gpu: Add GetNvidiaDeviceByPciBusID and fix GetGPUByPciBusID

- Add GetNvidiaDeviceByPciBusID to return any NVIDIA PCI device
  (GPU, NVSwitch, etc.) at a given PCI Bus ID
- Refactor GetGPUByPciBusID to wrap GetNvidiaDeviceByPciBusID
  and filter to return only GPUs (returns nil for non-GPU devices)
- Rename internal function to getNvidiaDeviceByPciBusID

Signed-off-by: Zvonko Kaiser <zkaiser@nvidia.com>

Author: zvonkok

pkg/nvpci/nvpci.go

@@ -56,6 +56,7 @@ type Interface interface {
 	GetGPUs() ([]*NvidiaPCIDevice, error)
 	GetGPUByIndex(int) (*NvidiaPCIDevice, error)
 	GetGPUByPciBusID(string) (*NvidiaPCIDevice, error)
+	GetNvidiaDeviceByPciBusID(string) (*NvidiaPCIDevice, error)
 	GetNetworkControllers() ([]*NvidiaPCIDevice, error)
 	GetPciBridges() ([]*NvidiaPCIDevice, error)
 	GetDPUs() ([]*NvidiaPCIDevice, error)
@@ -211,7 +212,7 @@ func (p *nvpci) GetAllDevices() ([]*NvidiaPCIDevice, error) {
 	cache := make(map[string]*NvidiaPCIDevice)
 	for _, deviceDir := range deviceDirs {
 		deviceAddress := deviceDir.Name()
-		nvdevice, err := p.getGPUByPciBusID(deviceAddress, cache)
+		nvdevice, err := p.getNvidiaDeviceByPciBusID(deviceAddress, cache)
 		if err != nil {
 			return nil, fmt.Errorf("error constructing NVIDIA PCI device %s: %v", deviceAddress, err)
 		}
@@ -235,13 +236,27 @@ func (p *nvpci) GetAllDevices() ([]*NvidiaPCIDevice, error) {
 	return nvdevices, nil
 }
 
-// GetGPUByPciBusID constructs an NvidiaPCIDevice for the specified address (PCI Bus ID).
+// GetGPUByPciBusID returns an NvidiaPCIDevice for the specified address (PCI Bus ID)
+// only if the device is a GPU. Returns nil if the device exists but is not a GPU.
 func (p *nvpci) GetGPUByPciBusID(address string) (*NvidiaPCIDevice, error) {
-	// Pass nil as to force reading device information from sysfs.
-	return p.getGPUByPciBusID(address, nil)
+	dev, err := p.GetNvidiaDeviceByPciBusID(address)
+	if err != nil {
+		return nil, err
+	}
+	if dev == nil || !dev.IsGPU() {
+		return nil, nil
+	}
+	return dev, nil
+}
+
+// GetNvidiaDeviceByPciBusID constructs an NvidiaPCIDevice for the specified
+// address (PCI Bus ID). This returns any NVIDIA PCI device at the given
+// address, including GPUs, NVSwitches, and other NVIDIA devices.
+func (p *nvpci) GetNvidiaDeviceByPciBusID(address string) (*NvidiaPCIDevice, error) {
+	return p.getNvidiaDeviceByPciBusID(address, nil)
 }
 
-func (p *nvpci) getGPUByPciBusID(address string, cache map[string]*NvidiaPCIDevice) (*NvidiaPCIDevice, error) {
+func (p *nvpci) getNvidiaDeviceByPciBusID(address string, cache map[string]*NvidiaPCIDevice) (*NvidiaPCIDevice, error) {
 	if cache != nil {
 		if pciDevice, exists := cache[address]; exists {
 			return pciDevice, nil
@@ -357,7 +372,7 @@ func (p *nvpci) getGPUByPciBusID(address string, cache map[string]*NvidiaPCIDevi
 	physFnAddress, err := filepath.EvalSymlinks(path.Join(devicePath, "physfn"))
 	switch {
 	case err == nil:
-		physFn, err := p.getGPUByPciBusID(filepath.Base(physFnAddress), cache)
+		physFn, err := p.getNvidiaDeviceByPciBusID(filepath.Base(physFnAddress), cache)
 		if err != nil {
 			return nil, fmt.Errorf("unable to detect physfn for %s: %v", address, err)
 		}