Re: [PATCH 13/20] drm/i915/ttm: mappable migration on fault

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On 1/26/22 16:21, Matthew Auld wrote:
> The end goal is to have userspace tell the kernel what buffers will
> require CPU access, however if we ever reach the CPU fault handler, and
> the current resource is not mappable, then we should attempt to migrate
> the buffer to the mappable portion of LMEM, or even system memory, if the
> allowable placements permit it.
>
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 58 ++++++++++++++++++++++---
>   1 file changed, 52 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 8376e4c3d290..7299053fb1ec 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -636,11 +636,25 @@ static void i915_ttm_swap_notify(struct ttm_buffer_object *bo)
>   		i915_ttm_purge(obj);
>   }
>   
> +static bool i915_ttm_resource_mappable(struct ttm_resource *res)
> +{
> +	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
> +
> +	if (!i915_ttm_cpu_maps_iomem(res))
> +		return true;
> +
> +	return bman_res->used_visible_size == bman_res->base.num_pages;
> +}
> +
>   static int i915_ttm_io_mem_reserve(struct ttm_device *bdev, struct ttm_resource *mem)
>   {
> +

Stray line.

Otherwise LGTM.

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>