[Libguestfs] [PATCH v2] parse_libvirt_xml: look for manual firmware in "/domain/os/loader"

[Andrey Drobyshev]

According to [1], there're different ways to specify which firmware is
to be used by a libvirt-driven VM.  Namely, there's an automatic
firmware selection, e.g.:

    ...
    <os firmware='(bios|efi)'>
    ...

and a manual one, e.g.:

    ...
    <os>
        <loader readonly='yes' type='pflash'>/usr/share/OVMF/OVMF_CODE.fd</loader>
        ...
    </os>
    ...

with the latter being a way to specify UEFI firmware.  So let's add this
search path as well when parsing source VM's libvirt xml.

[1] https://libvirt.org/formatdomain.html#bios-bootloader

Signed-off-by: Andrey Drobyshev <andrey.drobyshev at virtuozzo.com>
Originally-by: Denis Plotnikov <dplotnikov at virtuozzo.com>
---
 input/parse_libvirt_xml.ml | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/input/parse_libvirt_xml.ml b/input/parse_libvirt_xml.ml
index 1e98ce1a..0fecde33 100644
--- a/input/parse_libvirt_xml.ml
+++ b/input/parse_libvirt_xml.ml
@@ -27,6 +27,9 @@ open Xpath_helpers
 open Types
 open Utils
 
+(* Detect that "/domain/os/loader" node contains path to UEFI firmware. *)
+let loader_contains_ovmf_re = PCRE.compile "/OVMF_CODE"
+
 type disk = {
   d_format : string option;     (* Disk format from XML if known. *)
   d_type : disk_type;           (* Disk type and extra information. *)
@@ -446,12 +449,26 @@ let parse_libvirt_xml ?conn xml =
     done;
     List.rev !nics in
 
-  (* Firmware. *)
+  (* Firmware.
+   * If "/domain/os" node doesn't contain "firmware" attribute (automatic
+   * firmware), we look for the presence of "OVMF_CODE" in "/domain/os/loader"
+   * node (manual firmware).
+   * See https://libvirt.org/formatdomain.html#bios-bootloader
+   *)
   let firmware =
     match xpath_string "/domain/os/@firmware" with
     | Some "bios" -> BIOS
     | Some "efi" -> UEFI
-    | None | Some _ -> UnknownFirmware in
+    | None | Some _ -> (
+      let loader = xpath_string "/domain/os/loader" in
+        match loader with
+        | None -> UnknownFirmware
+        | _ -> (
+          let loader = Option.default "" loader in
+          if PCRE.matches loader_contains_ovmf_re loader then UEFI
+          else UnknownFirmware
+        )
+    ) in
 
   (* Check for hostdev devices. (RHBZ#1472719) *)
   let () =
-- 
2.31.1