Add optional loading of UEFI firmware via -bios parameter in QEMU

Limiting this to X8664 arch as there is no information if this works for
other architectures. This allows to load UEFI firmware on Windows hosts,
where pflash can't be used in combination with WHPX acceleration.
Default to false on non-Windows hosts and true on Windows (to have
working default).

Signed-off-by: Arthur Sengileyev <[email protected]>

Author: arixmkii

pkg/qemu/qemu.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"io/fs"
 	"os"
 	"os/exec"
@@ -598,36 +599,89 @@ func Cmdline(ctx context.Context, cfg Config) (exe string, args []string, err er
 	}
 	if !legacyBIOS {
 		var firmware string
+		firmwareInBios := runtime.GOOS == "windows"
+		if envVar := os.Getenv("LIMA_QEMU_UEFI_IN_BIOS"); envVar != "" {
+			b, err := strconv.ParseBool(os.Getenv("LIMA_QEMU_UEFI_IN_BIOS"))
+			if err != nil {
+				logrus.WithError(err).Warnf("invalid LIMA_QEMU_UEFI_IN_BIOS value %q", envVar)
+			} else {
+				firmwareInBios = b
+			}
+		}
+		firmwareInBios = firmwareInBios && *y.Arch == limayaml.X8664
 		downloadedFirmware := filepath.Join(cfg.InstanceDir, filenames.QemuEfiCodeFD)
-		if _, stErr := os.Stat(downloadedFirmware); errors.Is(stErr, os.ErrNotExist) {
-		loop:
-			for _, f := range y.Firmware.Images {
-				switch f.VMType {
-				case "", limayaml.QEMU:
-					if f.Arch == *y.Arch {
-						if _, err = fileutils.DownloadFile(ctx, downloadedFirmware, f.File, true, "UEFI code "+f.Location, *y.Arch); err != nil {
-							logrus.WithError(err).Warnf("failed to download %q", f.Location)
-							continue loop
+		firmwareWithVars := filepath.Join(cfg.InstanceDir, filenames.QemuEfiFullFD)
+		if firmwareInBios {
+			if _, stErr := os.Stat(firmwareWithVars); stErr == nil {
+				firmware = firmwareWithVars
+				logrus.Infof("Using existing firmware (%q)", firmware)
+			}
+		} else {
+			if _, stErr := os.Stat(downloadedFirmware); errors.Is(stErr, os.ErrNotExist) {
+			loop:
+				for _, f := range y.Firmware.Images {
+					switch f.VMType {
+					case "", limayaml.QEMU:
+						if f.Arch == *y.Arch {
+							if _, err = fileutils.DownloadFile(ctx, downloadedFirmware, f.File, true, "UEFI code "+f.Location, *y.Arch); err != nil {
+								logrus.WithError(err).Warnf("failed to download %q", f.Location)
+								continue loop
+							}
+							firmware = downloadedFirmware
+							logrus.Infof("Using firmware %q (downloaded from %q)", firmware, f.Location)
+							break loop
 						}
-						firmware = downloadedFirmware
-						logrus.Infof("Using firmware %q (downloaded from %q)", firmware, f.Location)
-						break loop
 					}
 				}
+			} else {
+				firmware = downloadedFirmware
+				logrus.Infof("Using existing firmware (%q)", firmware)
 			}
-		} else {
-			firmware = downloadedFirmware
-			logrus.Infof("Using existing firmware (%q)", firmware)
 		}
 		if firmware == "" {
 			firmware, err = getFirmware(exe, *y.Arch)
 			if err != nil {
 				return "", nil, err
 			}
 			logrus.Infof("Using system firmware (%q)", firmware)
+			if firmwareInBios {
+				firmwareVars, err := getFirmwareVars(exe, *y.Arch)
+				if err != nil {
+					return "", nil, err
+				}
+				logrus.Infof("Using system firmware vars (%q)", firmwareVars)
+				varsFile, err := os.Open(firmwareVars)
+				if err != nil {
+					return "", nil, err
+				}
+				defer varsFile.Close()
+				codeFile, err := os.Open(firmware)
+				if err != nil {
+					return "", nil, err
+				}
+				defer codeFile.Close()
+				resultFile, err := os.OpenFile(firmwareWithVars, os.O_CREATE|os.O_WRONLY, 0o644)
+				if err != nil {
+					return "", nil, err
+				}
+				defer resultFile.Close()
+				_, err = io.Copy(resultFile, varsFile)
+				if err != nil {
+					return "", nil, err
+				}
+				_, err = io.Copy(resultFile, codeFile)
+				if err != nil {
+					return "", nil, err
+				}
+				firmware = firmwareWithVars
+			}
 		}
 		if firmware != "" {
-			args = append(args, "-drive", fmt.Sprintf("if=pflash,format=raw,readonly=on,file=%s", firmware))
+			if firmwareInBios {
+				args = append(args, "-bios", firmware)
+			} else {
+				args = append(args, "-drive", fmt.Sprintf("if=pflash,format=raw,readonly=on,file=%s", firmware))
+			}
 		}
 	}
 
@@ -1121,9 +1175,11 @@ func getFirmware(qemuExe string, arch limayaml.Arch) (string, error) {
 	userLocalDir := filepath.Join(currentUser.HomeDir, ".local") // "$HOME/.local"
 
 	relativePath := fmt.Sprintf("share/qemu/edk2-%s-code.fd", qemuEdk2Arch(arch))
+	relativePathWin := fmt.Sprintf("share/edk2-%s-code.fd", qemuEdk2Arch(arch))
 	candidates := []string{
 		filepath.Join(userLocalDir, relativePath), // XDG-like
 		filepath.Join(localDir, relativePath),     // macOS (homebrew)
+		filepath.Join(binDir, relativePathWin),    // Windows installer
 	}
 
 	switch arch {
@@ -1165,3 +1221,40 @@ func getFirmware(qemuExe string, arch limayaml.Arch) (string, error) {
 	qemuArch := strings.TrimPrefix(filepath.Base(qemuExe), "qemu-system-")
 	return "", fmt.Errorf("could not find firmware for %q (hint: try copying the \"edk-%s-code.fd\" firmware to $HOME/.local/share/qemu/)", arch, qemuArch)
 }
+
+func getFirmwareVars(qemuExe string, arch limayaml.Arch) (string, error) {
+	var targetArch string
+	switch arch {
+	case limayaml.X8664:
+		targetArch = "i386" // vars are unified between i386 and x86_64 and normally only former is bundled
+	default:
+		return "", fmt.Errorf("unexpected architecture: %q", arch)
+	}
+
+	currentUser, err := user.Current()
+	if err != nil {
+		return "", err
+	}
+
+	binDir := filepath.Dir(qemuExe)                              // "/usr/local/bin"
+	localDir := filepath.Dir(binDir)                             // "/usr/local"
+	userLocalDir := filepath.Join(currentUser.HomeDir, ".local") // "$HOME/.local"
+
+	relativePath := fmt.Sprintf("share/qemu/edk2-%s-vars.fd", qemuEdk2Arch(targetArch))
+	relativePathWin := fmt.Sprintf("share/edk2-%s-vars.fd", qemuEdk2Arch(targetArch))
+	candidates := []string{
+		filepath.Join(userLocalDir, relativePath), // XDG-like
+		filepath.Join(localDir, relativePath),     // macOS (homebrew)
+		filepath.Join(binDir, relativePathWin),    // Windows installer
+	}
+
+	logrus.Debugf("firmware vars candidates = %v", candidates)
+
+	for _, f := range candidates {
+		if _, err := os.Stat(f); err == nil {
+			return f, nil
+		}
+	}
+
+	return "", fmt.Errorf("could not find firmware vars for %q", arch)
+}

pkg/store/filenames/filenames.go

@@ -57,6 +57,7 @@ const (
 	VzIdentifier         = "vz-identifier"
 	VzEfi                = "vz-efi"           // efi variable store
 	QemuEfiCodeFD        = "qemu-efi-code.fd" // efi code; not always created
+	QemuEfiFullFD        = "qemu-efi-full.fd" // concatenated efi vars and code; not always created
 	AnsibleInventoryYAML = "ansible-inventory.yaml"
 
 	// SocketDir is the default location for forwarded sockets with a relative paths in HostSocket.