On Thu, Mar 16, 2017 at 10:55:06AM +0000, Chris Wilson wrote:
> guc_addon_create() makes the assumption that it need only kmap the
> initial page in order to write all of the configuration data used by the
> guc. Confusingly it also allocates many scratch pages in the same vma
> and passes that to the guc. Reassure the reader that all is well with a
> BUILD_BUG_ON() that we do not access outside of the kmapped page.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_guc_submission.c | 5 +++++
> drivers/gpu/drm/i915/i915_utils.h | 1 +
> 2 files changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
> index 97726fcb1230..91d7ab0df0cd 100644
> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
> @@ -888,13 +888,16 @@ static void guc_addon_create(struct intel_guc *guc)
> guc->ads_vma = vma;
> }
>
> + /* First members are assumed to be in a single page */
s/First/Written/
> page = i915_vma_first_page(vma);
> blob = kmap(page);
>
> /* GuC scheduling policies */
> + BUILD_BUG_ON(ptr_offset_end(blob, policies) > PAGE_SIZE);
> guc_policies_init(&blob->policies);
>
> /* MMIO reg state */
> + BUILD_BUG_ON(ptr_offset_end(blob, reg_state) > PAGE_SIZE);
> for_each_engine(engine, dev_priv, id) {
> blob->reg_state.mmio_white_list[engine->guc_id].mmio_start =
> engine->mmio_base + GUC_MMIO_WHITE_LIST_START;
> @@ -903,6 +906,8 @@ static void guc_addon_create(struct intel_guc *guc)
> blob->reg_state.mmio_white_list[engine->guc_id].count = 0;
> }
>
> + BUILD_BUG_ON(ptr_offset_end(blob, reg_state) > PAGE_SIZE);
> +
> /*
> * The GuC requires a "Golden Context" when it reinitialises
> * engines after a reset. Here we use the Render ring default
--
Chris Wilson, Intel Open Source Technology Centre
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