nvpci: do not warn when a GPU has no vfio-dev directory, and fix simpleLogger formatting

pkg/nvpci/logger.go

@@ -25,5 +25,5 @@ type logger interface {
 type simpleLogger struct{}
 
 func (l simpleLogger) Warningf(format string, v ...interface{}) {
-	log.Printf("WARNING: "+format, v)
+	log.Printf("WARNING: "+format, v...)
 }

pkg/nvpci/logger_test.go

@@ -0,0 +1,41 @@
+/**
+# Copyright (c) NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package nvpci
+
+import (
+	"bytes"
+	"log"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSimpleLoggerWarningf(t *testing.T) {
+	var buf bytes.Buffer
+	flags := log.Flags()
+	log.SetOutput(&buf)
+	log.SetFlags(0)
+	defer func() {
+		log.SetOutput(os.Stderr)
+		log.SetFlags(flags)
+	}()
+
+	simpleLogger{}.Warningf("unable to detect IOMMU FD for %s: %v", "0000:01:00.0", "no such file or directory")
+
+	require.Equal(t, "WARNING: unable to detect IOMMU FD for 0000:01:00.0: no such file or directory\n", buf.String())
+}

pkg/nvpci/nvpci.go

@@ -566,6 +566,12 @@ func getDriver(devicePath string) (string, error) {
 
 func getIOMMUFD(devicePath string) (string, error) {
 	content, err := os.ReadDir(path.Join(devicePath, "vfio-dev"))
+	// The vfio-dev directory only exists for devices that are bound to a VFIO
+	// driver on a kernel with VFIO device cdev support. For every other device,
+	// such as a GPU bound to the nvidia driver, there is no IOMMU FD to report.
+	if errors.Is(err, os.ErrNotExist) {
+		return "", nil
+	}
 	if err != nil {
 		return "", err
 	}

pkg/nvpci/nvpci_test.go

@@ -17,6 +17,7 @@
 package nvpci
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -196,6 +197,57 @@ func TestNvpciIOMMUFD(t *testing.T) {
 	}
 }
 
+type recordingLogger struct {
+	warnings []string
+}
+
+func (l *recordingLogger) Warningf(format string, v ...interface{}) {
+	l.warnings = append(l.warnings, fmt.Sprintf(format, v...))
+}
+
+func TestNvpciIOMMUFDNotBoundToVFIO(t *testing.T) {
+	nvpci, err := NewMockNvpci()
+	require.Nil(t, err, "Error creating NewMockNvpci")
+	defer nvpci.Cleanup()
+
+	logger := &recordingLogger{}
+	nvpci.logger = logger
+
+	err = nvpci.AddMockA100("0000:80:05.1", 0, nil)
+	require.Nil(t, err, "Error adding Mock A100 device to MockNvpci")
+
+	// A GPU that is bound to the nvidia driver has no vfio-dev directory.
+	deviceDir := filepath.Join(nvpci.pciDevicesRoot, "0000:80:05.1")
+	require.NoError(t, os.RemoveAll(filepath.Join(deviceDir, "vfio-dev")))
+
+	devices, err := nvpci.GetGPUs()
+	require.Nil(t, err, "Error getting GPUs")
+	require.Equal(t, 1, len(devices), "Wrong number of GPU devices")
+	require.Equal(t, "", devices[0].IommuFD, "IOMMUFD should be empty without a vfio-dev directory")
+	require.Empty(t, logger.warnings, "No warning expected for a device without a vfio-dev directory")
+}
+
+func TestNvpciIOMMUFDEmptyVFIODev(t *testing.T) {
+	nvpci, err := NewMockNvpci()
+	require.Nil(t, err, "Error creating NewMockNvpci")
+	defer nvpci.Cleanup()
+
+	logger := &recordingLogger{}
+	nvpci.logger = logger
+
+	err = nvpci.AddMockA100("0000:80:05.1", 0, nil)
+	require.Nil(t, err, "Error adding Mock A100 device to MockNvpci")
+
+	deviceDir := filepath.Join(nvpci.pciDevicesRoot, "0000:80:05.1")
+	require.NoError(t, os.RemoveAll(filepath.Join(deviceDir, "vfio-dev", "vfio8")))
+
+	devices, err := nvpci.GetGPUs()
+	require.Nil(t, err, "Error getting GPUs")
+	require.Equal(t, 1, len(devices), "Wrong number of GPU devices")
+	require.Equal(t, "", devices[0].IommuFD, "IOMMUFD should be empty without a vfio device entry")
+	require.Equal(t, []string{"unable to detect IOMMU FD for 0000:80:05.1: no iommufd device found"}, logger.warnings)
+}
+
 func TestNvpciNUMANode(t *testing.T) {
 	testCases := []struct {
 		Description string