[Intel-gfx] [PATCH 3/4] drm/i915/uc: Place uC firmware in upper range of GGTT

[Chris Wilson]

Quoting Fernando Pacheco (2019-04-09 22:31:01)
> diff --git a/drivers/gpu/drm/i915/intel_huc.c b/drivers/gpu/drm/i915/intel_huc.c
> index 94c04f16a2ad..89e0b942ae86 100644
> --- a/drivers/gpu/drm/i915/intel_huc.c
> +++ b/drivers/gpu/drm/i915/intel_huc.c
> @@ -40,6 +40,59 @@ int intel_huc_init_misc(struct intel_huc *huc)
>         return 0;
>  }
>  
> +/*
> + * The HuC firmware image now sits above GUC_GGTT_TOP and this
> + * portion does not map through GTT. This means GuC cannot
> + * perform the HuC auth with the rsa signature sitting in that
> + * range. We resort to additionally perma-pinning the rsa signature
> + * below GUC_GGTT_TOP and utilizing this mapping to perform
> + * the authentication.
> + */
> +static int intel_huc_rsa_data_create(struct intel_huc *huc)
> +{
> +       struct drm_i915_private *i915 = huc_to_i915(huc);
> +       struct intel_guc *guc = &i915->guc;
> +       struct i915_vma *vma;
> +       void *vaddr;
> +
> +       vma = intel_guc_allocate_vma(guc, PAGE_SIZE);
> +       if (IS_ERR(vma))
> +               return PTR_ERR(vma);
> +

Are we not allocating an object for the dma xfer here that is then bound
to the reserved ggtt node? Why pin it again into the ggtt?
-Chris