Explicitly fail checkpoint/restore attempts on nvproxy FDs.

PiperOrigin-RevId: 631262290

pkg/sentry/devices/nvproxy/frontend.go

@@ -87,8 +87,7 @@ func (dev *frontendDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.D
 // frontendFD implements vfs.FileDescriptionImpl for /dev/nvidia# and
 // /dev/nvidiactl.
 //
-// frontendFD is not savable; we do not implement save/restore of host GPU
-// state.
+// +stateify savable
 type frontendFD struct {
 	vfsfd vfs.FileDescription
 	vfs.FileDescriptionDefaultImpl
@@ -101,7 +100,7 @@ type frontendFD struct {
 	memmapFile    frontendFDMemmapFile
 
 	queue           waiter.Queue
-	haveMmapContext atomic.Bool
+	haveMmapContext atomic.Bool `state:"nosave"`
 
 	// clients are handles of clients owned by this frontendFD. clients is
 	// protected by nvp.objsMu.

pkg/sentry/devices/nvproxy/frontend_mmap.go

@@ -60,6 +60,7 @@ func (fd *frontendFD) InvalidateUnsavable(ctx context.Context) error {
 	return nil
 }
 
+// +stateify savable
 type frontendFDMemmapFile struct {
 	memmap.NoBufferedIOFallback
 

pkg/sentry/devices/nvproxy/save_restore.go

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build !false
+// +build !false
+
 package nvproxy
 
 import (
@@ -19,20 +22,32 @@ import (
 	"fmt"
 )
 
-func (n *nvproxy) beforeSave() {
-	n.objsLock()
-	defer n.objsUnlock()
-	if len(n.clients) != 0 {
+// beforeSave is invoked by stateify.
+func (nvp *nvproxy) beforeSave() {
+	nvp.objsLock()
+	defer nvp.objsUnlock()
+	if len(nvp.clients) != 0 {
 		panic("can't save with live nvproxy clients")
 	}
 }
 
-func (n *nvproxy) afterLoad(goContext.Context) {
+// afterLoad is invoked by stateify.
+func (nvp *nvproxy) afterLoad(goContext.Context) {
 	Init()
-	abiCons, ok := abis[n.version]
+	abiCons, ok := abis[nvp.version]
 	if !ok {
-		panic(fmt.Sprintf("driver version %q not found in abis map", n.version))
+		panic(fmt.Sprintf("driver version %q not found in abis map", nvp.version))
 	}
-	n.abi = abiCons.cons()
-	n.objsFreeSet = make(map[*object]struct{})
+	nvp.abi = abiCons.cons()
+	nvp.objsFreeSet = make(map[*object]struct{})
+}
+
+// beforeSave is invoked by stateify.
+func (fd *frontendFD) beforeSave() {
+	panic("nvproxy.frontendFD is not saveable.")
+}
+
+// beforeSave is invoked by stateify.
+func (fd *uvmFD) beforeSave() {
+	panic("nvproxy.uvmFD is not saveable.")
 }

pkg/sentry/devices/nvproxy/uvm.go

@@ -73,7 +73,7 @@ func (dev *uvmDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry
 
 // uvmFD implements vfs.FileDescriptionImpl for /dev/nvidia-uvm.
 //
-// uvmFD is not savable; we do not implement save/restore of host GPU state.
+// +stateify savable
 type uvmFD struct {
 	vfsfd vfs.FileDescription
 	vfs.FileDescriptionDefaultImpl

pkg/sentry/devices/nvproxy/uvm_mmap.go

@@ -66,6 +66,7 @@ func (fd *uvmFD) InvalidateUnsavable(ctx context.Context) error {
 	return nil
 }
 
+// +stateify savable
 type uvmFDMemmapFile struct {
 	fd *uvmFD
 }