserved for the system, the VPP main thread is placed on the first available core, and the remaining allocated cores are used as workers.
This simplifies configuration and ensures consistent CPU allocation.

2 files changed, 66 insertions, 50 deletions

diff --git a/src/conf_mode/vpp.py b/src/conf_mode/vpp.py
index 2634eae44..c961132d8 100755
--- a/src/conf_mode/vpp.py
+++ b/src/conf_mode/vpp.py
@@ -35,6 +35,7 @@ from vyos.ifconfig import Section
 from vyos.logger import getLogger
 from vyos.template import render
 from vyos.utils.boot import boot_configuration_complete
+from vyos.utils.cpu import get_available_cpus
 from vyos.utils.kernel import check_kmod
 from vyos.utils.kernel import unload_kmod
 from vyos.utils.kernel import list_loaded_modules
@@ -49,11 +50,7 @@ from vyos.vpp.config_verify import (
     verify_dev_driver,
     verify_vpp_minimum_cpus,
     verify_vpp_minimum_memory,
-    verify_vpp_settings_cpu,
-    verify_vpp_settings_cpu_corelist_workers,
-    verify_vpp_cpu_main_core,
-    verify_vpp_settings_cpu_skip_cores,
-    verify_vpp_settings_cpu_workers,
+    verify_vpp_cpu_cores,
     verify_vpp_memory,
     verify_vpp_statseg_size,
     verify_vpp_interfaces_dpdk_num_queues,
@@ -62,6 +59,7 @@ from vyos.vpp.config_verify import (
     verify_vpp_buffers,
 )
 from vyos.vpp.config_resource_checks import memory
+from vyos.vpp.config_resource_checks.resource_defaults import default_resource_map
 from vyos.vpp.config_filter import iface_filter_eth
 from vyos.vpp.utils import EthtoolGDrvinfo
 from vyos.vpp.configdb import JSONStorage
@@ -152,25 +150,28 @@ def _unload_module(module_name: str):
         raise
 
 
-def _get_workers_count(cpu_settings: dict) -> int:
-    if 'corelist_workers' in cpu_settings:
-        corelist_workers = []
-        for worker_range in cpu_settings['corelist_workers']:
-            core_numbers = worker_range.split('-')
-            corelist_workers.extend(
-                range(int(core_numbers[0]), int(core_numbers[-1]) + 1)
-            )
+def _configure_vpp_cpu_settings(config: dict):
+    """Configure VPP CPU settings: main-core, workers and skip-cores based on 'cpu-cores'"""
+    cpu_cores = int(config['settings']['resource_allocation']['cpu_cores'])
+    reserved_cpus = default_resource_map.get('reserved_cpu_cores')
 
-        return len(corelist_workers)
+    # Get sorted list of available CPU IDs
+    available = sorted({cpu['cpu'] for cpu in get_available_cpus()})
 
-    return int(cpu_settings.get('workers', 0))
+    if reserved_cpus < len(available):
+        main_core = available[reserved_cpus]  # first non-reserved CPU
+        config['settings']['cpu'] = {
+            'main_core': str(main_core),
+            'skip_cores': str(reserved_cpus),
+        }
+        if cpu_cores > 1:
+            config['settings']['cpu']['workers'] = str(cpu_cores - 1)
 
 
 def _normalize_buffers(config: dict):
     """Replace 'auto' buffers_per_numa with calculated value"""
     if config['settings']['buffers']['buffers_per_numa'] == 'auto':
-        workers = _get_workers_count(config['settings'].get('cpu', {}))
-        buffers = memory.buffers_required(config['settings'], workers)
+        buffers = memory.buffers_required(config['settings'])
         config['settings']['buffers']['buffers_per_numa'] = str(buffers)
 
 
@@ -398,15 +399,18 @@ def get_config(config=None):
                         )
                     if 'zero-copy' in iface_config['xdp_options']:
                         xdp_api_params['mode'] = 'zero-copy'
-                    if iface_config.get('rx_mode') in ('interrupt', 'adaptive') and any(
-                        key in config['settings'].get('cpu', {})
-                        for key in ('workers', 'corelist_workers')
+                    if (
+                        iface_config.get('rx_mode') in ('interrupt', 'adaptive')
+                        and int(config['settings']['resource_allocation']['cpu_cores'])
+                        > 1
                     ):
                         xdp_api_params['flags'] = 'no_syscall_lock'
                     iface_config['xdp_api_params'] = xdp_api_params
 
         # Buffer normalization (auto → computed)
         _normalize_buffers(config)
+        # Configure VPP main-core and workers 'cpu-cores' settings
+        _configure_vpp_cpu_settings(config)
 
     if removed_ifaces:
         config['removed_ifaces'] = removed_ifaces
@@ -507,38 +511,15 @@ def verify(config):
             raise ConfigError(f'Interface {iface} does not exist or is not Ethernet!')
 
     # Resource usage checks
-    cpu_settings = config['settings'].get('cpu', {})
-
-    if not any(key in cpu_settings for key in ('workers', 'corelist_workers')):
-        verify_vpp_minimum_cpus()
-
-    if 'cpu' in config['settings']:
-        # Check whether the workers and corelist-workers are configured properly
-        verify_vpp_settings_cpu(cpu_settings)
-
-        # Check if there are enough CPU cores to skip according to config
-        if 'skip_cores' in cpu_settings:
-            skip_cores = int(cpu_settings['skip_cores'])
-            verify_vpp_settings_cpu_skip_cores(skip_cores)
-
-        # Check if there are enough CPU cores to add workers
-        if 'workers' in cpu_settings:
-            verify_vpp_settings_cpu_workers(cpu_settings)
-
-        if 'main_core' in cpu_settings:
-            verify_vpp_cpu_main_core(cpu_settings)
-
-        # Check the CPU main core not falling to the corelist-workers
-        if 'corelist_workers' in cpu_settings:
-            verify_vpp_settings_cpu_corelist_workers(cpu_settings)
-
-    workers = _get_workers_count(config['settings'].get('cpu', {}))
+    cpu_cores = int(config['settings']['resource_allocation']['cpu_cores'])
+    verify_vpp_minimum_cpus()
+    verify_vpp_cpu_cores(cpu_cores)
 
     verify_vpp_main_heap_size(config['settings'])
     verify_vpp_statseg_size(config['settings'])
 
     # Check buffers
-    verify_vpp_buffers(config['settings'], workers)
+    verify_vpp_buffers(config['settings'])
 
     # Check if available memory is enough for current VPP config
     verify_vpp_memory(config)
@@ -579,13 +560,13 @@ def verify(config):
             if 'num_rx_queues' in iface_config['dpdk_options']:
                 rx_queues = int(iface_config['dpdk_options']['num_rx_queues'])
                 verify_vpp_interfaces_dpdk_num_queues(
-                    qtype='receive', num_queues=rx_queues, workers=workers
+                    qtype='receive', num_queues=rx_queues, workers=cpu_cores
                 )
 
             if 'num_tx_queues' in iface_config['dpdk_options']:
                 tx_queues = int(iface_config['dpdk_options']['num_tx_queues'])
                 verify_vpp_interfaces_dpdk_num_queues(
-                    qtype='transmit', num_queues=tx_queues, workers=workers
+                    qtype='transmit', num_queues=tx_queues, workers=cpu_cores
                 )
 
         # RX-mode verification
@@ -652,7 +633,7 @@ def verify(config):
                 f'Interface {iface_config["iface_name"]} is an xconnect member and cannot be removed'
             )
 
-    verify_routes_count(config['settings'], workers)
+    verify_routes_count(config['settings'])
 
 
 def generate(config):
diff --git a/src/migration-scripts/vpp/7-to-8 b/src/migration-scripts/vpp/7-to-8
index fa105a6b5..0b2f81b4c 100644
--- a/src/migration-scripts/vpp/7-to-8
+++ b/src/migration-scripts/vpp/7-to-8
@@ -20,6 +20,8 @@
 # Drop settings for nat workers (T8254)
 #
 # Delete 'ipsec' node and all settings and replace it with single 'ipsec-acceleration' flag (T8262)
+#
+# Unify CPU settings into a single 'cpu-cores' node under 'resource-allocation' (T8268)
 
 from vyos.configtree import ConfigTree
 
@@ -71,6 +73,38 @@ def _migrate_vpp_ipsec(config: ConfigTree) -> None:
         config.set(base + ['ipsec-acceleration'])
         config.delete(base + ['ipsec'])
 
+def _migrate_vpp_cpu(config: ConfigTree) -> None:
+    settings_path = ['vpp', 'settings']
+    cpu_path = settings_path + ['cpu']
+
+    if not config.exists(cpu_path):
+        # Nothing to do
+        return
+
+    # get number of configured workers
+    workers = 0
+
+    if config.exists(cpu_path + ['workers']):
+        workers += int(config.return_value(cpu_path + ['workers']))
+        # add main-core to total workers
+        workers += 1
+
+    if config.exists(cpu_path + ['corelist-workers']):
+        def _count_range(item: str) -> int:
+            if '-' in item:
+                start, end = map(int, item.split('-'))
+                return end - start + 1
+            return 1
+
+        tmp = config.return_values(cpu_path + ['corelist-workers'])
+        workers = sum(_count_range(item) for item in tmp) + 1  # + main core
+
+    # set 'resource-allocation cpu-cores'
+    if workers:
+        config.set(settings_path + ['resource-allocation', 'cpu-cores'], value=str(workers))
+
+    config.delete(cpu_path)
+
 
 def migrate(config: ConfigTree) -> None:
     if not config.exists(['vpp']):
@@ -81,3 +115,4 @@ def migrate(config: ConfigTree) -> None:
     _migrate_vpp_log(config)
     _migrate_vpp_nat44(config)
     _migrate_vpp_ipsec(config)
+    _migrate_vpp_cpu(config)