vpp: T8460: Use isolated cpus for VPP cpu-cores

VPP CPU core assignment now uses kernel-isolated CPUs (from /sys/devices/system/cpu/isolated) with explicit corelist-workers instead of computing offsets from available cores with skip-cores/workers. Added validation that enough CPUs are actually isolated before VPP starts, and that isolate-cpus config only references existing CPU IDs. Moved smoketest for kernel option 'isolate-cpus' to test_vpp.py

3 files changed, 85 insertions, 13 deletions

diff --git a/src/conf_mode/system_option.py b/src/conf_mode/system_option.py
index 41b9a23bb..b7487de8a 100755
--- a/src/conf_mode/system_option.py
+++ b/src/conf_mode/system_option.py
@@ -28,7 +28,10 @@ from vyos.configverify import verify_interface_exists
 from vyos.system import grub_util
 from vyos.template import render
 from vyos.utils.boot import boot_configuration_complete
+from vyos.utils.convert import range_str_to_list
+from vyos.utils.convert import list_to_range_str
 from vyos.utils.cpu import get_cpus
+from vyos.utils.cpu import get_available_cpus
 from vyos.utils.dict import dict_search
 from vyos.utils.file import write_file
 from vyos.utils.file import read_file
@@ -44,6 +47,7 @@ from vyos import ConfigError
 from vyos import airbag
 
 from vyos.vpp.config_resource_checks import memory as mem_check
+from vyos.vpp.config_resource_checks.resource_defaults import default_resource_map
 
 airbag.enable()
 
@@ -239,6 +243,29 @@ def verify(options):
                 f'AMD pstate driver cannot be used with "{cpu_vendor}" CPU!'
             )
 
+        isolate_cpus = dict_search('kernel.cpu.isolate_cpus', options)
+        if isolate_cpus:
+            available_cores = sorted({int(cpu['cpu']) for cpu in get_available_cpus()})
+            cpus_list = range_str_to_list(isolate_cpus)
+            reserved_cpus = default_resource_map.get('reserved_cpu_cores')
+
+            cpus_available = len(available_cores) - reserved_cpus
+            if len(cpus_list) > cpus_available:
+                raise ConfigError(
+                    f'Cannot isolate {len(cpus_list)} CPUs ({isolate_cpus}): '
+                    f'only {cpus_available} of {len(available_cores)} physical cores '
+                    f'are available ({reserved_cpus} reserved for the system)'
+                )
+
+            not_available = [cpu for cpu in cpus_list if cpu not in available_cores]
+            if not_available:
+                not_available_str = list_to_range_str(not_available)
+                available_str = list_to_range_str(available_cores)
+                raise ConfigError(
+                    f'CPU(s) {not_available_str} do not exist on this system. '
+                    f'Available CPUs: {available_str}'
+                )
+
         _, hp_memory_bytes = _get_total_hugepages_and_memory(
             options['kernel'].get('memory', {})
         )
diff --git a/src/conf_mode/vpp.py b/src/conf_mode/vpp.py
index 33a4023af..342d58fca 100755
--- a/src/conf_mode/vpp.py
+++ b/src/conf_mode/vpp.py
@@ -38,8 +38,10 @@ 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.convert import range_str_to_list
+from vyos.utils.convert import list_to_range_str
 from vyos.utils.dict import dict_search
+from vyos.utils.file import read_file
 from vyos.utils.kernel import check_kmod
 from vyos.utils.kernel import unload_kmod
 from vyos.utils.kernel import list_loaded_modules
@@ -62,7 +64,6 @@ 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.utils import cli_ethernet_with_vifs_ifaces
@@ -168,21 +169,27 @@ def _unload_module(module_name: str):
 
 
 def _configure_vpp_cpu_settings(config: dict):
-    """Configure VPP CPU settings: main-core, workers and skip-cores based on 'cpu-cores'"""
+    """Configure VPP CPU settings: main-core and corelist-workers based on 'cpu-cores'.
+
+    Reads the actually-isolated CPUs from the running kernel
+    (/sys/devices/system/cpu/isolated) and assigns:
+      - main_core: the first isolated CPU (index 0)
+      - corelist_workers: the next (cpu_cores - 1) isolated CPUs
+    """
     cpu_cores = int(config['settings']['resource_allocation']['cpu_cores'])
-    reserved_cpus = default_resource_map.get('reserved_cpu_cores')
+    # Use the system's actual isolated CPUs, not config values which may
+    # require a reboot to take effect
+    isolated = read_file('/sys/devices/system/cpu/isolated')
+    cpus_isolated = range_str_to_list(isolated)
 
-    # Get sorted list of available CPU IDs
-    available = sorted({cpu['cpu'] for cpu in get_available_cpus()})
+    if cpu_cores <= len(cpus_isolated):
+        # First isolated CPU is the VPP main thread; remaining are workers
+        config['settings']['cpu'] = {'main_core': str(cpus_isolated[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)
+            config['settings']['cpu']['corelist_workers'] = list_to_range_str(
+                cpus_isolated[1:cpu_cores]
+            )
 
 
 def _normalize_buffers(config: dict):
diff --git a/src/tests/test_utils.py b/src/tests/test_utils.py
index 9cf6f7a1e..5712836c4 100644
--- a/src/tests/test_utils.py
+++ b/src/tests/test_utils.py
@@ -37,3 +37,41 @@ class TestVyOSUtils(TestCase):
         self.assertEqual(list_strip(lst, rsb, right=True), ['a', 'b', 'c'])
         self.assertEqual(list_strip(lst, non), [])
         self.assertEqual(list_strip(sub, lst), [])
+
+    def test_range_str_to_list(self):
+        from vyos.utils.convert import range_str_to_list
+
+        # basic cases
+        self.assertEqual(range_str_to_list('1-3'), [1, 2, 3])
+        self.assertEqual(range_str_to_list('1-3,5,7-8'), [1, 2, 3, 5, 7, 8])
+        self.assertEqual(range_str_to_list('3'), [3])
+        # empty string
+        self.assertEqual(range_str_to_list(''), [])
+        # unordered input
+        self.assertEqual(range_str_to_list('5,1-3,4'), [1, 2, 3, 4, 5])
+        self.assertEqual(range_str_to_list('7-9,1-3'), [1, 2, 3, 7, 8, 9])
+        # overlapping ranges
+        self.assertEqual(range_str_to_list('1-5,3-7'), [1, 2, 3, 4, 5, 6, 7])
+        self.assertEqual(range_str_to_list('1-3,2-4,3-5'), [1, 2, 3, 4, 5])
+        # duplicated values
+        self.assertEqual(range_str_to_list('1,1,2,2,3'), [1, 2, 3])
+        self.assertEqual(range_str_to_list('5,1-3,2,3'), [1, 2, 3, 5])
+        # adjacent ranges
+        self.assertEqual(range_str_to_list('1-3,4-6'), [1, 2, 3, 4, 5, 6])
+
+    def test_list_to_range_str(self):
+        from vyos.utils.convert import list_to_range_str
+
+        # basic cases
+        self.assertEqual(list_to_range_str([1, 2, 3]), '1-3')
+        self.assertEqual(list_to_range_str([1, 2, 3, 5, 7, 8]), '1-3,5,7-8')
+        self.assertEqual(list_to_range_str([1, 3]), '1,3')
+        self.assertEqual(list_to_range_str([3]), '3')
+        # empty list
+        self.assertEqual(list_to_range_str([]), '')
+        # unordered input
+        self.assertEqual(list_to_range_str([5, 1, 2, 3, 4]), '1-5')
+        self.assertEqual(list_to_range_str([7, 8, 9, 1, 2, 3]), '1-3,7-9')
+        # duplicated values
+        self.assertEqual(list_to_range_str([1, 1, 2, 2, 3, 3]), '1-3')
+        self.assertEqual(list_to_range_str([5, 1, 2, 2, 3, 5]), '1-3,5')