diff --git a/0021-convert-windows-Online-all-virtio-disks-at-first-boo.patch b/0021-convert-windows-Online-all-virtio-disks-at-first-boo.patch
new file mode 100644
index 0000000..22d5ae2
--- /dev/null
+++ b/0021-convert-windows-Online-all-virtio-disks-at-first-boo.patch
@@ -0,0 +1,93 @@
+From 094592e713b0e5c3e012cdd11901b573287d14f4 Mon Sep 17 00:00:00 2001
+From: "Richard W.M. Jones" <rjones@redhat.com>
+Date: Tue, 27 Aug 2024 12:36:41 +0100
+Subject: [PATCH] convert: windows: Online all virtio disks at first boot
+
+Windows 2022 (and possibly earlier versions back to around 2019) will
+force offline any non-boot disks which change bus, apparently as a
+security mitigation.  The effect of this is that although the system
+drive (C:) is present after conversion, other drives may seem to
+disappear.
+
+Running a Powershell script to bring all disks online seems risky.
+The compromise is to bring online only virtio disks at first boot.
+
+To further reduce risk, we only do this if there are non-system disks
+(ie. > 1 disks in total), and only if we installed virtio drivers.
+
+Fixes: https://issues.redhat.com/browse/RHEL-55763
+Fixes: https://issues.redhat.com/browse/RHEL-55837
+Related: https://issues.redhat.com/browse/MTV-1299
+Related: https://bugzilla.redhat.com/show_bug.cgi?id=1662286
+Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
+Thanks: Martin Necas
+Acked-by: Martin Necas
+(cherry picked from commit cb56f6f94dc153051515fc7aa0d9ca646f5e2340)
+---
+ convert/convert_windows.ml | 39 +++++++++++++++++++++++++++++++++++++-
+ 1 file changed, 38 insertions(+), 1 deletion(-)
+
+diff --git a/convert/convert_windows.ml b/convert/convert_windows.ml
+index 52ca5bbe..352e1218 100644
+--- a/convert/convert_windows.ml
++++ b/convert/convert_windows.ml
+@@ -38,7 +38,8 @@ module G = Guestfs
+  * time the Windows VM is booted on KVM.
+  *)
+ 
+-let convert (g : G.guestfs) _ inspect i_firmware block_driver _ static_ips =
++let convert (g : G.guestfs) source inspect i_firmware
++      block_driver _ static_ips =
+   (*----------------------------------------------------------------------*)
+   (* Inspect the Windows guest. *)
+ 
+@@ -272,6 +273,8 @@ let convert (g : G.guestfs) _ inspect i_firmware block_driver _ static_ips =
+     Registry.with_hive_write g inspect.i_windows_software_hive
+                              update_software_hive;
+ 
++    configure_online_disks block_driver;
++
+     configure_network_interfaces net_driver;
+ 
+     fix_ntfs_heads ();
+@@ -668,6 +671,40 @@ let convert (g : G.guestfs) _ inspect i_firmware block_driver _ static_ips =
+        warning (f_"could not find registry key \
+                    HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion")
+ 
++  and configure_online_disks block_driver =
++    (* If there are > 1 disks, run a script which will force Windows
++     * to bring them all online.  Windows 2022 will offline non-boot disks
++     * where the bus changes as some sort of "security" mitigation.
++     * https://issues.redhat.com/browse/RHEL-55837
++     * https://issues.redhat.com/browse/MTV-1299
++     * https://bugzilla.redhat.com/show_bug.cgi?id=1662286
++     *)
++    let virtio_installed =
++      match block_driver with
++      | Inject_virtio_win.Virtio_blk | Virtio_SCSI -> true
++      | IDE -> false in
++    let more_than_one_disk = List.length source.s_disks > 1 in
++
++    if virtio_installed && more_than_one_disk then (
++      let psh_filename = "online-disks" in
++      let psh = ref [] in
++      let add = List.push_back psh in
++
++      add "# Uncomment this line for lots of debug output.";
++      add "# Set-PSDebug -Trace 1";
++      add "";
++      add "Write-Host \"Online all virtio disks\"";
++      add "";
++      add "Get-Disk | Where { $_.FriendlyName -like '*VirtIO*' } | % {";
++      add "    Write-Host ('  - ' + $_.Number + ': ' + $_.FriendlyName + '(' + [math]::Round($_.Size/1GB,2) + 'GB)')";
++      add "    $_ | Set-Disk -IsOffline $false";
++      add "    $_ | Set-Disk -IsReadOnly $false";
++      add "}";
++
++      (* Install the Powershell script to run late at firstboot. *)
++      Firstboot.add_firstboot_powershell g inspect.i_root psh_filename !psh
++    )
++
+   and configure_network_interfaces net_driver =
+     (* If we were asked to force network interfaces to have particular
+      * static IP addresses then it is done here by installing a
diff --git a/virt-v2v.spec b/virt-v2v.spec
index 2a06dcc..e3a99f7 100644
--- a/virt-v2v.spec
+++ b/virt-v2v.spec
@@ -7,7 +7,7 @@
 Name:          virt-v2v
 Epoch:         1
 Version:       2.5.6
-Release:       1%{?dist}
+Release:       2%{?dist}
 Summary:       Convert a virtual machine to run on KVM
 
 License:       GPL-2.0-or-later AND LGPL-2.0-or-later
@@ -47,6 +47,7 @@ Patch0017:     0017-RHEL-tests-Remove-btrfs-test.patch
 Patch0018:     0018-RHEL-Remove-block-driver-option.patch
 Patch0019:     0019-RHEL-Remove-o-rhv-o-rhv-upload-and-o-vdsm-modes.patch
 Patch0020:     0020-RHEL-Add-warning-about-virt-v2v-in-place-not-being-s.patch
+Patch0021:     0021-convert-windows-Online-all-virtio-disks-at-first-boo.patch
 
 %if !0%{?rhel}
 # libguestfs hasn't been built on i686 for a while since there is no
@@ -334,6 +335,10 @@ done
 
 
 %changelog
+* Wed Aug 28 2024 Richard W.M. Jones <rjones@redhat.com> - 1:2.5.6-2
+- convert: windows: Online all virtio disks at first boot
+  resolves: RHEL-56318
+
 * Mon Aug 12 2024 Richard W.M. Jones <rjones@redhat.com> - 1:2.5.6-1
 - Further fixes for QEMU Guest Agent install & VMware Tools removal
   resolves: RHEL-50563