[Qemu-devel] [v4][PATCH 2/2] libxl: introduce gfx_passthru_kind

[Tiejun Chen <tiejun.chen@intel.com>]

Although we already have 'gfx_passthru' in b_info, this doesn't suffice
after we want to handle IGD specifically. Now we define a new field of
type, gfx_passthru_kind, to indicate we're trying to pass IGD. Actually
this means we can benefit this to support other specific devices just
by extending gfx_passthru_kind. And then we can cooperate with
gfx_passthru to address IGD cases as follows:

    gfx_passthru = 0    => sets build_info.u.gfx_passthru to false
    gfx_passthru = 1    => sets build_info.u.gfx_passthru to true and
                           build_info.u.gfx_passthru_kind to DEFAULT
    gfx_passthru = "igd"    => sets build_info.u.gfx_passthru to true
                               and build_info.u.gfx_passthru_kind to IGD

Here if gfx_passthru_kind = DEFAULT, we will call
libxl__is_igd_vga_passthru() to check if we're hitting that table to need
to pass that option to qemu. But if gfx_passthru_kind = "igd" we always
force to pass that.

And "-gfx_passthru" is just introduced to work for qemu-xen-traditional
so we should get this away from libxl__build_device_model_args_new() in
the case of qemu upstream.

Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
---
 docs/man/xl.cfg.pod.5       | 35 ++++++++++++++++++++++++++++++----
 tools/libxl/libxl.h         |  6 ++++++
 tools/libxl/libxl_dm.c      | 46 +++++++++++++++++++++++++++++++++++++++++----
 tools/libxl/libxl_types.idl |  6 ++++++
 tools/libxl/xl_cmdimpl.c    | 14 ++++++++++++--
 5 files changed, 97 insertions(+), 10 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index db4a163..4aa7b05 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -812,7 +812,7 @@ through to this VM. See L<seize|/"seize_boolean"> above.
 devices passed through to this VM. See L<power_mgt|/"power_mgmt_boolean">
 above.
 
-=item B<gfx_passthru=BOOLEAN>
+=item B<gfx_passthru=BOOLEAN|"STRING">
 
 Enable graphics device PCI passthrough. This option makes an assigned
 PCI graphics card become primary graphics card in the VM. The QEMU
@@ -840,9 +840,36 @@ working graphics passthrough. See the XenVGAPassthroughTestedAdapters
 L<http://wiki.xen.org/wiki/XenVGAPassthroughTestedAdapters> wiki page
 for currently supported graphics cards for gfx_passthru.
 
-gfx_passthru is currently only supported with the qemu-xen-traditional
-device-model. Upstream qemu-xen device-model currently does not have
-support for gfx_passthru.
+gfx_passthru is currently supported both with the qemu-xen-traditional
+device-model and upstream qemu-xen device-model.
+
+When given as a boolean the B<gfx_passthru> option either disables gfx
+passthru or enables autodetection.
+
+But when given as a string the B<gfx_passthru> option describes the type
+of device to enable. Note this behavior is only supported with the upstream
+qemu-xen device-model. With qemu-xen-traditional IGD is always assumed
+and other options than autodetect or explicit IGD will result in an error.
+
+Currently, valid options are:
+
+=over 4
+
+=item B<gfx_passthru=0>
+
+Disables graphics device PCI passthrough.
+
+=item B<gfx_passthru=1>, B<gfx_passthru="default">
+
+Enables graphics device PCI passthrough and autodetects the type of device
+which is being used.
+
+=item "igd"
+
+Enables graphics device PCI passthrough but forcing the type of device to
+Intel Graphics Device.
+
+=back
 
 Note that some graphics adapters (AMD/ATI cards, for example) do not
 necessarily require gfx_passthru option, so you can use the normal Xen
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 5f9047c..899de28 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -832,6 +832,12 @@ void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, libxl_mac *src);
  */
 #define LIBXL_HAVE_SRM_V1 1
 
+/*
+ * libxl_domain_build_info has the u.hvm.gfx_passthru_kind field and
+ * the libxl_gfx_passthru_kind enumeration is defined.
+*/
+#define LIBXL_HAVE_GFX_PASSTHRU_KIND
+
 typedef char **libxl_string_list;
 void libxl_string_list_dispose(libxl_string_list *sl);
 int libxl_string_list_length(const libxl_string_list *sl);
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index b7c6592..9378b0b 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -605,7 +605,15 @@ static int libxl__build_device_model_args_old(libxl__gc *gc,
             flexarray_vappend(dm_args, "-net", "none", NULL);
         }
         if (libxl_defbool_val(b_info->u.hvm.gfx_passthru)) {
-            flexarray_append(dm_args, "-gfx_passthru");
+            switch (b_info->u.hvm.gfx_passthru_kind) {
+            case LIBXL_GFX_PASSTHRU_KIND_DEFAULT:
+            case LIBXL_GFX_PASSTHRU_KIND_IGD:
+                flexarray_append(dm_args, "-gfx_passthru");
+                break;
+            default:
+                LOG(ERROR, "unsupported gfx_passthru_kind.");
+                return ERROR_INVAL;
+            }
         }
     } else {
         if (!sdl && !vnc)
@@ -700,6 +708,22 @@ static char *dm_spice_options(libxl__gc *gc,
     return opt;
 }
 
+static enum libxl_gfx_passthru_kind
+libxl__detect_gfx_passthru_kind(libxl__gc *gc,
+                                const libxl_domain_config *guest_config)
+{
+    const libxl_domain_build_info *b_info = &guest_config->b_info;
+
+    if (b_info->u.hvm.gfx_passthru_kind != LIBXL_GFX_PASSTHRU_KIND_DEFAULT)
+        return b_info->u.hvm.gfx_passthru_kind;
+
+    if (libxl__is_igd_vga_passthru(gc, guest_config)) {
+        return LIBXL_GFX_PASSTHRU_KIND_IGD;
+    }
+
+    return LIBXL_GFX_PASSTHRU_KIND_DEFAULT;
+}
+
 static int libxl__build_device_model_args_new(libxl__gc *gc,
                                         const char *dm, int guest_domid,
                                         const libxl_domain_config *guest_config,
@@ -1031,9 +1055,6 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
             flexarray_append(dm_args, "-net");
             flexarray_append(dm_args, "none");
         }
-        if (libxl_defbool_val(b_info->u.hvm.gfx_passthru)) {
-            flexarray_append(dm_args, "-gfx_passthru");
-        }
     } else {
         if (!sdl && !vnc) {
             flexarray_append(dm_args, "-nographic");
@@ -1078,6 +1099,23 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
                                             machinearg, max_ram_below_4g);
             }
         }
+
+        if (libxl_defbool_val(b_info->u.hvm.gfx_passthru)) {
+            enum libxl_gfx_passthru_kind gfx_passthru_kind =
+                            libxl__detect_gfx_passthru_kind(gc, guest_config);
+            switch (gfx_passthru_kind) {
+            case LIBXL_GFX_PASSTHRU_KIND_IGD:
+                machinearg = GCSPRINTF("%s,igd-passthru=on", machinearg);
+                break;
+            case LIBXL_GFX_PASSTHRU_KIND_DEFAULT:
+                LOG(ERROR, "unable to detect required gfx_passthru_kind");
+                return ERROR_FAIL;
+            default:
+                LOG(ERROR, "invalid value for gfx_passthru_kind");
+                return ERROR_INVAL;
+            }
+        }
+
         flexarray_append(dm_args, machinearg);
         for (i = 0; b_info->extra_hvm && b_info->extra_hvm[i] != NULL; i++)
             flexarray_append(dm_args, b_info->extra_hvm[i]);
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 9f6ec00..7e1ab85 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -157,6 +157,11 @@ libxl_tsc_mode = Enumeration("tsc_mode", [
     (3, "native_paravirt"),
     ])
 
+libxl_gfx_passthru_kind = Enumeration("gfx_passthru_kind", [
+    (0, "default"),
+    (1, "igd"),
+    ])
+
 # Consistent with the values defined for HVM_PARAM_TIMER_MODE.
 libxl_timer_mode = Enumeration("timer_mode", [
     (-1, "unknown"),
@@ -488,6 +493,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("spice",            libxl_spice_info),
                                        
                                        ("gfx_passthru",     libxl_defbool),
+                                       ("gfx_passthru_kind", libxl_gfx_passthru_kind),
                                        
                                        ("serial",           string),
                                        ("boot",             string),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 2706759..b26fc37 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -2295,8 +2295,18 @@ skip_vfb:
         xlu_cfg_replace_string (config, "spice_streaming_video",
                                 &b_info->u.hvm.spice.streaming_video, 0);
         xlu_cfg_get_defbool(config, "nographic", &b_info->u.hvm.nographic, 0);
-        xlu_cfg_get_defbool(config, "gfx_passthru",
-                            &b_info->u.hvm.gfx_passthru, 0);
+        if (!xlu_cfg_get_long(config, "gfx_passthru", &l, 1)) {
+            libxl_defbool_set(&b_info->u.hvm.gfx_passthru, l);
+        } else if (!xlu_cfg_get_string(config, "gfx_passthru", &buf, 0)) {
+            if (libxl_gfx_passthru_kind_from_string(buf,
+                                        &b_info->u.hvm.gfx_passthru_kind)) {
+                fprintf(stderr,
+                        "ERROR: invalid value \"%s\" for \"gfx_passthru\"\n",
+                        buf);
+                exit (1);
+            }
+            libxl_defbool_set(&b_info->u.hvm.gfx_passthru, true);
+        }
         switch (xlu_cfg_get_list_as_string_list(config, "serial",
                                                 &b_info->u.hvm.serial_list,
                                                 1))
-- 
1.9.1