pkg/driver/vz: Support ASIF as diffdisk

pkg/driver/krunkit/krunkit_darwin_arm64.go

@@ -14,6 +14,7 @@ import (
 	"strconv"
 
 	"github.com/docker/go-units"
+	"github.com/lima-vm/go-qcow2reader/image/raw"
 	"github.com/sirupsen/logrus"
 
 	"github.com/lima-vm/lima/v2/pkg/driver/vz"
@@ -65,7 +66,7 @@ func Cmdline(inst *limatype.Instance) (*exec.Cmd, error) {
 			}
 			extraDiskPath := filepath.Join(disk.Dir, filenames.DataDisk)
 			logrus.Infof("Mounting disk %q on %q", disk.Name, disk.MountPoint)
-			if cerr := diskUtil.ConvertToRaw(ctx, extraDiskPath, extraDiskPath, nil, true); cerr != nil {
+			if cerr := diskUtil.Convert(ctx, raw.Type, extraDiskPath, extraDiskPath, nil, true); cerr != nil {
 				return nil, fmt.Errorf("failed to convert extra disk %q to raw: %w", extraDiskPath, cerr)
 			}
 			args = append(args, "--device", fmt.Sprintf("virtio-blk,path=%s,format=raw", extraDiskPath))

pkg/driver/krunkit/krunkit_driver_darwin_arm64.go

@@ -17,6 +17,7 @@ import (
 	"time"
 
 	"github.com/coreos/go-semver/semver"
+	"github.com/lima-vm/go-qcow2reader/image/raw"
 	"github.com/sirupsen/logrus"
 
 	"github.com/lima-vm/lima/v2/pkg/driver"
@@ -60,7 +61,7 @@ func (l *LimaKrunkitDriver) Configure(inst *limatype.Instance) *driver.Configure
 
 func (l *LimaKrunkitDriver) CreateDisk(ctx context.Context) error {
 	// Krunkit also supports qcow2 disks but raw is faster to create and use.
-	return driverutil.EnsureDiskRaw(ctx, l.Instance)
+	return driverutil.EnsureDisk(ctx, l.Instance.Dir, *l.Instance.Config.Disk, raw.Type)
 }
 
 func (l *LimaKrunkitDriver) Start(ctx context.Context) (chan error, error) {

pkg/driver/vz/vm_darwin.go

@@ -14,6 +14,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"slices"
 	"strconv"
 	"sync"
 	"syscall"
@@ -22,6 +23,8 @@ import (
 	"github.com/coreos/go-semver/semver"
 	"github.com/docker/go-units"
 	"github.com/lima-vm/go-qcow2reader"
+	"github.com/lima-vm/go-qcow2reader/image"
+	"github.com/lima-vm/go-qcow2reader/image/asif"
 	"github.com/lima-vm/go-qcow2reader/image/raw"
 	"github.com/sirupsen/logrus"
 
@@ -451,8 +454,9 @@ func validateDiskFormat(diskPath string) error {
 	if err != nil {
 		return fmt.Errorf("failed to detect the format of %q: %w", diskPath, err)
 	}
-	if t := img.Type(); t != raw.Type {
-		return fmt.Errorf("expected the format of %q to be %q, got %q", diskPath, raw.Type, t)
+	supportedDiskTypes := []image.Type{raw.Type, asif.Type}
+	if t := img.Type(); !slices.Contains(supportedDiskTypes, t) {
+		return fmt.Errorf("expected the format of %q to be one of %v, got %q", diskPath, supportedDiskTypes, t)
 	}
 	// TODO: ensure that the disk is formatted with GPT or ISO9660
 	return nil
@@ -516,7 +520,7 @@ func attachDisks(ctx context.Context, inst *limatype.Instance, vmConfig *vz.Virt
 		// ConvertToRaw is a NOP if no conversion is needed
 		logrus.Debugf("Converting extra disk %q to a raw disk (if it is not a raw)", extraDiskPath)
 
-		if err = diskUtil.ConvertToRaw(ctx, extraDiskPath, extraDiskPath, nil, true); err != nil {
+		if err = diskUtil.Convert(ctx, raw.Type, extraDiskPath, extraDiskPath, nil, true); err != nil {
 			return fmt.Errorf("failed to convert extra disk %q to a raw disk: %w", extraDiskPath, err)
 		}
 		extraDiskPathAttachment, err := vz.NewDiskImageStorageDeviceAttachmentWithCacheAndSync(extraDiskPath, false, diskImageCachingMode, vz.DiskImageSynchronizationModeFsync)

pkg/driver/vz/vz_driver_darwin.go

@@ -17,6 +17,9 @@ import (
 
 	"github.com/Code-Hex/vz/v3"
 	"github.com/coreos/go-semver/semver"
+	"github.com/lima-vm/go-qcow2reader/image"
+	"github.com/lima-vm/go-qcow2reader/image/asif"
+	"github.com/lima-vm/go-qcow2reader/image/raw"
 	"github.com/sirupsen/logrus"
 
 	"github.com/lima-vm/lima/v2/pkg/driver"
@@ -75,11 +78,12 @@ const Enabled = true
 type LimaVzDriver struct {
 	Instance *limatype.Instance
 
-	SSHLocalPort   int
-	vSockPort      int
-	virtioPort     string
-	rosettaEnabled bool
-	rosettaBinFmt  bool
+	SSHLocalPort    int
+	vSockPort       int
+	virtioPort      string
+	rosettaEnabled  bool
+	rosettaBinFmt   bool
+	diskImageFormat image.Type
 
 	machine                    *virtualMachineWrapper
 	waitSSHLocalPortAccessible <-chan any
@@ -125,6 +129,11 @@ func (l *LimaVzDriver) Configure(inst *limatype.Instance) *driver.ConfiguredDriv
 	if vzOpts.Rosetta.BinFmt != nil {
 		l.rosettaBinFmt = *vzOpts.Rosetta.BinFmt
 	}
+	if vzOpts.DiskImageFormat != nil {
+		l.diskImageFormat = *vzOpts.DiskImageFormat
+	} else {
+		l.diskImageFormat = raw.Type
+	}
 
 	return &driver.ConfiguredDriver{
 		Driver: l,
@@ -161,6 +170,9 @@ func (l *LimaVzDriver) FillConfig(ctx context.Context, cfg *limatype.LimaYAML, _
 	if vzOpts.Rosetta.BinFmt == nil {
 		vzOpts.Rosetta.BinFmt = ptr.Of(false)
 	}
+	if vzOpts.DiskImageFormat == nil {
+		vzOpts.DiskImageFormat = ptr.Of(raw.Type)
+	}
 
 	var opts any
 	if err := limayaml.Convert(vzOpts, &opts, ""); err != nil {
@@ -286,6 +298,19 @@ func validateConfig(_ context.Context, cfg *limatype.LimaYAML) error {
 	default:
 		logrus.Warnf("field `video.display` must be \"vz\", \"default\", or \"none\" for VZ driver , got %q", videoDisplay)
 	}
+	var vzOpts limatype.VZOpts
+	if err := limayaml.Convert(cfg.VMOpts[limatype.VZ], &vzOpts, "vmOpts.vz"); err != nil {
+		logrus.WithError(err).Warnf("Couldn't convert %q", cfg.VMOpts[limatype.VZ])
+	}
+	switch *vzOpts.DiskImageFormat {
+	case raw.Type:
+	case asif.Type:
+		if macOSProductVersion.LessThan(*semver.New("26.0.0")) {
+			return fmt.Errorf("vmOpts.vz.diskImageFormat=%q requires macOS 26 or higher to run, got %q", asif.Type, macOSProductVersion)
+		}
+	default:
+		return fmt.Errorf("field `vmOpts.vz.diskImageFormat` must be %q or %q, got %q", raw.Type, asif.Type, *vzOpts.DiskImageFormat)
+	}
 	return nil
 }
 
@@ -295,7 +320,7 @@ func (l *LimaVzDriver) Create(_ context.Context) error {
 }
 
 func (l *LimaVzDriver) CreateDisk(ctx context.Context) error {
-	return driverutil.EnsureDiskRaw(ctx, l.Instance)
+	return driverutil.EnsureDisk(ctx, l.Instance.Dir, *l.Instance.Config.Disk, l.diskImageFormat)
 }
 
 func (l *LimaVzDriver) Start(ctx context.Context) (chan error, error) {

pkg/driverutil/disk.go

@@ -11,26 +11,27 @@ import (
 	"path/filepath"
 
 	"github.com/docker/go-units"
+	"github.com/lima-vm/go-qcow2reader/image"
 
 	"github.com/lima-vm/lima/v2/pkg/imgutil/proxyimgutil"
 	"github.com/lima-vm/lima/v2/pkg/iso9660util"
-	"github.com/lima-vm/lima/v2/pkg/limatype"
 	"github.com/lima-vm/lima/v2/pkg/limatype/filenames"
 )
 
-func EnsureDiskRaw(ctx context.Context, inst *limatype.Instance) error {
-	diffDisk := filepath.Join(inst.Dir, filenames.DiffDisk)
+// EnsureDisk ensures that the diff disk exists with the specified size and format.
+func EnsureDisk(ctx context.Context, instDir, diskSize string, diskImageFormat image.Type) error {
+	diffDisk := filepath.Join(instDir, filenames.DiffDisk)
 	if _, err := os.Stat(diffDisk); err == nil || !errors.Is(err, os.ErrNotExist) {
 		// disk is already ensured
 		return err
 	}
 
 	diskUtil := proxyimgutil.NewDiskUtil(ctx)
 
-	baseDisk := filepath.Join(inst.Dir, filenames.BaseDisk)
+	baseDisk := filepath.Join(instDir, filenames.BaseDisk)
 
-	diskSize, _ := units.RAMInBytes(*inst.Config.Disk)
-	if diskSize == 0 {
+	diskSizeInBytes, _ := units.RAMInBytes(diskSize)
+	if diskSizeInBytes == 0 {
 		return nil
 	}
 	isBaseDiskISO, err := iso9660util.IsISO9660(baseDisk)
@@ -51,8 +52,10 @@ func EnsureDiskRaw(ctx context.Context, inst *limatype.Instance) error {
 		}
 		return diffDiskF.Close()
 	}
-	if err = diskUtil.ConvertToRaw(ctx, baseDisk, diffDisk, &diskSize, false); err != nil {
-		return fmt.Errorf("failed to convert %q to a raw disk %q: %w", baseDisk, diffDisk, err)
+	// Check whether to use ASIF format
+
+	if err = diskUtil.Convert(ctx, diskImageFormat, baseDisk, diffDisk, &diskSizeInBytes, false); err != nil {
+		return fmt.Errorf("failed to convert %q to a disk %q: %w", baseDisk, diffDisk, err)
 	}
 	return err
 }

pkg/imgutil/manager.go

@@ -6,6 +6,8 @@ package imgutil
 import (
 	"context"
 	"os"
+
+	"github.com/lima-vm/go-qcow2reader/image"
 )
 
 // ImageDiskManager defines the common operations for disk image utilities.
@@ -16,8 +18,8 @@ type ImageDiskManager interface {
 	// ResizeDisk resizes an existing disk image to the specified size.
 	ResizeDisk(ctx context.Context, disk string, size int64) error
 
-	// ConvertToRaw converts a disk image to raw format.
-	ConvertToRaw(ctx context.Context, source, dest string, size *int64, allowSourceWithBackingFile bool) error
+	// Convert converts a disk image to the specified format.
+	Convert(ctx context.Context, imageType image.Type, source, dest string, size *int64, allowSourceWithBackingFile bool) error
 
 	// MakeSparse makes a file sparse, starting from the specified offset.
 	MakeSparse(ctx context.Context, f *os.File, offset int64) error

pkg/imgutil/nativeimgutil/asifutil/asif_darwin.go

@@ -0,0 +1,51 @@
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package asifutil
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+// NewAttachedASIF creates a new ASIF image file at the specified path with the given size
+// and attaches it, returning the attached device path and an open file handle.
+// The caller is responsible for detaching the ASIF image device when done.
+func NewAttachedASIF(path string, size int64) (string, *os.File, error) {
+	createArgs := []string{"image", "create", "blank", "--fs", "none", "--format", "ASIF", "--size", fmt.Sprintf("%d", size), path}
+	if err := exec.CommandContext(context.Background(), "diskutil", createArgs...).Run(); err != nil {
+		return "", nil, fmt.Errorf("failed to create ASIF image %q: %w", path, err)
+	}
+	attachArgs := []string{"image", "attach", "--noMount", path}
+	out, err := exec.CommandContext(context.Background(), "diskutil", attachArgs...).Output()
+	if err != nil {
+		return "", nil, fmt.Errorf("failed to attach ASIF image %q: %w", path, err)
+	}
+	devicePath := strings.TrimSpace(string(out))
+	f, err := os.OpenFile(devicePath, os.O_RDWR, 0o644)
+	if err != nil {
+		_ = DetachASIF(devicePath)
+		return "", nil, fmt.Errorf("failed to open ASIF device %q: %w", devicePath, err)
+	}
+	return devicePath, f, err
+}
+
+// DetachASIF detaches the ASIF image device at the specified path.
+func DetachASIF(devicePath string) error {
+	if output, err := exec.CommandContext(context.Background(), "hdiutil", "detach", devicePath).CombinedOutput(); err != nil {
+		return fmt.Errorf("failed to detach ASIF image %q: %w: %s", devicePath, err, output)
+	}
+	return nil
+}
+
+// ResizeASIF resizes the ASIF image at the specified path to the given size.
+func ResizeASIF(path string, size int64) error {
+	resizeArgs := []string{"image", "resize", "--size", fmt.Sprintf("%d", size), path}
+	if output, err := exec.CommandContext(context.Background(), "diskutil", resizeArgs...).CombinedOutput(); err != nil {
+		return fmt.Errorf("failed to resize ASIF image %q: %w: %s", path, err, output)
+	}
+	return nil
+}

pkg/imgutil/nativeimgutil/asifutil/asif_others.go

@@ -0,0 +1,25 @@
+//go:build !darwin
+
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package asifutil
+
+import (
+	"errors"
+	"os"
+)
+
+var ErrASIFNotSupported = errors.New("ASIF is only supported on macOS")
+
+func NewAttachedASIF(_ string, _ int64) (string, *os.File, error) {
+	return "", nil, ErrASIFNotSupported
+}
+
+func DetachASIF(_ string) error {
+	return ErrASIFNotSupported
+}
+
+func ResizeASIF(_ string, _ int64) error {
+	return ErrASIFNotSupported
+}

pkg/imgutil/nativeimgutil/fuzz_test.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/lima-vm/go-qcow2reader/image/raw"
 	"gotest.tools/v3/assert"
 )
 
@@ -17,6 +18,6 @@ func FuzzConvertToRaw(f *testing.F) {
 		destPath := filepath.Join(t.TempDir(), "dest.img")
 		err := os.WriteFile(srcPath, imgData, 0o600)
 		assert.NilError(t, err)
-		_ = convertToRaw(srcPath, destPath, &size, withBacking)
+		_ = convertTo(raw.Type, srcPath, destPath, &size, withBacking)
 	})
 }