[Intel-gfx] [PATCH] drm/i915: Verify dma_addr in gen8_ggtt_pte_encode

[Chris Wilson]

Quoting Piorkowski, Piotr (2021-02-24 15:29:25)
> From: Piotr Piórkowski <piotr.piorkowski at intel.com>
> 
> Until now, the gen8_ggtt_pte_encode function, responsible for the preparation
> of GGTT PTE, has not verified in any way whether the address given as the
> parameter is correct.
> By adding a GGTT address mask, we can easily verify that dma_addr will not fit
> in the PTE field.
> While around, cleanup a place where we hold all GEN12 GGTT PTE masks,
> and the addition of the PTE description.
> 
> Bspec: 45015
> 
> Signed-off-by: Piotr Piórkowski <piotr.piorkowski at intel.com>
> Cc: Matthew Auld <matthew.auld at intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Michal Winiarski <michal.winiarski at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_ggtt.c |  2 ++
>  drivers/gpu/drm/i915/gt/intel_gtt.h  | 13 ++++++++++++-
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> index b0b8ded834f0..52b2428da431 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> @@ -193,6 +193,8 @@ static u64 gen8_ggtt_pte_encode(dma_addr_t addr,
>  {
>         gen8_pte_t pte = addr | _PAGE_PRESENT;
>  
> +       GEM_BUG_ON(addr & ~GEN12_GGTT_PTE_ADDR_MASK);

You can also check the dma_get_mask() doesn't exceed the addr mask.
-Chris