convert: fix boot order for multi-OS Windows guests

convert/convert.ml

@@ -394,11 +394,25 @@ and get_target_firmware i_firmware guestcaps source output =
 
 and get_target_boot_device g inspect =
   with_return (fun {return} ->
-    (* We only do it for Linux, as most likely Windows never(?) boots
-     * from any drive other than C:.  We can revisit this decision
-     * if someone reports a bug.
+    (* For non-Linux (eg. Windows) guests, use the root filesystem
+     * device to determine which disk is the boot device.
+     * This handles multi-OS guests where the selected OS may not
+     * be on the first disk.
      *)
-    if inspect.i_type <> "linux" then return None;
+    if inspect.i_type <> "linux" then (
+      let boot_device =
+        try
+          let dev = g#part_to_dev inspect.i_root in
+          debug "get_target_boot_device: root %s is on device %s"
+            inspect.i_root dev;
+          Some (g#device_index dev)
+        with
+        | G.Error msg
+             when String.find msg "device name is not a partition" >= 0
+               || String.find msg "device not found" >= 0 ->
+           None in
+      return boot_device
+    );
 
     (* Look for "GRUB" signature in the boot sector of each disk.
      * If we find it, choose that disk.

test-data/phony-guests/Makefile.am

@@ -30,6 +30,7 @@ EXTRA_DIST = \
 	archlinux-package \
 	make-coreos-img.sh \
 	make-windows-img.sh \
+	make-windows-multi-disk-img.sh \
 	win10-software.reg \
 	win10-software.reg.bin \
 	win11-software.reg \
@@ -74,7 +75,9 @@ disk_images = \
 	win2k25.img \
 	win7-32.img \
 	winxp-32.img \
-	windows.img
+	windows.img \
+	windows-multi-disk-sda.img \
+	windows-multi-disk-sdb.img
 
 # This is 'check_DATA' because we don't need it until 'make check'
 # time and we need the tools we have built in order to make it.
@@ -163,6 +166,12 @@ win2k22-uefi.img: make-windows-img.sh \
 		windows-bcd.reg.bin
 	SRCDIR=$(srcdir) $(top_builddir)/run --test ./$< $@
 
+# Make (dummy) multi-disk Windows images (for boot order testing).
+windows-multi-disk-sda.img windows-multi-disk-sdb.img: make-windows-multi-disk-img.sh \
+		win2k22-software.reg.bin \
+		windows-system.reg.bin
+	SRCDIR=$(srcdir) $(top_builddir)/run --test ./$<
+
 # This is the 'latest` windows image used by most test cases
 windows.img: win2k22.img
 	ln -f $< $@

test-data/phony-guests/guests.xml.in

@@ -322,4 +322,30 @@
     </devices>
   </domain>
 
+  <!-- Multi-disk Windows guest: blank data disk on sda,
+       Windows OS on sdb.  Used to test boot order detection. -->
+  <domain type='test'>
+    <name>windows-multi-disk</name>
+    <memory>1048576</memory>
+    <os>
+      <type>hvm</type>
+      <boot dev='hd'/>
+    </os>
+    <devices>
+      <disk type='file' device='disk'>
+        <driver name='qemu' type='raw'/>
+        <source file='@abs_builddir@/windows-multi-disk-sda.img'/>
+        <target dev='vda' bus='virtio'/>
+      </disk>
+      <disk type='file' device='disk'>
+        <driver name='qemu' type='raw'/>
+        <source file='@abs_builddir@/windows-multi-disk-sdb.img'/>
+        <target dev='vdb' bus='virtio'/>
+      </disk>
+      <video>
+        <model type='vga' vram='16384' heads='1'/>
+      </video>
+    </devices>
+  </domain>
+
 </node>

test-data/phony-guests/make-windows-multi-disk-img.sh

@@ -0,0 +1,88 @@
+#!/bin/bash -
+# libguestfs
+# Copyright (C) 2010-2025 Red Hat Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+# Make a multi-disk Windows image for testing boot order.
+# Disk 1 (sda) is a blank data disk.
+# Disk 2 (sdb) has the Windows OS on it.
+# This tests that virt-v2v correctly identifies the boot disk
+# when Windows is not on the first disk.
+
+export LANG=C
+set -e
+
+SOFTWARE_REG="$SRCDIR/win2k22-software.reg.bin"
+SYSTEM_REG="$SRCDIR/windows-system.reg.bin"
+CMD_EXE="$SRCDIR/../binaries/bin-win64.exe"
+
+# If libguestfs doesn't support ntfs-3g/ntfsprogs, just touch
+# the output files and skip.
+if ! guestfish -a /dev/null run : available "ntfs3g ntfsprogs"; then
+    touch windows-multi-disk-sda.img windows-multi-disk-sdb.img
+    exit 0
+fi
+
+# Create disk 1 (sda) - a blank data disk with a single NTFS partition.
+guestfish <<EOF
+sparse windows-multi-disk-sda.img-t 256M
+run
+
+part-init /dev/sda gpt
+part-add /dev/sda p 64 -64
+
+mkfs ntfs /dev/sda1
+
+EOF
+
+mv windows-multi-disk-sda.img-t windows-multi-disk-sda.img
+
+# Create disk 2 (sdb) - the Windows OS disk.
+guestfish <<EOF
+sparse windows-multi-disk-sdb.img-t 512M
+run
+
+# Format the disk.
+part-init /dev/sda gpt
+part-add /dev/sda p 64     524287
+part-add /dev/sda p 524288    -64
+
+# Phony boot loader filesystem.
+mkfs vfat /dev/sda1
+
+# Mark this as a BIOS boot partition.
+part_set_gpt_type /dev/sda 1 21686148-6449-6E6F-744E-656564454649
+
+# Phony root filesystem.
+mkfs ntfs /dev/sda2
+
+# Enough to fool inspection API.
+mount /dev/sda2 /
+mkdir-p /Windows/System32/Config
+mkdir-p /Windows/System32/Drivers
+mkdir-p /Windows/TEMP
+
+upload $SOFTWARE_REG /Windows/System32/Config/SOFTWARE
+upload $SYSTEM_REG /Windows/System32/Config/SYSTEM
+
+upload $CMD_EXE /Windows/System32/cmd.exe
+
+mkdir "/Program Files"
+touch /autoexec.bat
+
+EOF
+
+mv windows-multi-disk-sdb.img-t windows-multi-disk-sdb.img

tests/Makefile.am

@@ -119,6 +119,7 @@ TESTS = \
 	test-sound.sh \
 	test-virtio-win-iso.sh \
 	test-windows-conversion.sh \
+	test-windows-multi-disk-boot-order.sh \
 	test-windows-uefi-conversion.sh \
 	$(phony_windows_scripts) \
 	$(SLOW_TESTS) \
@@ -334,5 +335,6 @@ EXTRA_DIST += \
 	test-virtio-win-iso.sh \
 	test-windows-conversion.sh \
 	test-windows-conversion-ls.txt \
+	test-windows-multi-disk-boot-order.sh \
 	test-windows-uefi-conversion.sh \
 	test-windows-phony.sh

tests/test-windows-multi-disk-boot-order.sh

@@ -0,0 +1,67 @@
+#!/bin/bash -
+# libguestfs virt-v2v test script
+# Copyright (C) 2014-2025 Red Hat Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+# Test virt-v2v boot order for multi-disk Windows guests.
+#
+# Windows is installed on the second disk (sdb).  After conversion,
+# the second disk should get boot order 1 in the output XML.
+
+source ./functions.sh
+set -e
+set -x
+
+skip_if_skipped
+requires test -s ../test-data/phony-guests/windows-multi-disk-sda.img
+requires test -s ../test-data/phony-guests/windows-multi-disk-sdb.img
+
+libvirt_uri="test://$abs_top_builddir/test-data/phony-guests/guests.xml"
+
+export VIRT_TOOLS_DATA_DIR="$srcdir/../test-data/fake-virt-tools"
+export VIRTIO_WIN="$srcdir/../test-data/fake-virtio-win/drivers"
+
+d=test-windows-multi-disk-boot-order.d
+rm -rf $d
+cleanup_fn rm -r $d
+mkdir $d
+
+$VG virt-v2v --debug-gc \
+    -i libvirt -ic "$libvirt_uri" windows-multi-disk \
+    -o local -os $d \
+    --root /dev/sdb2
+
+# Test the libvirt XML metadata and disks were created.
+test -f $d/windows-multi-disk.xml
+test -f $d/windows-multi-disk-sda
+test -f $d/windows-multi-disk-sdb
+
+# Check that the second disk (sdb, the boot disk) gets boot order 1
+# and the first disk (sda, blank data) does not.
+
+xml=$d/windows-multi-disk.xml
+
+# The sda disk must NOT have boot order 1.
+if grep -A5 'windows-multi-disk-sda' "$xml" | grep -q "boot order='1'"; then
+    echo "FAIL: disk 1 (sda) should not have boot order 1"
+    exit 1
+fi
+
+# The sdb disk (Windows root) must have boot order 1.
+if ! grep -A5 'windows-multi-disk-sdb' "$xml" | grep -q "boot order='1'"; then
+    echo "FAIL: expected boot order 1 for disk 2 (sdb)"
+    exit 1
+fi