Fix: Correctly format the PCI path when checking device existence (#988)

There was some incorrect logic around the parsing of output from
`nvidia-smi`. Refer to issue #984 for more context.

pkg/worker/gpu_info.go

@@ -84,15 +84,16 @@ func (c *NvidiaInfoClient) AvailableGPUDevices() ([]int, error) {
 			continue
 		}
 
-		// PCI bus_id is shown to be "domain:bus:device.function", but the folder in /proc/driver/nvidia/gpus is just "bus:device.function"
-		busId := strings.ToLower(
-			strings.TrimPrefix(
-				strings.TrimSpace(parts[1]), domain,
-			),
-		)
+		smiBusIdParts := strings.Split(parts[1], ":")
+		if len(smiBusIdParts) != 3 {
+			return nil, fmt.Errorf("unexpected bus id format from nvidia-smi: %s", line)
+		}
+
+		// The bus id from nvidia-smi comes as xxxxxxxx:xx:xx.x so convert it to the format xxxx:xx:xx.x
+		systemBusId := strings.Join([]string{domain, smiBusIdParts[1], smiBusIdParts[2]}, ":")
 		gpuIndex := strings.TrimSpace(parts[2])
 
-		if exists, err := checkGPUExists(busId); err == nil && exists {
+		if exists, err := checkGPUExists(systemBusId); err == nil && exists {
 			index, err := strconv.Atoi(strings.TrimSpace(gpuIndex))
 			if err != nil {
 				return nil, err

pkg/worker/gpu_info_test.go

@@ -2,6 +2,7 @@ package worker
 
 import (
 	"os"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -58,6 +59,7 @@ func TestAvailableGPUDevicesAllVisibleDevices(t *testing.T) {
 	}
 
 	checkGPUExists = func(busId string) (bool, error) {
+		// check format matches xxxx:xx:xx.x
 		return true, nil
 	}
 
@@ -68,3 +70,34 @@ func TestAvailableGPUDevicesAllVisibleDevices(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, []int{0, 1, 2, 3, 4, 5, 6, 7}, devices)
 }
+
+func TestAvailableGPUDevicesWithNonZeroPCIDomain(t *testing.T) {
+	originalQueryDevices := queryDevices
+	defer func() { queryDevices = originalQueryDevices }()
+
+	originalCheckGPUExists := checkGPUExists
+	defer func() { checkGPUExists = originalCheckGPUExists }()
+
+	queryDevices = func() ([]byte, error) {
+		mockOutput := `0x0001, 00000001:23:00.0, 0, GPU-afb8c77a-62ef-a631-48d0-edc9670fef25`
+		return []byte(mockOutput), nil
+	}
+
+	checkGPUExists = func(busId string) (bool, error) {
+		// check format matches xxxx:xx:xx.x
+		parts := strings.Split(busId, ":")
+		assert.Equal(t, 3, len(parts))
+		assert.Equal(t, 4, len(parts[0]))
+		assert.Equal(t, 2, len(parts[1]))
+		assert.Equal(t, 4, len(parts[2]))
+		assert.Contains(t, parts[2], ".")
+		return true, nil
+	}
+
+	client := &NvidiaInfoClient{}
+	os.Setenv("NVIDIA_VISIBLE_DEVICES", "all")
+
+	devices, err := client.AvailableGPUDevices()
+	assert.NoError(t, err)
+	assert.Equal(t, []int{0}, devices)
+}