[Intel-gfx] [PATCH] drm/i915: Use correct huge page manager for MTL

[Matthew Auld]

On 22/02/2023 15:56, Matthew Auld wrote:
> On 22/02/2023 15:26, Jonathan Cavitt wrote:
>> MTL currently uses gen8_ppgtt_insert_huge when managing huge pages.  
>> This is because
>> MTL reports as not supporting 64K pages, or more accurately, the 
>> system that reports
>> whether a platform has 64K pages reports false for MTL.  This is only 
>> half correct,
>> as the 64K page support reporting system only cares about 64K page 
>> support for LMEM,
>> which MTL doesn't have.
>>
>> MTL should be using xehpsdv_ppgtt_insert_huge.  However, simply 
>> changing over to
>> using that manager doesn't resolve the issue because MTL is expecting 
>> the virtual
>> address space for the page table to be flushed after initialization, 
>> so we must also
>> add a flush statement there.
>>
>> The changes made to the huge page manager selection indirectly 
>> impacted some of the
>> mock hugepage selftests.  Due to the use of pte level hints, rather 
>> than pde level
>> hints, we now expect 64K page sizes to be properly reported by the 
>> GTT, so we should
>> remove the check that asserts otherwise.
>>
>> Signed-off-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
> 
> Hopefully CI will be happy now,
> Reviewed-by: Matthew Auld <matthew.auld at intel.com>

Looks it passes now, but then fails on the next subtest:
https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_114259v1/shard-apl7/igt@i915_selftest@mock@hugepages.html

Maybe it's not too outrageous to just move igt_mock_ppgtt_64K() to the 
live test section and skip running it with graphics ver >= (12, 50). 
IIUC that subtest is mostly only interesting with the old model anyway. 
I guess that test is much too HW specific to be considered good mock 
test. And maybe we should do the same for igt_mock_ppgtt_huge_fill(). 
But there we can just make the expected_gtt &= ~I915_GTT_PAGE_SIZE_64K 
conditional on graphics ver < (12, 50). Also maybe split this into two 
patches. Thoughts?

> 
>> ---
>>   drivers/gpu/drm/i915/gem/selftests/huge_pages.c | 3 ---
>>   drivers/gpu/drm/i915/gt/gen8_ppgtt.c            | 3 ++-
>>   2 files changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c 
>> b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> index defece0bcb81..1659ada4ce33 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> @@ -784,9 +784,6 @@ static int igt_mock_ppgtt_huge_fill(void *arg)
>>           GEM_BUG_ON(!expected_gtt);
>>           GEM_BUG_ON(size);
>> -        if (expected_gtt & I915_GTT_PAGE_SIZE_4K)
>> -            expected_gtt &= ~I915_GTT_PAGE_SIZE_64K;
>> -
>>           i915_vma_unpin(vma);
>>           if (vma->page_sizes.sg & I915_GTT_PAGE_SIZE_64K) {
>> diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c 
>> b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
>> index 4daaa6f55668..9c571185395f 100644
>> --- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
>> +++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
>> @@ -570,6 +570,7 @@ xehpsdv_ppgtt_insert_huge(struct 
>> i915_address_space *vm,
>>               }
>>           } while (rem >= page_size && index < max);
>> +        drm_clflush_virt_range(vaddr, PAGE_SIZE);
>>           vma_res->page_sizes_gtt |= page_size;
>>       } while (iter->sg && sg_dma_len(iter->sg));
>>   }
>> @@ -707,7 +708,7 @@ static void gen8_ppgtt_insert(struct 
>> i915_address_space *vm,
>>       struct sgt_dma iter = sgt_dma(vma_res);
>>       if (vma_res->bi.page_sizes.sg > I915_GTT_PAGE_SIZE) {
>> -        if (HAS_64K_PAGES(vm->i915))
>> +        if (GRAPHICS_VER_FULL(vm->i915) >= IP_VER(12, 50))
>>               xehpsdv_ppgtt_insert_huge(vm, vma_res, &iter, 
>> cache_level, flags);
>>           else
>>               gen8_ppgtt_insert_huge(vm, vma_res, &iter, cache_level, 
>> flags);