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introduce resolvePCIeRoot instead of resolveSysDevicesPath

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This commit is contained in:
Shingo Omura
2025-07-22 10:16:09 +09:00
parent f3d4b216f3
commit a4fb1562f4
1 changed files with 16 additions and 14 deletions
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30
staging/src/k8s.io/dynamic-resource-allocation/deviceattribute/pci_linux.go
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@@ -43,37 +43,36 @@ func GetPCIeRootAttributeByPCIBusID(pciBusID string) (DeviceAttribute, error) {
return DeviceAttribute{}, fmt.Errorf("invalid PCI Bus ID format: %s", pciBusID)
}
// e.g. /sys/devices/pci0000:01/...<intermediate PCI devices>.../0000:00:1f.0,
sysDevicesPath, err := resolveSysDevicesPath(pciBusID)
pcieRoot, err := resolvePCIeRoot(pciBusID)
if err != nil {
return DeviceAttribute{}, fmt.Errorf("failed to resolve sysfs path for PCI Bus ID %s: %w", pciBusID, err)
return DeviceAttribute{}, fmt.Errorf("failed to resolve PCIe Root Complex for PCI Bus ID %s: %w", pciBusID, err)
}
pciRootPart := strings.Split(strings.TrimPrefix(sysDevicesPath, sysfs.devices("")+"/"), "/")[0]
attr := DeviceAttribute{
Name: StandardDeviceAttributePCIeRoot,
Value: resourceapi.DeviceAttribute{StringValue: &pciRootPart},
Value: resourceapi.DeviceAttribute{StringValue: &pcieRoot},
}
return attr, nil
}
// resolveSysDevicesPath resolves the /sys/devices path from the PCI Bus ID
// in BDF (Bus-Device-Function) format, e.g., "0123:45:1e.7".
// resolvePCIeRoot resolves the PCIe Root for a given PCI Bus ID
// in BDF (Bus-Device-Function) format, e.g., "0123:45:1e.7",
// by inspecting sysfs(/sys/devices).
//
// ref: https://wiki.xenproject.org/wiki/Bus:Device.Function_(BDF)_Notation
//
// /sys/devices has a directory structure which reflects the hardware hierarchy in the system.
// Therefore, the device path may contain intermediate directories (devices).
// Thus, we can not simply find the device path from the PCIAddress.
// Fortunately, /sys/bus/pci/devices/<address> is a symlink to the actual device path in /sys/devices.
// Thus, we can not simply find the device path from the PCI Bus ID.
// But, fortunately, /sys/bus/pci/devices/<address> is a symlink to the actual device path in /sys/devices.
// So we can resolve the actual device path by reading the symlink at /sys/bus/pci/devices/<address>.
//
// For example, if the PCIAddress is "0000:00:1f.0",
// /sys/bus/pci/devices/0000:00:1f.0 points to
// /sys/devices/pci0000:01/...<intermediate PCI devices>.../0000:00:1f.0,
func resolveSysDevicesPath(pciBusID string) (string, error) {
// where "pci0000:01" is the PCIe Root.
func resolvePCIeRoot(pciBusID string) (string, error) {
// e.g. /sys/bus/pci/devices/0000:00:1f.0
sysBusPath := sysfs.bus(filepath.Join("pci", "devices", pciBusID))
@@ -89,9 +88,12 @@ func resolveSysDevicesPath(pciBusID string) (string, error) {
// targetAbs must be /sys/devices/pci0000:01/...<intermediate PCI devices>.../0000:00:1f.0
devicePathPrefix := sysfs.devices("pci")
if !strings.HasPrefix(targetAbs, devicePathPrefix) || filepath.Base(targetAbs) != pciBusID {
return "", fmt.Errorf("invalid symlink target for PCI Bus ID %s: %s", sysBusPath, targetAbs)
if !strings.HasPrefix(target, devicePathPrefix) || filepath.Base(target) != pciBusID {
return "", fmt.Errorf("invalid symlink target for PCI Bus ID %s: %s", sysBusPath, target)
}
return targetAbs, nil
// We need to extract the PCIe Root part, which is the first part of the path after /sys/devices/.
pcieRootPart := strings.Split(strings.TrimPrefix(target, sysfs.devices("")+"/"), "/")[0]
return pcieRootPart, nil
}