Re: [PATCH] drm/buddy: Add start address support to trim function

["Paneer Selvam, Arunpravin" <arunpravin.paneerselvam@amd.com>]

On 7/16/2024 3:34 PM, Matthew Auld wrote:
> On 16/07/2024 10:50, Paneer Selvam, Arunpravin wrote:
>> Hi Matthew,
>>
>> On 7/10/2024 6:20 PM, Matthew Auld wrote:
>>> On 10/07/2024 07:03, Paneer Selvam, Arunpravin wrote:
>>>> Thanks Alex.
>>>>
>>>> Hi Matthew,
>>>> Any comments?
>>>
>>> Do we not pass the required address alignment when allocating the 
>>> pages in the first place?
>> If address alignment is really useful, we can add that in the 
>> drm_buddy_alloc_blocks() function.
>
> I mean don't we already pass the min page size, which should give us 
> matching physical address alignment?
I think we don't need to align the address to the passed min_block_size 
value for all the contiguous
buffers, so I thought that decision we can leave it to the drivers and 
they can achieve that through trim function
in this kind of a specific request.

https://patchwork.freedesktop.org/series/136150/
We are getting this sparse error from the Intel CI. Do you think these 
errors are introduced with this patches?

Thanks,
Arun.
>
>>
>> Thanks,
>> Arun.
>>>
>>>>
>>>> Thanks,
>>>> Arun.
>>>>
>>>> On 7/9/2024 1:42 AM, Alex Deucher wrote:
>>>>> On Thu, Jul 4, 2024 at 4:40 AM Arunpravin Paneer Selvam
>>>>> <Arunpravin.PaneerSelvam@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@amd.com>
>>>>> Series is:
>>>>> Acked-by: Alex Deucher <alexander.deucher@amd.com>
>>>>>
>>>>> I'd like to take this series through the amdgpu tree if there are no
>>>>> objections as it's required for display buffers on some chips and I'd
>>>>> like to make sure it lands in 6.11.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Alex
>>>>>
>>>>>> ---
>>>>>>   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 94f8c34fc293..8cebe1fa4e9d 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,
>>>>>>                           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 82570f77e817..0c2f735f0265 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);
>>>>>>
>>>>>> -- 
>>>>>> 2.25.1
>>>>>>
>>>>
>>