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

2 files changed, 106 insertions, 20 deletions

diff --git a/python/vyos/utils/convert.py b/python/vyos/utils/convert.py
index ea07f9514..bdc9fd549 100644
--- a/python/vyos/utils/convert.py
+++ b/python/vyos/utils/convert.py
@@ -261,3 +261,56 @@ def encode_to_base64(input_string):
 
     # Decode the base64 bytes back to a string
     return encoded_string.decode('utf-8')
+
+
+def range_str_to_list(data: str) -> list[int]:
+    """
+    Convert a string of ranges to a sorted list of unique integers
+
+    Args:
+        data (str): Comma-separated ranges, e.g. '1-3,5,7-9'
+
+    Returns:
+        Sorted list of unique integers, e.g. ``[1, 2, 3, 5, 7, 8, 9]``.
+    """
+    if not data:
+        return []
+    result = []
+    for part in data.split(','):
+        if '-' in part:
+            start, end = part.split('-')
+            result.extend(range(int(start), int(end) + 1))
+        else:
+            result.append(int(part))
+    return sorted(set(result))
+
+
+def list_to_range_str(nums: list[int]) -> str:
+    """
+    Convert a list of integers to a compact string of ranges
+
+    Args:
+        nums: List of integers, e.g. [1, 2, 3, 5, 7, 8, 9].
+              Duplicates are removed and the list is sorted internally.
+
+    Returns:
+        Compact range string, e.g. '1-3,5,7-9'.
+        Returns '' for an empty input.
+    """
+    nums = sorted(set(nums))
+    if not nums:
+        return ''
+
+    ranges = []
+    start = end = nums[0]
+
+    for n in nums[1:]:
+        if n == end + 1:
+            end = n
+        else:
+            ranges.append(str(start) if start == end else f'{start}-{end}')
+            start = end = n
+
+    ranges.append(str(start) if start == end else f'{start}-{end}')
+
+    return ','.join(ranges)
diff --git a/python/vyos/vpp/config_verify.py b/python/vyos/vpp/config_verify.py
index da8e3d24b..228fcbc09 100644
--- a/python/vyos/vpp/config_verify.py
+++ b/python/vyos/vpp/config_verify.py
@@ -20,8 +20,10 @@ import psutil
 
 from vyos import ConfigError
 from vyos.base import Warning
+from vyos.utils.convert import range_str_to_list
 from vyos.utils.cpu import get_core_count as total_core_count, get_cpus
 from vyos.utils.dict import dict_search
+from vyos.utils.file import read_file
 
 from vyos.vpp.config_resource_checks import memory as mem_checks
 from vyos.vpp.config_resource_checks.resource_defaults import default_resource_map
@@ -54,6 +56,9 @@ _VPP_MEMBER_INTERFACE_REFS = [
 
 _VPP_INTERFACE_REFS = _VPP_FEATURE_INTERFACE_REFS + _VPP_MEMBER_INTERFACE_REFS
 
+# Line width used by ConfigError for message formatting
+LINE_WIDTH = 72
+
 
 def vpp_interface_in_use(
     iface: str, config: dict, match_vlans: bool = False, refs: list = None
@@ -217,12 +222,12 @@ def create_cpu_error_message(cpus_required: int, cpus_available: int = None) ->
 
     available_str = (
         (
-            '---'.ljust(72)
-            + 'Reserved:'.ljust(72)
-            + f'For system: {reserved_cpus}'.ljust(72)
-            + f'VPP main thread: 1'.ljust(72)
-            + '---'.ljust(72)
-            + 'Available:'.ljust(72)
+            '---'.ljust(LINE_WIDTH)
+            + 'Reserved:'.ljust(LINE_WIDTH)
+            + f'For system: {reserved_cpus}'.ljust(LINE_WIDTH)
+            + f'VPP main thread: 1'.ljust(LINE_WIDTH)
+            + '---'.ljust(LINE_WIDTH)
+            + 'Available:'.ljust(LINE_WIDTH)
             + f'Physical cores: {max(cpus_available, 0)}'
         )
         if cpus_available is not None
@@ -230,13 +235,13 @@ def create_cpu_error_message(cpus_required: int, cpus_available: int = None) ->
     )
 
     message = (
-        '---'.ljust(72)
-        + 'Total in the system:'.ljust(72)
-        + f'Physical cores: {total_core_count()}'.ljust(72)
-        + f'Logical cores: {logical_cores}'.ljust(72)
-        + '---'.ljust(72)
-        + 'Required:'.ljust(72)
-        + f'Physical cores: {cpus_required}'.ljust(72)
+        '---'.ljust(LINE_WIDTH)
+        + 'Total in the system:'.ljust(LINE_WIDTH)
+        + f'Physical cores: {total_core_count()}'.ljust(LINE_WIDTH)
+        + f'Logical cores: {logical_cores}'.ljust(LINE_WIDTH)
+        + '---'.ljust(LINE_WIDTH)
+        + 'Required:'.ljust(LINE_WIDTH)
+        + f'Physical cores: {cpus_required}'.ljust(LINE_WIDTH)
         + available_str
     )
 
@@ -251,7 +256,7 @@ def verify_vpp_minimum_cpus():
     min_cpus = default_resource_map.get('min_cpus')
     if total_core_count() < min_cpus:
         raise ConfigError(
-            'This system does not meet minimal requirements for VPP. '.ljust(72)
+            'This system does not meet minimal requirements for VPP. '.ljust(LINE_WIDTH)
             + create_cpu_error_message(min_cpus)
         )
 
@@ -329,10 +334,10 @@ def verify_vpp_memory(config: dict):
 
     if errors:
         raise ConfigError(
-            'Not enough free memory to start VPP! '.ljust(72)
-            + '. '.join([line.ljust(72) for line in errors.values()])
+            'Not enough free memory to start VPP! '.ljust(LINE_WIDTH)
+            + '. '.join([line.ljust(LINE_WIDTH) for line in errors.values()])
             + (
-                'To add HugePages memory please use command '.ljust(72)
+                'To add HugePages memory please use command '.ljust(LINE_WIDTH)
                 + '"set system option kernel memory hugepage-size ..." and reboot!'
                 if any(k in errors for k in ('2M', '1G'))
                 else ''
@@ -342,8 +347,19 @@ def verify_vpp_memory(config: dict):
 
 def verify_vpp_cpu_cores(cpu_cores: int):
     """
-    Verify that the system has enough available CPU cores
-    to run a given amount of worker processes (1 worker/core)
+    Verify that the system has enough available and isolated CPU cores.
+
+    Checks performed:
+      1. The host has enough physical cores (minus reserved) for the requested
+         cpu_cores count.
+      2. The kernel actually has at least cpu_cores isolated CPUs
+         (read from /sys/devices/system/cpu/isolated).
+
+    Args:
+        cpu_cores: Total number of VPP CPU cores (1 main + N-1 workers).
+
+    Raises:
+        ConfigError: When any of the checks fail.
     """
     total_cores = total_core_count()
     reserved_cpus = default_resource_map.get('reserved_cpu_cores')
@@ -351,10 +367,27 @@ def verify_vpp_cpu_cores(cpu_cores: int):
 
     if cpu_cores > available_cores:
         raise ConfigError(
-            f'Not enough free physical CPU cores for {cpu_cores} "cpu-cores" '.ljust(72)
+            f'Not enough free physical CPU cores for {cpu_cores} "cpu-cores" '.ljust(
+                LINE_WIDTH
+            )
             + create_cpu_error_message(cpu_cores, available_cores)
         )
 
+    # Read the set of CPUs the running kernel has actually isolated
+    isolated = read_file('/sys/devices/system/cpu/isolated')
+    isolated_cpus = range_str_to_list(isolated)
+
+    if cpu_cores > len(isolated_cpus):
+        raise ConfigError(
+            'Not enough isolated CPU cores available: '.ljust(LINE_WIDTH)
+            + f'{cpu_cores} requested, but only {len(isolated_cpus)} isolated'
+            f'{f" (CPU#{isolated})" if len(isolated_cpus) > 0 else ""}. '.ljust(
+                LINE_WIDTH
+            )
+            + 'To isolate CPUs please use command '.ljust(LINE_WIDTH)
+            + '"set system option kernel cpu isolate-cpus ..." save and reboot!'
+        )
+
 
 def verify_vpp_statseg_size(settings: dict):
     statseg_size = mem_checks.statseg_size(settings)