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

[John Harrison <john.c.harrison@intel.com>]

On 7/18/2022 05:35, Tvrtko Ursulin wrote:
>
> 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?
Yes. Not sure if we have an IGT for the media watchdog. I recall writing 
something a long time back but I don't think it ever got merged due to 
push back that I don't recall right now. And no because it only affects 
DG2 onwards which is still forceprobed.

John.


>
> 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;