[PATCH] libxl: Add virtio (virtio-vga) display support

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

Add "virtio" vga which uses the virtio-vga device provided by upstream QEMU.
It is VGA compatible and can be enlightened with virtio-gpu drivers which are
available since Linux 4.4 and as a part of KVM Windows drivers.

Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
---
 CHANGELOG.md                     | 1 +
 docs/man/xl.cfg.5.pod.in         | 6 +++++-
 tools/libs/light/libxl_dm.c      | 3 +++
 tools/libs/light/libxl_types.idl | 1 +
 tools/xl/xl_parse.c              | 2 ++
 5 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5f31ca08fe..88ff5b9a77 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,7 @@ The format is based on [Keep a 
Changelog](https://keepachangelog.com/en/1.0.0/)
    - Support PCI passthrough for HVM domUs when dom0 is PVH (note SR-IOV
      capability usage is not yet supported on PVH dom0).
    - Smoke tests for the FreeBSD Xen builds in Cirrus CI.
+   - Virtio-VGA display support for HVM guests
 
  - On Arm:
     - Ability to enable stack protector
diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index f0c920b39d..445064ff6e 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -2566,6 +2566,8 @@ default and minimum is 8 MB.
 For QXL vga, both the default and minimal are 128MB.
 If B<videoram> is set less than 128MB, an error will be triggered.
 
+When using virtio, this parameter is ignored.
+
 =item B<stdvga=BOOLEAN>
 
 Specifies a standard VGA card with VBE (VESA BIOS Extensions) as the
@@ -2579,7 +2581,7 @@ B<This option is deprecated, use vga="stdvga" instead>.
 =item B<vga="STRING">
 
 Selects the emulated video card.
-Options are: B<none>, B<stdvga>, B<cirrus> and B<qxl>.
+Options are: B<none>, B<stdvga>, B<cirrus>, B<qxl> and B<virtio>.
 The default is B<cirrus>.
 
 In general, QXL should work with the Spice remote display protocol
@@ -2587,6 +2589,8 @@ for acceleration, and a QXL driver is necessary in the 
guest in that case.
 QXL can also work with the VNC protocol, but it will be like a standard
 VGA card without acceleration.
 
+virtio uses the VGA compatible variant of virtio-gpu.
+
 =item B<vnc=BOOLEAN>
 
 Allow access to the display via the VNC protocol.  This enables the
diff --git a/tools/libs/light/libxl_dm.c b/tools/libs/light/libxl_dm.c
index 511ec76a65..a561ba695a 100644
--- a/tools/libs/light/libxl_dm.c
+++ b/tools/libs/light/libxl_dm.c
@@ -1210,6 +1210,9 @@ static int libxl__build_device_model_args_new(libxl__gc 
*gc,
                 GCSPRINTF("qxl-vga,vram_size_mb=%"PRIu64",ram_size_mb=%"PRIu64,
                 (b_info->video_memkb/2/1024), (b_info->video_memkb/2/1024) ) );
             break;
+        case LIBXL_VGA_INTERFACE_TYPE_VIRTIO:
+            flexarray_append_pair(dm_args, "-device", "virtio-vga");
+            break;
         default:
             LOGD(ERROR, guest_domid, "Invalid emulated video card specified");
             return ERROR_INVAL;
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index a6030a2dbd..577fd6d90d 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -238,6 +238,7 @@ libxl_vga_interface_type = 
Enumeration("vga_interface_type", [
     (2, "STD"),
     (3, "NONE"),
     (4, "QXL"),
+    (5, "VIRTIO"),
     ], init_val = "LIBXL_VGA_INTERFACE_TYPE_UNKNOWN")
 
 libxl_vendor_device = Enumeration("vendor_device", [
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index 90c9386f5b..cc68d42dca 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -2833,6 +2833,8 @@ skip_usbdev:
                 b_info->u.hvm.vga.kind = LIBXL_VGA_INTERFACE_TYPE_NONE;
             } else if (!strcmp(buf, "qxl")) {
                 b_info->u.hvm.vga.kind = LIBXL_VGA_INTERFACE_TYPE_QXL;
+            } else if (!strcmp(buf, "virtio")) {
+                b_info->u.hvm.vga.kind = LIBXL_VGA_INTERFACE_TYPE_VIRTIO;
             } else {
                 fprintf(stderr, "Unknown vga \"%s\" specified\n", buf);
                 exit(1);
-- 
2.50.1



Teddy Astie | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech