Re: [Qemu-devel] [v2][PATCH 2/2] libxl: introduce gfx_passthru_kind

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

> This duplicates the code from above. I think this would be best done as:
>
> static int libxl__detect_gfx_passthru_kind(libxl__gc *gc, guest_config)
> {
>      if (b_info->u.hvm.gfx_passthru_kind != LIBXL_GFX_PASSTHRU_KIND_DEFAULT)
>          return 0;
>
>      if (libxl__is_igd_vga_passthru(gc, guest_config)) {
>          b_info->u.hvm.gfx_passthru_kind = LIBXL_GFX_PASSTHRU_KIND_IGD;
>          return 0;
>      }
>
>      LOG(ERROR, "Unable to detect graphics passthru kind");
>      return 1;
> }
>
> Then for the code in libxl__build_device_model_args_new:
>
>           if (libxl_defbool_val(b_info->u.hvm.gfx_passthru)) {
>               if (!libxl__detect_gfx_passthru_kind(gc, guest_config))
>                    return NULL
>               switch (b_info->u.hvm.gfx_passthru_kind) {
>               case LIBXL_GFX_PASSTHRU_KIND_IGD:
>                   machinearg = GCSPRINTF("%s,igd-passthru=on", machinearg);
>                   break;
>               default:
>                   LOG(ERROR, "unknown gfx_passthru_kind\n");
>                  return NULL;
>               }
>          }
>
> That is, a helper to try and autodetect kind if it is default and then a
> single switch entry for each kind.
>
>> +            default:
>> +                LOG(WARN, "gfx_passthru_kind is invalid so ignored.\n");
>
> Please return an error here, as I've shown above.

Looks good and thanks, but here 'guest_config' is a const so we 
shouldn't/can't reset b_info->u.hvm.gfx_passthru_kind like this,

b_info->u.hvm.gfx_passthru_kind = LIBXL_GFX_PASSTHRU_KIND_IGD;

So I tried to refactor a little bit to follow up yours,

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 8599a6a..605b17c 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -409,6 +409,23 @@ static char *dm_spice_options(libxl__gc *gc,
      return opt;
  }

+static int
+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;
+    }
+
+    LOG(ERROR, "Unable to detect graphics passthru kind");
+    return -1;
+}
+
  static char ** libxl__build_device_model_args_new(libxl__gc *gc,
                                          const char *dm, int guest_domid,
                                          const libxl_domain_config 
*guest_config,
@@ -427,7 +444,7 @@ static char ** 
libxl__build_device_model_args_new(libxl__gc *gc,
      const char *keymap = dm_keymap(guest_config);
      char *machinearg;
      flexarray_t *dm_args;
-    int i, connection, devid;
+    int i, connection, devid, gfx_passthru_kind;
      uint64_t ram_size;
      const char *path, *chardev;

@@ -710,9 +727,6 @@ static char ** 
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");
@@ -757,6 +771,20 @@ static char ** 
libxl__build_device_model_args_new(libxl__gc *gc,
                                              machinearg, max_ram_below_4g);
              }
          }
+
+        if (libxl_defbool_val(b_info->u.hvm.gfx_passthru)) {
+            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;
+            default:
+                LOG(ERROR, "unknown gfx_passthru_kind\n");
+                return NULL;
+            }
+        }
+
          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_internal.h b/tools/libxl/libxl_internal.h
>> index c97c62d..8912421 100644
>> --- a/tools/libxl/libxl_internal.h
>> +++ b/tools/libxl/libxl_internal.h
>> @@ -3632,6 +3632,11 @@ static inline void
>> libxl__update_config_vtpm(libxl__gc *gc,
>>     */
>>    void libxl__bitmap_copy_best_effort(libxl__gc *gc, libxl_bitmap *dptr,
>>                                        const libxl_bitmap *sptr);
>> +
>> +#ifdef LIBXL_HAVE_GFX_PASSTHRU_KIND
>
> No need for this ifdef.

Removed.

Thanks
Tiejun