drm/buddy: Improve contiguous memory allocation

Problem statement: The current method roundup_power_of_two()
to allocate contiguous address triggers -ENOSPC in some cases
even though we have enough free spaces and so to help with
that we introduce a try harder mechanism.

In case of -ENOSPC, the new try harder mechanism rounddown the
original size to power of 2 and iterating over the round down
sized freelist blocks to allocate the required size traversing
RHS and LHS.

As part of the above new method implementation we moved
contiguous/alignment size computation part and trim function
to the drm buddy file.

v2: Modify the alloc_range() function to return total allocated size
on -ENOSPC err and traverse RHS/LHS to allocate the required
size (Matthew).

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230909160902.15644-1-Arunpravin.PaneerSelvam@amd.com
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

drm/selftests: add drm buddy alloc range testcase

- add a test to check the range allocation
- export get_buddy() function in drm_buddy.c
- export drm_prandom_u32_max_state() in lib/drm_random.c
- include helper functions
- include prime number header file

v2:
- add drm_get_buddy() function description (Matthew Auld)
- removed unnecessary test succeeded print

Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220222174845.2175-3-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>

drm: implement a method to free unused pages

On contiguous allocation, we round up the size
to the *next* power of 2, implement a function
to free the unused pages after the newly allocate block.

v2(Matthew Auld):
- replace function name 'drm_buddy_free_unused_pages' with
drm_buddy_block_trim
- replace input argument name 'actual_size' with 'new_size'
- add more validation checks for input arguments
- add overlaps check to avoid needless searching and splitting
- merged the below patch to see the feature in action
- add free unused pages support to i915 driver
- lock drm_buddy_block_trim() function as it calls mark_free/mark_split
are all globally visible

v3(Matthew Auld):
- remove trim method error handling as we address the failure case
at drm_buddy_block_trim() function

v4:
- in case of trim, at __alloc_range() split_block failure path
marks the block as free and removes it from the original list,
potentially also freeing it, to overcome this problem, we turn
the drm_buddy_block_trim() input node into a temporary node to
prevent recursively freeing itself, but still retain the
un-splitting/freeing of the other nodes(Matthew Auld)

- modify the drm_buddy_block_trim() function return type

v5(Matthew Auld):
- revert drm_buddy_block_trim() function return type changes in v4
- modify drm_buddy_block_trim() passing argument n_pages to original_size
as n_pages has already been rounded up to the next power-of-two and
passing n_pages results noop

v6:
- fix warnings reported by kernel test robot <lkp@intel.com>

v7:
- modify drm_buddy_block_trim() function doc description
- at drm_buddy_block_trim() handle non-allocated block as
a serious programmer error
- fix a typo

Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220221164552.2434-3-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>

drm: implement top-down allocation method

Implemented a function which walk through the order list,
compares the offset and returns the maximum offset block,
this method is unpredictable in obtaining the high range
address blocks which depends on allocation and deallocation.
for instance, if driver requests address at a low specific
range, allocator traverses from the root block and splits
the larger blocks until it reaches the specific block and
in the process of splitting, lower orders in the freelist
are occupied with low range address blocks and for the
subsequent TOPDOWN memory request we may return the low
range blocks.To overcome this issue, we may go with the
below approach.

The other approach, sorting each order list entries in
ascending order and compares the last entry of each
order list in the freelist and return the max block.
This creates sorting overhead on every drm_buddy_free()
request and split up of larger blocks for a single page
request.

v2:
- Fix alignment issues(Matthew Auld)
- Remove unnecessary list_empty check(Matthew Auld)
- merged the below patch to see the feature in action
- add top-down alloc support to i915 driver

Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220221164552.2434-2-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>

drm: improve drm_buddy_alloc function

- Make drm_buddy_alloc a single function to handle
range allocation and non-range allocation demands

- Implemented a new function alloc_range() which allocates
the requested power-of-two block comply with range limitations

- Moved order computation and memory alignment logic from
i915 driver to drm buddy

v2:
merged below changes to keep the build unbroken
- drm_buddy_alloc_range() becomes obsolete and may be removed
- enable ttm range allocation (fpfn / lpfn) support in i915 driver
- apply enhanced drm_buddy_alloc() function to i915 driver

v3(Matthew Auld):
- Fix alignment issues and remove unnecessary list_empty check
- add more validation checks for input arguments
- make alloc_range() block allocations as bottom-up
- optimize order computation logic
- replace uint64_t with u64, which is preferred in the kernel

v4(Matthew Auld):
- keep drm_buddy_alloc_range() function implementation for generic
actual range allocations
- keep alloc_range() implementation for end bias allocations

v5(Matthew Auld):
- modify drm_buddy_alloc() passing argument place->lpfn to lpfn
as place->lpfn will currently always be zero for i915

v6(Matthew Auld):
- fixup potential uaf - If we are unlucky and can't allocate
enough memory when splitting blocks, where we temporarily
end up with the given block and its buddy on the respective
free list, then we need to ensure we delete both blocks,
and no just the buddy, before potentially freeing them

- fix warnings reported by kernel test robot <lkp@intel.com>

v7(Matthew Auld):
- revert fixup potential uaf
- keep __alloc_range() add node to the list logic same as
drm_buddy_alloc_blocks() by having a temporary list variable
- at drm_buddy_alloc_blocks() keep i915 range_overflows macro
and add a new check for end variable

v8:
- fix warnings reported by kernel test robot <lkp@intel.com>

v9(Matthew Auld):
- remove DRM_BUDDY_RANGE_ALLOCATION flag
- remove unnecessary function description

v10:
- keep DRM_BUDDY_RANGE_ALLOCATION flag as removing the flag
and replacing with (end < size) logic fails amdgpu driver load

Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220221164552.2434-1-Arunpravin.PaneerSelvam@amd.com

drm: move the buddy allocator from i915 into common drm

Move the base i915 buddy allocator code into drm
- Move i915_buddy.h to include/drm
- Move i915_buddy.c to drm root folder
- Rename "i915" string with "drm" string wherever applicable
- Rename "I915" string with "DRM" string wherever applicable
- Fix header file dependencies
- Fix alignment issues
- add Makefile support for drm buddy
- export functions and write kerneldoc description
- Remove i915 selftest config check condition as buddy selftest
will be moved to drm selftest folder

cleanup i915 buddy references in i915 driver module
and replace with drm buddy

v2:
- include header file in alphabetical order(Thomas)
- merged changes listed in the body section into a single patch
to keep the build intact(Christian, Jani)

v3:
- make drm buddy a separate module(Thomas, Christian)

v4:
- Fix build error reported by kernel test robot <lkp@intel.com>
- removed i915 buddy selftest from i915_mock_selftests.h to
avoid build error
- removed selftests/i915_buddy.c file as we create a new set of
buddy test cases in drm/selftests folder

v5:
- Fix merge conflict issue

v6:
- replace drm_buddy_mm structure name as drm_buddy(Thomas, Christian)
- replace drm_buddy_alloc() function name as drm_buddy_alloc_blocks()
(Thomas)
- replace drm_buddy_free() function name as drm_buddy_free_block()
(Thomas)
- export drm_buddy_free_block() function
- fix multiple instances of KMEM_CACHE() entry

v7:
- fix warnings reported by kernel test robot <lkp@intel.com>
- modify the license(Christian)

v8:
- fix warnings reported by kernel test robot <lkp@intel.com>

Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220118104504.2349-1-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>