Re: [Intel-gfx] [PATCH 10/12] drm/i915/guc: Support larger contexts on newer hardware

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 13/07/2022 00:31, John.C.Harrison@Intel.com wrote:
> From: Matthew Brost <matthew.brost@intel.com>
> 
> The GuC needs a copy of a golden context for implementing watchdog
> resets (aka media resets). This context is larger on newer platforms.
> So adjust the size being allocated/copied accordingly.

What were the consequences of this being too small? Media watchdog reset 
broken impacting userspace? Platforms? Do we have an IGT testcase? Do we 
need a Fixes: tag? Copy stable?

Regards,

Tvrtko

> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
> index ba7541f3ca610..74cbe8eaf5318 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
> @@ -464,7 +464,11 @@ static void fill_engine_enable_masks(struct intel_gt *gt,
>   }
>   
>   #define LR_HW_CONTEXT_SIZE (80 * sizeof(u32))
> -#define LRC_SKIP_SIZE (LRC_PPHWSP_SZ * PAGE_SIZE + LR_HW_CONTEXT_SIZE)
> +#define XEHP_LR_HW_CONTEXT_SIZE (96 * sizeof(u32))
> +#define LR_HW_CONTEXT_SZ(i915) (GRAPHICS_VER_FULL(i915) >= IP_VER(12, 50) ? \
> +				    XEHP_LR_HW_CONTEXT_SIZE : \
> +				    LR_HW_CONTEXT_SIZE)
> +#define LRC_SKIP_SIZE(i915) (LRC_PPHWSP_SZ * PAGE_SIZE + LR_HW_CONTEXT_SZ(i915))
>   static int guc_prep_golden_context(struct intel_guc *guc)
>   {
>   	struct intel_gt *gt = guc_to_gt(guc);
> @@ -525,7 +529,7 @@ static int guc_prep_golden_context(struct intel_guc *guc)
>   		 * on all engines).
>   		 */
>   		ads_blob_write(guc, ads.eng_state_size[guc_class],
> -			       real_size - LRC_SKIP_SIZE);
> +			       real_size - LRC_SKIP_SIZE(gt->i915));
>   		ads_blob_write(guc, ads.golden_context_lrca[guc_class],
>   			       addr_ggtt);
>   
> @@ -599,7 +603,7 @@ static void guc_init_golden_context(struct intel_guc *guc)
>   		}
>   
>   		GEM_BUG_ON(ads_blob_read(guc, ads.eng_state_size[guc_class]) !=
> -			   real_size - LRC_SKIP_SIZE);
> +			   real_size - LRC_SKIP_SIZE(gt->i915));
>   		GEM_BUG_ON(ads_blob_read(guc, ads.golden_context_lrca[guc_class]) != addr_ggtt);
>   
>   		addr_ggtt += alloc_size;