[Intel-gfx] [PATCH 17/21] drm/i915/selftests: huge page tests

[Chris Wilson]

Quoting Matthew Auld (2017-09-22 18:32:48)
> +static int igt_write_huge(struct drm_i915_gem_object *obj)
> +{
> +       struct drm_i915_private *i915 = to_i915(obj->base.dev);
> +       struct i915_gem_context *ctx = i915->kernel_context;
> +       struct i915_address_space *vm = ctx->ppgtt ? &ctx->ppgtt->base : &i915->ggtt.base;
> +       struct i915_vma *vma;
> +       unsigned int flags = PIN_USER | PIN_OFFSET_FIXED;
> +       unsigned int max_page_size;
> +       IGT_TIMEOUT(end_time);
> +       u32 max;
> +       u32 num;
> +       u64 size;
> +       int err;
> +
> +       GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
> +
> +       size = obj->base.size;
> +       if (obj->mm.page_sizes.sg & I915_GTT_PAGE_SIZE_64K)
> +               size = round_up(size, I915_GTT_PAGE_SIZE_2M);
> +
> +       max_page_size = rounddown_pow_of_two(obj->mm.page_sizes.sg);
> +       max = (vm->total - size) / max_page_size;
> +
> +       vma = i915_vma_instance(obj, vm, NULL);
> +       if (IS_ERR(vma))
> +               return PTR_ERR(vma);
> +
> +       /* Try various offsets until we timeout -- we want to avoid
> +        * issues hidden by effectively always using offset = 0.
> +        */
> +       for_each_prime_number_from(num, 0, max) {
> +               u64 offset = num * max_page_size;
> +               u32 dword;
> +
> +               err = i915_vma_unbind(vma);
> +               if (err)
> +                       goto out_vma_close;
> +
> +               err = i915_vma_pin(vma, size, max_page_size, flags | offset);
> +               if (err) {
> +                       /* The ggtt may have some pages reserved so
> +                        * refrain from erroring out.
> +                        */
> +                       if (err == -ENOSPC && i915_is_ggtt(vm))
> +                               continue;
> +
> +                       goto out_vma_close;
> +               }
> +
> +               err = igt_check_page_sizes(vma);
> +               if (err)
> +                       goto out_vma_unpin;
> +
> +               dword = offset_in_page(num) / 4;
> +
> +               err = gpu_write(vma, ctx, dword, num + 1);

We are restricting ourselves to only testing RCS. That feels like an
oversight; RCS tends to have special page table handling which may mean
we miss a bug on xCS. I would run each engine for timeout.
-Chris