[PATCH v7 1/2] drm/buddy: Add start address support to trim function

[Paneer Selvam, Arunpravin]

On 7/24/2024 8:42 PM, Jani Nikula wrote:
> On Tue, 23 Jul 2024, Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com> wrote:
>> - Add a new start parameter in trim function to specify exact
>>    address from where to start the trimming. This would help us
>>    in situations like if drivers would like to do address alignment
>>    for specific requirements.
>>
>> - Add a new flag DRM_BUDDY_TRIM_DISABLE. Drivers can use this
>>    flag to disable the allocator trimming part. This patch enables
>>    the drivers control trimming and they can do it themselves
>>    based on the application requirements.
>>
>> v1:(Matthew)
>>    - check new_start alignment with min chunk_size
>>    - use range_overflows()
>>
>> Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
>> Acked-by: Alex Deucher <alexander.deucher at amd.com>
>> Acked-by: Christian König <christian.koenig at amd.com>
>> ---
>>   drivers/gpu/drm/drm_buddy.c          | 25 +++++++++++++++++++++++--
>>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c |  2 +-
>>   include/drm/drm_buddy.h              |  2 ++
>>   3 files changed, 26 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
>> index 6a8e45e9d0ec..103c185bb1c8 100644
>> --- a/drivers/gpu/drm/drm_buddy.c
>> +++ b/drivers/gpu/drm/drm_buddy.c
>> @@ -851,6 +851,7 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm,
>>    * drm_buddy_block_trim - free unused pages
>>    *
>>    * @mm: DRM buddy manager
>> + * @start: start address to begin the trimming.
>>    * @new_size: original size requested
>>    * @blocks: Input and output list of allocated blocks.
>>    * MUST contain single block as input to be trimmed.
>> @@ -866,11 +867,13 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm,
>>    * 0 on success, error code on failure.
>>    */
>>   int drm_buddy_block_trim(struct drm_buddy *mm,
>> +			 u64 *start,
> Is this a pointer only to allow passing NULL as "don't specify"? It's
> not used for returning anything in *start. Maybe it should be a const
> pointer?
>
> Not the prettiest of interfaces, and the kernel-doc does not reflect any
> of this.
We have a plan to improve the interface and add multiple block trim 
support as well.
I will modify in the follow-up patch.

Thanks,
Arun.
>
> BR,
> Jani.
>
>
>>   			 u64 new_size,
>>   			 struct list_head *blocks)
>>   {
>>   	struct drm_buddy_block *parent;
>>   	struct drm_buddy_block *block;
>> +	u64 block_start, block_end;
>>   	LIST_HEAD(dfs);
>>   	u64 new_start;
>>   	int err;
>> @@ -882,6 +885,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>   				 struct drm_buddy_block,
>>   				 link);
>>   
>> +	block_start = drm_buddy_block_offset(block);
>> +	block_end = block_start + drm_buddy_block_size(mm, block);
>> +
>>   	if (WARN_ON(!drm_buddy_block_is_allocated(block)))
>>   		return -EINVAL;
>>   
>> @@ -894,6 +900,20 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>   	if (new_size == drm_buddy_block_size(mm, block))
>>   		return 0;
>>   
>> +	new_start = block_start;
>> +	if (start) {
>> +		new_start = *start;
>> +
>> +		if (new_start < block_start)
>> +			return -EINVAL;
>> +
>> +		if (!IS_ALIGNED(new_start, mm->chunk_size))
>> +			return -EINVAL;
>> +
>> +		if (range_overflows(new_start, new_size, block_end))
>> +			return -EINVAL;
>> +	}
>> +
>>   	list_del(&block->link);
>>   	mark_free(mm, block);
>>   	mm->avail += drm_buddy_block_size(mm, block);
>> @@ -904,7 +924,6 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>   	parent = block->parent;
>>   	block->parent = NULL;
>>   
>> -	new_start = drm_buddy_block_offset(block);
>>   	list_add(&block->tmp_link, &dfs);
>>   	err =  __alloc_range(mm, &dfs, new_start, new_size, blocks, NULL);
>>   	if (err) {
>> @@ -1066,7 +1085,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>   	} while (1);
>>   
>>   	/* Trim the allocated block to the required size */
>> -	if (original_size != size) {
>> +	if (!(flags & DRM_BUDDY_TRIM_DISABLE) &&
>> +	    original_size != size) {
>>   		struct list_head *trim_list;
>>   		LIST_HEAD(temp);
>>   		u64 trim_size;
>> @@ -1083,6 +1103,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>   		}
>>   
>>   		drm_buddy_block_trim(mm,
>> +				     NULL,
>>   				     trim_size,
>>   				     trim_list);
>>   
>> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>> index fe3779fdba2c..423b261ea743 100644
>> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>> @@ -150,7 +150,7 @@ static int xe_ttm_vram_mgr_new(struct ttm_resource_manager *man,
>>   	} while (remaining_size);
>>   
>>   	if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
>> -		if (!drm_buddy_block_trim(mm, vres->base.size, &vres->blocks))
>> +		if (!drm_buddy_block_trim(mm, NULL, vres->base.size, &vres->blocks))
>>   			size = vres->base.size;
>>   	}
>>   
>> diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
>> index 2a74fa9d0ce5..9689a7c5dd36 100644
>> --- a/include/drm/drm_buddy.h
>> +++ b/include/drm/drm_buddy.h
>> @@ -27,6 +27,7 @@
>>   #define DRM_BUDDY_CONTIGUOUS_ALLOCATION		BIT(2)
>>   #define DRM_BUDDY_CLEAR_ALLOCATION		BIT(3)
>>   #define DRM_BUDDY_CLEARED			BIT(4)
>> +#define DRM_BUDDY_TRIM_DISABLE			BIT(5)
>>   
>>   struct drm_buddy_block {
>>   #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
>> @@ -155,6 +156,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>   			   unsigned long flags);
>>   
>>   int drm_buddy_block_trim(struct drm_buddy *mm,
>> +			 u64 *start,
>>   			 u64 new_size,
>>   			 struct list_head *blocks);
>>   
>>
>> base-commit: b27d70e1042bf6a31ba7e5acf58b61c9cd28f95b