[Intel-gfx] [PATCH 2/2] drm/i915: clear the gpu reloc batch

[Chris Wilson]

Quoting Matthew Auld (2020-12-24 14:34:55)
> The reloc batch is short lived but can exist in the user visible ppGTT,
> and since it's backed by an internal object, which lacks page clearing,
> we should take care to clear it upfront.
> 
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index 0cf9e79325a8..a4ecd4b4e874 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -1295,6 +1295,9 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
>                 goto err_pool;
>         }
>  
> +       memset64((void*)cmd, 0, pool->obj->base.size / sizeof(u64));

Might as well make it memset32 to avoid the cast. I'm willing to bet
it's in the noise by that point on 4096+ object.

> +       i915_gem_object_flush_map(pool->obj);

We really don't want to have to flush it twice. Remove the limit on the
flush_map before submission.
-Chris