Re: [PATCH 2/2] drm/xe/tests: Cover a large write to an unaligned bo offset

[Matthew Auld <matthew.auld@intel.com>]

On 27/10/2026 18:04, Mika Kuoppala wrote:
> Matthew Auld <matthew.auld@intel.com> writes:
> 
>> On 27/10/2026 14:52, Mika Kuoppala wrote:
>>> Write a contiguous 16M bo from offset 4 with xe_migrate_access_memory()
>>> and read it back. Aligning the vram side leaves buf mid page, so the
>>> following full chunk has to stay within MAX_PREEMPTDISABLE_TRANSFER.
>>>
>>> Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
>>
>> Do we know how long this test now takes? It is pulled into BAT I think.
>>
> 
> With BMG:
> 
> IGT-Version: 2.6-gfd2038445a (x86_64) (Linux: 7.3.0+ x86_64)
>    Using IGT_SRANDOM=1793110920 for randomisation
>    Starting subtest: xe_migrate
>    Starting dynamic subtest: xe_migrate_access_memory_kunit
>    Dynamic subtest xe_migrate_access_memory_kunit: SUCCESS (0.320s)
>    Subtest xe_migrate: SUCCESS (0.338s)

Ok, there is: https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/9663

Which hints that this was already very slow on ats (I think uses bounce 
buffer?). The sashiko report is maybe related? We could also just skip 
this on pre-xe2 going forward if that is simpler, since it is not really 
production. Up to you though.

>    
>> Reviewed-by: Matthew Auld <matthew.auld@intel.com>
> 
> Thanks,
> -Mika
> 
>>> ---
>>>    drivers/gpu/drm/xe/tests/xe_migrate.c | 50 +++++++++++++++++++++++++++
>>>    1 file changed, 50 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/xe/tests/xe_migrate.c b/drivers/gpu/drm/xe/tests/xe_migrate.c
>>> index a9ef8f2dcebb..715de366d33c 100644
>>> --- a/drivers/gpu/drm/xe/tests/xe_migrate.c
>>> +++ b/drivers/gpu/drm/xe/tests/xe_migrate.c
>>> @@ -1041,6 +1041,53 @@ static void access_memory_test_run_tile(struct xe_device *xe,
>>>    	kvfree(buf);
>>>    }
>>>    
>>> +static void access_memory_test_unaligned_large_write(struct kunit *test,
>>> +						     struct xe_tile *tile)
>>> +{
>>> +	const u32 size = SZ_16M, offset = 4;
>>> +	struct xe_bo *bo;
>>> +	u32 j;
>>> +	u8 *buf;
>>> +	int ret;
>>> +
>>> +	buf = kvmalloc(size, GFP_KERNEL);
>>> +	if (!buf) {
>>> +		KUNIT_FAIL(test, "Failed to allocate buffer\n");
>>> +		return;
>>> +	}
>>> +
>>> +	bo = xe_bo_create_pin_map_novm(tile_to_xe(tile), tile, size,
>>> +				       ttm_bo_type_kernel,
>>> +				       XE_BO_FLAG_VRAM_IF_DGFX(tile), false);
>>> +	if (IS_ERR(bo)) {
>>> +		KUNIT_FAIL(test, "Failed to create bo: %pe\n", bo);
>>> +		goto free_buf;
>>> +	}
>>> +
>>> +	for (j = 0; j < size / sizeof(u32); j++)
>>> +		((u32 *)buf)[j] = j;
>>> +
>>> +	xe_bo_lock(bo, false);
>>> +	ret = xe_migrate_access_memory(tile->migrate, bo, offset, buf,
>>> +				       size - offset, true);
>>> +	if (!ret) {
>>> +		memset(buf, 0, size);
>>> +		ret = xe_migrate_access_memory(tile->migrate, bo, offset, buf,
>>> +					       size - offset, false);
>>> +	}
>>> +	xe_bo_unlock(bo);
>>> +
>>> +	if (ret)
>>> +		KUNIT_FAIL(test, "Unaligned large write failed: %d\n", ret);
>>> +	else
>>> +		verify_access_memory_read(test, buf, 0, 0, size - offset,
>>> +					  "Unaligned large write");
>>> +
>>> +	xe_bo_unpin_map_no_vm(bo);
>>> +free_buf:
>>> +	kvfree(buf);
>>> +}
>>> +
>>>    static int access_memory_test_run_device(struct xe_device *xe)
>>>    {
>>>    	struct kunit *test = kunit_get_current_test();
>>> @@ -1059,6 +1106,9 @@ static int access_memory_test_run_device(struct xe_device *xe)
>>>    
>>>    		kunit_info(test, "Testing tile id %d (random offset)\n", id);
>>>    		access_memory_test_run_tile(xe, tile, test, true);
>>> +
>>> +		kunit_info(test, "Testing tile id %d (unaligned large write)\n", id);
>>> +		access_memory_test_unaligned_large_write(test, tile);
>>>    	}
>>>    
>>>    	return 0;