[PATCH 5/5] drm/xe/query: use PAGE_SIZE as the minimum page alignment

[Mingcong Bai]

Hi Matt,

在 2025/2/26 12:43, Matthew Brost 写道:
> On Wed, Feb 26, 2025 at 10:00:22AM +0800, Mingcong Bai via B4 Relay wrote:
>> From: Mingcong Bai <jeffbai at aosc.io>
>>
>> As this component hooks into userspace API, it should be assumed that it
>> will play well with non-4K/64K pages.
>>
>> Use `PAGE_SIZE' as the final reference for page alignment instead.
>>
>> Cc: stable at vger.kernel.org
>> Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
>> Fixes: 801989b08aff ("drm/xe/uapi: Make constant comments visible in kernel doc")
>> Tested-by: Mingcong Bai <jeffbai at aosc.io>
>> Tested-by: Haien Liang <27873200 at qq.com>
>> Tested-by: Shirong Liu <lsr1024 at qq.com>
>> Tested-by: Haofeng Wu <s2600cw2 at 126.com>
>> Link: https://github.com/FanFansfan/loongson-linux/commit/22c55ab3931c32410a077b3ddb6dca3f28223360
>> Co-developed-by: Shang Yatsen <429839446 at qq.com>
>> Signed-off-by: Shang Yatsen <429839446 at qq.com>
>> Signed-off-by: Mingcong Bai <jeffbai at aosc.io>
>> ---
>>   drivers/gpu/drm/xe/xe_query.c | 2 +-
>>   include/uapi/drm/xe_drm.h     | 2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_query.c b/drivers/gpu/drm/xe/xe_query.c
>> index c059639613f7b548c168f808b7b7b354f1cf3c94..8a017c526942d1f2b401e8b9a4244e6083d7b1e5 100644
>> --- a/drivers/gpu/drm/xe/xe_query.c
>> +++ b/drivers/gpu/drm/xe/xe_query.c
>> @@ -336,7 +336,7 @@ static int query_config(struct xe_device *xe, struct drm_xe_device_query *query)
>>   		config->info[DRM_XE_QUERY_CONFIG_FLAGS] =
>>   			DRM_XE_QUERY_CONFIG_FLAG_HAS_VRAM;
>>   	config->info[DRM_XE_QUERY_CONFIG_MIN_ALIGNMENT] =
>> -		xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K;
>> +		xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : PAGE_SIZE;
> 
> We should probably assert or build a bug somewhere to ensure SZ_64K >=
> PAGE_SIZE for future-proofing. Otherwise, I think the patch makes sense.
> One more comment below.
> 
>>   	config->info[DRM_XE_QUERY_CONFIG_VA_BITS] = xe->info.va_bits;
>>   	config->info[DRM_XE_QUERY_CONFIG_MAX_EXEC_QUEUE_PRIORITY] =
>>   		xe_exec_queue_device_get_max_priority(xe);
>> diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
>> index f62689ca861a4673b885629460c11d6f3bc6523d..db7cf904926ebd6789a29d620161ac051e59f13f 100644
>> --- a/include/uapi/drm/xe_drm.h
>> +++ b/include/uapi/drm/xe_drm.h
>> @@ -394,7 +394,7 @@ struct drm_xe_query_mem_regions {
>>    *    - %DRM_XE_QUERY_CONFIG_FLAG_HAS_VRAM - Flag is set if the device
>>    *      has usable VRAM
>>    *  - %DRM_XE_QUERY_CONFIG_MIN_ALIGNMENT - Minimal memory alignment
>> - *    required by this device, typically SZ_4K or SZ_64K
>> + *    required by this device, typically PAGE_SIZE.
> 
> So I think the kernel doc needs bit more updating here, how about:
> 
> Minimal memory alignment required by this device and the CPU. The
> minimum page size for the device is usually SZ_4K or SZ_64K, while for
> the CPU, it is PAGE_SIZE. This value is calculated by
> max(min_gpu_page_size, PAGE_SIZE). This alignment is enforced on
> buffer object allocations and VM binds.

I will revise as such, taking into account other comments sent in before 
I get my next revision together. Thanks!

Best Regards,
Mingcong Bai
> 
> Again welcome others CC'd suggestion on this updated kernel doc.
> 
> Matt
> 
>>    *  - %DRM_XE_QUERY_CONFIG_VA_BITS - Maximum bits of a virtual address
>>    *  - %DRM_XE_QUERY_CONFIG_MAX_EXEC_QUEUE_PRIORITY - Value of the highest
>>    *    available exec queue priority
>>
>> -- 
>> 2.48.1
>>
>>
>