[Libguestfs] [PATCH] v2v: fix UEFI bootloader for linux guests
Denis Plotnikov
dplotnikov at virtuozzo.com
Fri May 15 07:44:11 UTC 2020
Not all UEFI guests can survive conversion, because of lost bootloader
information in UEFI NVRAM. But some guest can cope with this because they
have a fallback bootloader and use UEFI Removable Media Boot Behavior.
(see https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_A_Feb14.pdf
3.5.1.1 Removable Media Boot Behavior) to load. If UEFI firmware can't find
a bootloader in its settings it uses the removable media boot behavior to
find a bootloader.
We can fix the guests which don't have such a fallback loader by providing
a temporary one. This bootloader is used for the first boot only, then the
conversion script restores the initial bootloader settings and removes the
temporary loader.
Signed-off-by: Denis Plotnikov <dplotnikov at virtuozzo.com>
---
v2v/convert_linux.ml | 15 +++++
v2v/linux_bootloaders.ml | 149 ++++++++++++++++++++++++++++++++++++++++++++--
v2v/linux_bootloaders.mli | 2 +
3 files changed, 162 insertions(+), 4 deletions(-)
diff --git a/v2v/convert_linux.ml b/v2v/convert_linux.ml
index e91ae12..77a2555 100644
--- a/v2v/convert_linux.ml
+++ b/v2v/convert_linux.ml
@@ -1122,6 +1122,21 @@ shutdown -h -P +0
Linux.augeas_reload g
);
+ (* Some linux uefi setups can't boot after conversion because of
+ lost uefi boot entries. The uefi boot entries are stored in uefi
+ NVRAM. The NVRAM content isn't a part of vm disk content and
+ usualy can't be converted with a vm. If a vm doesn't have uefi
+ fallback path (/EFI/BOOT/BOOT<arch>.efi), the vm is unbootable
+ after conversion. The following function will try to make an uefi
+ fallback path if the vm being converted is an uefi setup.
+ *)
+
+ let efi_fix_script = bootloader#fix_efi_boot () in
+
+ if efi_fix_script <> "" then
+ Firstboot.add_firstboot_script g inspect.i_root
+ "fix uefi boot" efi_fix_script;
+
(* Delete blkid caches if they exist, since they will refer to the old
* device names. blkid will rebuild these on demand.
*
diff --git a/v2v/linux_bootloaders.ml b/v2v/linux_bootloaders.ml
index de3d107..cdab7bf 100644
--- a/v2v/linux_bootloaders.ml
+++ b/v2v/linux_bootloaders.ml
@@ -36,6 +36,7 @@ class virtual bootloader = object
method virtual configure_console : unit -> unit
method virtual remove_console : unit -> unit
method update () = ()
+ method virtual fix_efi_boot : unit -> string
end
(* Helper function for SUSE: remove (hdX,X) prefix from a path. *)
@@ -43,6 +44,115 @@ let remove_hd_prefix =
let rex = PCRE.compile "^\\(hd.*\\)" in
PCRE.replace rex ""
+(* Standard uefi fallback path *)
+let uefi_fallback_path =
+ "/boot/efi/EFI/BOOT/"
+
+(* Helper function checks if 'source' contains 's' *)
+let contains source s =
+ let re = Str.regexp_string s in
+ try
+ ignore (Str.search_forward re source 0);
+ true
+ with Not_found -> false
+
+(* Helper function to get architecture suffixes for uefi files *)
+let get_uefi_arch_suffix arch =
+ let arch_suffix =
+ if contains arch "x86_64" then "X64"
+ else if contains arch "x86_32" then "X32"
+ else "" in
+ arch_suffix
+
+(* Function fixes uefi boot. It's used in both cases: legacy grub and grub2 *)
+let fix_uefi g distro distro_ver grub_config arch =
+ let cant_fix_uefi () = (
+ info (f_"Can't fix UEFI bootloader. VM may not boot.");
+ "" ) in
+
+ let file_exists file =
+ if g#exists file then
+ true
+ else (
+ info (f_"Can't find file: '%s' needed for UEFI bootloader fixing") file;
+ false ) in
+
+ let grub_path = String.sub grub_config 0 (String.rindex grub_config '/') in
+ let uefi_fallback_name =
+ let arch_suffix = get_uefi_arch_suffix arch in
+ if arch_suffix <> "" then
+ String.concat "" [uefi_fallback_path; "BOOT"; arch_suffix; ".EFI"]
+ else
+ "" in
+
+ if uefi_fallback_name = "" then (
+ info (f_"Can't determine UEFI fallback path.");
+ cant_fix_uefi () )
+ else if g#exists uefi_fallback_name then
+ (* don't do anything if uefi fallback exists *)
+ ""
+ else if uefi_fallback_name = "" then
+ cant_fix_uefi ()
+ else (
+ info (f_"Fixing UEFI bootloader.");
+ match distro, distro_ver with
+ | "centos", 6 ->
+ (* to make a bootable uefi centos 6 we need to
+ * copy grub.efi and grub.conf to UEFI fallback path
+ * and rename them to BOOT<arch>.efi and BOOT<arch>.conf
+ * correspondingly *)
+ let uefi_grub_name = String.concat "" [grub_path; "/grub.efi"] in
+ let uefi_grub_conf = String.concat "" [
+ String.sub uefi_fallback_name 0
+ (String.rindex uefi_fallback_name '.');
+ ".conf" ] in
+ if file_exists uefi_grub_name && file_exists grub_config then (
+ g#mkdir_p uefi_fallback_path;
+ g#cp uefi_grub_name uefi_fallback_name;
+ g#cp grub_config uefi_grub_conf;
+ let script = sprintf
+"#!/bin/bash
+efibootmgr -c -L \"CentOS 6\"
+rm -rf %s" uefi_fallback_path in
+ script )
+ else
+ cant_fix_uefi ()
+ | "ubuntu", 14 ->
+ (* to make a bootable uefi ubuntu 14 we need to
+ * copy shim<arch>.efi to UEFI fallback path
+ * and rename it to BOOT<arch>.efi, also we copy
+ * grub.efi and grub.cfg to UEFI fallback path without renaming *)
+ let arch_suffix =
+ String.lowercase_ascii (get_uefi_arch_suffix arch) in
+ let shim =
+ String.concat "" [grub_path; "/shim"; arch_suffix; ".efi"] in
+ let uefi_grub_name =
+ String.concat "" [grub_path; "/grub"; arch_suffix; ".efi"] in
+
+ if file_exists shim && file_exists uefi_grub_name
+ && file_exists grub_config then (
+ g#mkdir_p uefi_fallback_path;
+ g#cp shim uefi_fallback_name;
+ g#cp uefi_grub_name uefi_fallback_path;
+ g#cp grub_config uefi_fallback_path;
+ (* if the shim is at the standard path, clean up uefi fixing
+ * if not, then just don't clean up and leave the temp loader
+ * at UEFI fallback path for simplicity
+ *)
+ if contains shim "/boot/efi/EFI/ubuntu/shim" then
+ sprintf
+"#!/bin/bash
+sudo efibootmgr -c -L ubuntu -l \\\\EFI\\\\ubuntu\\\\shim%s.efi
+rm -rf %s" arch_suffix uefi_fallback_path
+ else
+ "")
+ else
+ cant_fix_uefi ()
+ | _, _ ->
+ info (f_"No UEFI fix rule for %s %d") distro distro_ver;
+ cant_fix_uefi ()
+ )
+
(* Grub1 (AKA grub-legacy) representation. *)
class bootloader_grub1 (g : G.guestfs) inspect grub_config =
let () =
@@ -60,6 +170,16 @@ class bootloader_grub1 (g : G.guestfs) inspect grub_config =
fun path -> List.mem_assoc path mounts
) [ "/boot/grub"; "/boot" ]
with Not_found -> "" in
+
+ let uefi_active =
+ match inspect.i_firmware with
+ | I_UEFI _ -> true
+ | _ -> false in
+
+ let arch = inspect.i_arch in
+ let distro = inspect.i_distro in
+ let distro_ver_major = inspect.i_major_version in
+
object
inherit bootloader
@@ -184,6 +304,12 @@ object
loop paths;
g#aug_save ()
+
+ method fix_efi_boot () =
+ if uefi_active then
+ fix_uefi g distro distro_ver_major grub_config arch
+ else
+ ""
end
(** The method used to get and set the default kernel in Grub2. *)
@@ -193,7 +319,7 @@ type default_kernel_method =
| MethodNone (** No known way. *)
(* Grub2 representation. *)
-class bootloader_grub2 (g : G.guestfs) grub_config =
+class bootloader_grub2 (g : G.guestfs) inspect grub_config =
let grub2_mkconfig_cmd =
let elems = [
@@ -221,6 +347,15 @@ class bootloader_grub2 (g : G.guestfs) grub_config =
MethodNone
) in
+ let uefi_active =
+ match inspect.i_firmware with
+ | I_UEFI _ -> true
+ | _ -> false in
+
+ let arch = inspect.i_arch in
+ let distro = inspect.i_distro in
+ let distro_ver_major = inspect.i_major_version in
+
object (self)
inherit bootloader
@@ -340,8 +475,14 @@ object (self)
method remove_console = self#grub2_update_console ~remove:true
- method update () =
- ignore (g#command [| grub2_mkconfig_cmd; "-o"; grub_config |])
+ method update () = (
+ ignore (g#command [| grub2_mkconfig_cmd; "-o"; grub_config |]))
+
+ method fix_efi_boot () =
+ if uefi_active then
+ fix_uefi g distro distro_ver_major grub_config arch
+ else
+ ""
end
(* Helper type used in detect_bootloader. *)
@@ -390,6 +531,6 @@ let detect_bootloader (g : G.guestfs) inspect =
let bl =
match typ with
| Grub1 -> new bootloader_grub1 g inspect grub_config
- | Grub2 -> new bootloader_grub2 g grub_config in
+ | Grub2 -> new bootloader_grub2 g inspect grub_config in
debug "detected bootloader %s at %s" bl#name grub_config;
bl
diff --git a/v2v/linux_bootloaders.mli b/v2v/linux_bootloaders.mli
index 30cdfe3..c4e1069 100644
--- a/v2v/linux_bootloaders.mli
+++ b/v2v/linux_bootloaders.mli
@@ -44,6 +44,8 @@ class virtual bootloader : object
(** Update the bootloader: For grub2 only this runs the
[grub2-mkconfig] command to rebuild the configuration. This
is not necessary for grub-legacy. *)
+ method virtual fix_efi_boot : unit -> string
+ (** fix UEFI bootloader and return a clean up script. *)
end
(** Encapsulates a Linux boot loader as object. *)
--
1.8.3.1
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