3 files changed, 27 insertions, 10 deletions
diff --git a/runsc/boot/controller.go b/runsc/boot/controller.go
index fd5b7cc9e..257f275f9 100644
--- a/runsc/boot/controller.go
+++ b/runsc/boot/controller.go
@@ -17,6 +17,7 @@ package boot
 import (
 	"errors"
 	"fmt"
+	"os"
 	"path"
 
 	specs "github.com/opencontainers/runtime-spec/specs-go"
@@ -287,7 +288,8 @@ func (cm *containerManager) WaitForLoader(_, _ *struct{}) error {
 
 // RestoreOpts contains options related to restoring a container's file system.
 type RestoreOpts struct {
-	// FilePayload contains the state file to be restored.
+	// FilePayload contains the state file to be restored, followed by the
+	// platform device file if necessary.
 	urpc.FilePayload
 
 	// SandboxID contains the ID of the sandbox.
@@ -300,16 +302,28 @@ type RestoreOpts struct {
 // signal to start.
 func (cm *containerManager) Restore(o *RestoreOpts, _ *struct{}) error {
 	log.Debugf("containerManager.Restore")
-	if len(o.FilePayload.Files) != 1 {
-		return fmt.Errorf("exactly one file must be provided")
+
+	var specFile, deviceFile *os.File
+	switch numFiles := len(o.FilePayload.Files); numFiles {
+	case 2:
+		// The device file is donated to the platform, so don't Close
+		// it here.
+		deviceFile = o.FilePayload.Files[1]
+		fallthrough
+	case 1:
+		specFile = o.FilePayload.Files[0]
+		defer specFile.Close()
+	case 0:
+		return fmt.Errorf("at least one file must be passed to Restore")
+	default:
+		return fmt.Errorf("at most two files may be passed to Restore")
 	}
-	defer o.FilePayload.Files[0].Close()
 
 	// Destroy the old kernel and create a new kernel.
 	cm.l.k.Pause()
 	cm.l.k.Destroy()
 
-	p, err := createPlatform(cm.l.conf)
+	p, err := createPlatform(cm.l.conf, int(deviceFile.Fd()))
 	if err != nil {
 		return fmt.Errorf("error creating platform: %v", err)
 	}
diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go
index 994b3d2e2..30d22b9c6 100644
--- a/runsc/boot/loader.go
+++ b/runsc/boot/loader.go
@@ -122,9 +122,9 @@ func init() {
 
 // New initializes a new kernel loader configured by spec.
 // New also handles setting up a kernel for restoring a container.
-func New(spec *specs.Spec, conf *Config, controllerFD int, ioFDs []int, console bool) (*Loader, error) {
+func New(spec *specs.Spec, conf *Config, controllerFD, deviceFD int, ioFDs []int, console bool) (*Loader, error) {
 	// Create kernel and platform.
-	p, err := createPlatform(conf)
+	p, err := createPlatform(conf, deviceFD)
 	if err != nil {
 		return nil, fmt.Errorf("error creating platform: %v", err)
 	}
@@ -301,14 +301,17 @@ func (l *Loader) Destroy() {
 	l.watchdog.Stop()
 }
 
-func createPlatform(conf *Config) (platform.Platform, error) {
+func createPlatform(conf *Config, deviceFD int) (platform.Platform, error) {
 	switch conf.Platform {
 	case PlatformPtrace:
 		log.Infof("Platform: ptrace")
 		return ptrace.New()
 	case PlatformKVM:
 		log.Infof("Platform: kvm")
-		return kvm.New()
+		if deviceFD < 0 {
+			return nil, fmt.Errorf("kvm device fd must be provided")
+		}
+		return kvm.New(os.NewFile(uintptr(deviceFD), "kvm device"))
 	default:
 		return nil, fmt.Errorf("invalid platform %v", conf.Platform)
 	}
diff --git a/runsc/boot/loader_test.go b/runsc/boot/loader_test.go
index d6bfe9ff1..9398292ff 100644
--- a/runsc/boot/loader_test.go
+++ b/runsc/boot/loader_test.go
@@ -101,7 +101,7 @@ func createLoader() (*Loader, func(), error) {
 		return nil, nil, err
 	}
 
-	l, err := New(spec, conf, fd, []int{sandEnd}, false)
+	l, err := New(spec, conf, fd, -1 /* device fd */, []int{sandEnd}, false)
 	if err != nil {
 		cleanup()
 		return nil, nil, err