Add option to load NVIDIA kernel modules

These changes add a --load-kernel-modules option to the
nvidia-ctk system commands. If specified the NVIDIA kernel modules
(nvidia, nvidia-uvm, and nvidia-modeset) are loaded before any
operations on device nodes are performed.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

cmd/nvidia-ctk/system/create-dev-char-symlinks/create-dev-char-symlinks.go

@@ -24,6 +24,7 @@ import (
 	"strings"
 	"syscall"
 
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/system"
 	"github.com/fsnotify/fsnotify"
 	"github.com/sirupsen/logrus"
 	"github.com/urfave/cli/v2"
@@ -43,6 +44,7 @@ type config struct {
 	dryRun            bool
 	watch             bool
 	createAll         bool
+	loadKernelModules bool
 }
 
 // NewCommand constructs a command sub-command with the specified logger
@@ -97,6 +99,12 @@ func (m command) build() *cli.Command {
 			Destination: &cfg.createAll,
 			EnvVars:     []string{"CREATE_ALL"},
 		},
+		&cli.BoolFlag{
+			Name:        "load-kernel-modules",
+			Usage:       "Load the NVIDIA kernel modules before creating symlinks. This is only applicable when --create-all is set.",
+			Destination: &cfg.loadKernelModules,
+			EnvVars:     []string{"LOAD_KERNEL_MODULES"},
+		},
 		&cli.BoolFlag{
 			Name:        "dry-run",
 			Usage:       "If set, the command will not create any symlinks.",
@@ -114,6 +122,11 @@ func (m command) validateFlags(r *cli.Context, cfg *config) error {
 		return fmt.Errorf("create-all and watch are mutually exclusive")
 	}
 
+	if cfg.loadKernelModules && !cfg.createAll {
+		m.logger.Warn("load-kernel-modules is only applicable when create-all is set; ignoring")
+		cfg.loadKernelModules = false
+	}
+
 	return nil
 }
 
@@ -137,6 +150,7 @@ func (m command) run(c *cli.Context, cfg *config) error {
 		WithDriverRoot(cfg.driverRoot),
 		WithDryRun(cfg.dryRun),
 		WithCreateAll(cfg.createAll),
+		WithLoadKernelModules(cfg.loadKernelModules),
 	)
 	if err != nil {
 		return fmt.Errorf("failed to create symlink creator: %v", err)
@@ -192,6 +206,7 @@ type linkCreator struct {
 	devCharPath       string
 	dryRun            bool
 	createAll         bool
+	loadKernelModules bool
 }
 
 // Creator is an interface for creating symlinks to /dev/nv* devices in /dev/char.
@@ -218,6 +233,19 @@ func NewSymlinkCreator(opts ...Option) (Creator, error) {
 		c.devCharPath = defaultDevCharPath
 	}
 
+	if c.loadKernelModules {
+		s, err := system.New(
+			system.WithLogger(c.logger),
+			system.WithDryRun(c.dryRun),
+		)
+		if err != nil {
+			return nil, err
+		}
+		if err := s.LoadNVIDIAKernelModules(); err != nil {
+			return nil, fmt.Errorf("failed to load NVIDIA kernel modules: %v", err)
+		}
+	}
+
 	if c.createAll {
 		lister, err := newAllPossible(c.logger, c.driverRoot)
 		if err != nil {
@@ -265,6 +293,13 @@ func WithCreateAll(createAll bool) Option {
 	}
 }
 
+// WithLoadKernelModules sets the loadKernelModules flag for the linkCreator.
+func WithLoadKernelModules(loadKernelModules bool) Option {
+	return func(lc *linkCreator) {
+		lc.loadKernelModules = loadKernelModules
+	}
+}
+
 // CreateLinks creates symlinks for all NVIDIA device nodes found in the driver root.
 func (m linkCreator) CreateLinks() error {
 	deviceNodes, err := m.lister.DeviceNodes()

cmd/nvidia-ctk/system/create-device-nodes/create-device-nodes.go

@@ -34,6 +34,8 @@ type options struct {
 	dryRun bool
 
 	control bool
+
+	loadKernelModules bool
 }
 
 // NewCommand constructs a command sub-command with the specified logger
@@ -72,6 +74,11 @@ func (m command) build() *cli.Command {
 			Usage:       "create all control device nodes: nvidiactl, nvidia-modeset, nvidia-uvm, nvidia-uvm-tools",
 			Destination: &opts.control,
 		},
+		&cli.BoolFlag{
+			Name:        "load-kernel-modules",
+			Usage:       "load the NVIDIA Kernel Modules before creating devices nodes",
+			Destination: &opts.loadKernelModules,
+		},
 		&cli.BoolFlag{
 			Name:        "dry-run",
 			Usage:       "if set, the command will not create any symlinks.",
@@ -92,6 +99,7 @@ func (m command) run(c *cli.Context, opts *options) error {
 	s, err := system.New(
 		system.WithLogger(m.logger),
 		system.WithDryRun(opts.dryRun),
+		system.WithLoadKernelModules(opts.loadKernelModules),
 	)
 	if err != nil {
 		return fmt.Errorf("failed to create library: %v", err)

internal/system/options.go

@@ -34,3 +34,10 @@ func WithDryRun(dryRun bool) Option {
 		i.dryRun = dryRun
 	}
 }
+
+// WithLoadKernelModules sets the load kernel modules flag
+func WithLoadKernelModules(loadKernelModules bool) Option {
+	return func(i *Interface) {
+		i.loadKernelModules = loadKernelModules
+	}
+}

internal/system/system.go

@@ -19,6 +19,7 @@ package system
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 
@@ -31,7 +32,7 @@ import (
 type Interface struct {
 	logger            *logrus.Logger
 	dryRun            bool
-
+	loadKernelModules bool
 	nvidiaDevices     nvidiaDevices
 }
 
@@ -44,6 +45,12 @@ func New(opts ...Option) (*Interface, error) {
 		opt(i)
 	}
 
+	if i.loadKernelModules {
+		if err := i.LoadNVIDIAKernelModules(); err != nil {
+			return nil, fmt.Errorf("failed to load kernel modules: %v", err)
+		}
+	}
+
 	devices, err := devices.GetNVIDIADevices()
 	if err != nil {
 		return nil, fmt.Errorf("failed to create devices info: %v", err)
@@ -108,6 +115,26 @@ func (m *Interface) createDeviceNode(path string, major int, minor int) error {
 	return unix.Chmod(path, 0666)
 }
 
+// LoadNVIDIAKernelModules loads the NVIDIA kernel modules.
+func (m *Interface) LoadNVIDIAKernelModules() error {
+	modules := []string{"nvidia", "nvidia-uvm", "nvidia-modeset"}
+
+	for _, module := range modules {
+		if m.dryRun {
+			m.logger.Infof("Running: /sbin/modprobe %s", module)
+			continue
+		}
+		cmd := exec.Command("/sbin/modprobe", module)
+
+		if output, err := cmd.CombinedOutput(); err != nil {
+			m.logger.Debugf("Failed to load kernel module %s: %v", module, string(output))
+			return fmt.Errorf("failed to load kernel module %s: %v", module, err)
+		}
+	}
+
+	return nil
+}
+
 type nvidiaDevices struct {
 	devices.Devices
 }