[PATCH v11 5/5] drm/amdgpu: add drm buddy support to amdgpu
Matthew Auld
matthew.auld at intel.com
Thu Feb 10 17:52:40 UTC 2022
On 08/02/2022 11:20, Arunpravin wrote:
>
>
> On 04/02/22 6:53 pm, Christian König wrote:
>> Am 04.02.22 um 12:22 schrieb Arunpravin:
>>> On 28/01/22 7:48 pm, Matthew Auld wrote:
>>>> On Thu, 27 Jan 2022 at 14:11, Arunpravin
>>>> <Arunpravin.PaneerSelvam at amd.com> wrote:
>>>>> - Remove drm_mm references and replace with drm buddy functionalities
>>>>> - Add res cursor support for drm buddy
>>>>>
>>>>> v2(Matthew Auld):
>>>>> - replace spinlock with mutex as we call kmem_cache_zalloc
>>>>> (..., GFP_KERNEL) in drm_buddy_alloc() function
>>>>>
>>>>> - 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:
>>>>> - fix warnings reported by kernel test robot <lkp at intel.com>
>>>>>
>>>>> v5:
>>>>> - fix merge conflict issue
>>>>>
>>>>> v6:
>>>>> - fix warnings reported by kernel test robot <lkp at intel.com>
>>>>>
>>>>> Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam at amd.com>
>>>>> ---
>>>>> drivers/gpu/drm/Kconfig | 1 +
>>>>> .../gpu/drm/amd/amdgpu/amdgpu_res_cursor.h | 97 +++++--
>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 7 +-
>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 259 ++++++++++--------
>>>>> 4 files changed, 231 insertions(+), 133 deletions(-)
>>>> <snip>
>>>>
>>>>> -/**
>>>>> - * amdgpu_vram_mgr_virt_start - update virtual start address
>>>>> - *
>>>>> - * @mem: ttm_resource to update
>>>>> - * @node: just allocated node
>>>>> - *
>>>>> - * Calculate a virtual BO start address to easily check if everything is CPU
>>>>> - * accessible.
>>>>> - */
>>>>> -static void amdgpu_vram_mgr_virt_start(struct ttm_resource *mem,
>>>>> - struct drm_mm_node *node)
>>>>> -{
>>>>> - unsigned long start;
>>>>> -
>>>>> - start = node->start + node->size;
>>>>> - if (start > mem->num_pages)
>>>>> - start -= mem->num_pages;
>>>>> - else
>>>>> - start = 0;
>>>>> - mem->start = max(mem->start, start);
>>>>> -}
>>>>> -
>>>>> /**
>>>>> * amdgpu_vram_mgr_new - allocate new ranges
>>>>> *
>>>>> @@ -366,13 +357,13 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>>>>> const struct ttm_place *place,
>>>>> struct ttm_resource **res)
>>>>> {
>>>>> - unsigned long lpfn, num_nodes, pages_per_node, pages_left, pages;
>>>>> + unsigned long lpfn, pages_per_node, pages_left, pages, n_pages;
>>>>> + u64 vis_usage = 0, mem_bytes, max_bytes, min_page_size;
>>>>> struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
>>>>> struct amdgpu_device *adev = to_amdgpu_device(mgr);
>>>>> - uint64_t vis_usage = 0, mem_bytes, max_bytes;
>>>>> - struct ttm_range_mgr_node *node;
>>>>> - struct drm_mm *mm = &mgr->mm;
>>>>> - enum drm_mm_insert_mode mode;
>>>>> + struct amdgpu_vram_mgr_node *node;
>>>>> + struct drm_buddy *mm = &mgr->mm;
>>>>> + struct drm_buddy_block *block;
>>>>> unsigned i;
>>>>> int r;
>>>>>
>>>>> @@ -391,10 +382,9 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>>>>> goto error_sub;
>>>>> }
>>>>>
>>>>> - if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
>>>>> + if (place->flags & TTM_PL_FLAG_CONTIGUOUS)
>>>>> pages_per_node = ~0ul;
>>>>> - num_nodes = 1;
>>>>> - } else {
>>>>> + else {
>>>>> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>>>> pages_per_node = HPAGE_PMD_NR;
>>>>> #else
>>>>> @@ -403,11 +393,9 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>>>>> #endif
>>>>> pages_per_node = max_t(uint32_t, pages_per_node,
>>>>> tbo->page_alignment);
>>>>> - num_nodes = DIV_ROUND_UP_ULL(PFN_UP(mem_bytes), pages_per_node);
>>>>> }
>>>>>
>>>>> - node = kvmalloc(struct_size(node, mm_nodes, num_nodes),
>>>>> - GFP_KERNEL | __GFP_ZERO);
>>>>> + node = kzalloc(sizeof(*node), GFP_KERNEL);
>>>>> if (!node) {
>>>>> r = -ENOMEM;
>>>>> goto error_sub;
>>>>> @@ -415,9 +403,17 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>>>>>
>>>>> ttm_resource_init(tbo, place, &node->base);
>>>>>
>>>>> - mode = DRM_MM_INSERT_BEST;
>>>>> + INIT_LIST_HEAD(&node->blocks);
>>>>> +
>>>>> if (place->flags & TTM_PL_FLAG_TOPDOWN)
>>>>> - mode = DRM_MM_INSERT_HIGH;
>>>>> + node->flags |= DRM_BUDDY_TOPDOWN_ALLOCATION;
>>>>> +
>>>>> + if (place->fpfn || lpfn != man->size)
>>>>> + /* Allocate blocks in desired range */
>>>>> + node->flags |= DRM_BUDDY_RANGE_ALLOCATION;
>>>>> +
>>>>> + min_page_size = mgr->default_page_size;
>>>>> + BUG_ON(min_page_size < mm->chunk_size);
>>>>>
>>>>> pages_left = node->base.num_pages;
>>>>>
>>>>> @@ -425,36 +421,61 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>>>>> pages = min(pages_left, 2UL << (30 - PAGE_SHIFT));
>>>>>
>>>>> i = 0;
>>>>> - spin_lock(&mgr->lock);
>>>>> while (pages_left) {
>>>>> - uint32_t alignment = tbo->page_alignment;
>>>>> -
>>>>> if (pages >= pages_per_node)
>>>>> - alignment = pages_per_node;
>>>>> -
>>>>> - r = drm_mm_insert_node_in_range(mm, &node->mm_nodes[i], pages,
>>>>> - alignment, 0, place->fpfn,
>>>>> - lpfn, mode);
>>>>> - if (unlikely(r)) {
>>>>> - if (pages > pages_per_node) {
>>>>> - if (is_power_of_2(pages))
>>>>> - pages = pages / 2;
>>>>> - else
>>>>> - pages = rounddown_pow_of_two(pages);
>>>>> - continue;
>>>>> - }
>>>>> - goto error_free;
>>>>> + pages = pages_per_node;
>>>>> +
>>>>> + n_pages = pages;
>>>>> +
>>>>> + if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
>>>>> + n_pages = roundup_pow_of_two(n_pages);
>>>>> + min_page_size = (u64)n_pages << PAGE_SHIFT;
>>>>> +
>>>>> + if (n_pages > lpfn)
>>>>> + lpfn = n_pages;
>>>>> }
>>>>>
>>>>> - vis_usage += amdgpu_vram_mgr_vis_size(adev, &node->mm_nodes[i]);
>>>>> - amdgpu_vram_mgr_virt_start(&node->base, &node->mm_nodes[i]);
>>>>> + mutex_lock(&mgr->lock);
>>>>> + r = drm_buddy_alloc_blocks(mm, (u64)place->fpfn << PAGE_SHIFT,
>>>>> + (u64)lpfn << PAGE_SHIFT,
>>>>> + (u64)n_pages << PAGE_SHIFT,
>>>>> + min_page_size,
>>>>> + &node->blocks,
>>>>> + node->flags);
>>>>> + mutex_unlock(&mgr->lock);
>>>>> + if (unlikely(r))
>>>>> + goto error_free_blocks;
>>>>> +
>>>>> pages_left -= pages;
>>>>> ++i;
>>>>>
>>>>> if (pages > pages_left)
>>>>> pages = pages_left;
>>>>> }
>>>>> - spin_unlock(&mgr->lock);
>>>>> +
>>>>> + /* Free unused pages for contiguous allocation */
>>>>> + if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
>>>>> + u64 actual_size = (u64)node->base.num_pages << PAGE_SHIFT;
>>>>> +
>>>>> + mutex_lock(&mgr->lock);
>>>>> + drm_buddy_block_trim(mm,
>>>>> + actual_size,
>>>>> + &node->blocks);
>>>>> + mutex_unlock(&mgr->lock);
>>>>> + }
>>>>> +
>>>>> + list_for_each_entry(block, &node->blocks, link)
>>>>> + vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
>>>>> +
>>>>> + block = list_first_entry_or_null(&node->blocks,
>>>>> + struct drm_buddy_block,
>>>>> + link);
>>>>> + if (!block) {
>>>>> + r = -ENOENT;
>>>>> + goto error_free_res;
>>>>> + }
>>>>> +
>>>>> + node->base.start = amdgpu_node_start(block) >> PAGE_SHIFT;
>>>> Hmm, does this work? It looks like there are various places checking
>>>> that res->start + res->num_pages <= visible_size, which IIUC should
>>>> only return true when the entire object is placed in the mappable
>>>> portion. i915 is doing something similar. Also it looks like
>>>> ttm_resource_compat() is potentially relying on this, like when moving
>>>> something from non-mappable -> mappable in
>>>> amdgpu_bo_fault_reserve_notify()?
>>>>
>>>> Perhaps something like:
>>>>
>>>> if (vis_usage == num_pages)
>>>> base.start = 0;
>>>> else
>>>> base.start = visible_size;
>>>>
>>>> Otherwise I guess just keep amdgpu_vram_mgr_virt_start()?
>>>>
>>> hmm, I wonder how it works, may be we didn't go through the corner case
>>> where res->start + res->num_pages > visible_size
>>>
>>> in amdgpu if AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED flag is enabled, we
>>> set the ttm_place.lpfn = visible_pfn at
>>> amdgpu_bo_placement_from_domain(). Hence, in amdgpu_vram_mgr_new()
>>> function DRM_BUDDY_RANGE_ALLOCATION flag is enabled, which calls the
>>> alloc_range_bias() in drm_buddy.c.
>>>
>>> Here we get blocks chained together in random order complying
>>> visible_pfn range. say for instance num_pages = 13
>>> we may get,
>>> Block 1 addr - 500 (order-3)
>>> Block 2 addr - 400 (order-2)
>>> Block 3 addr - 600 (order-0)
>>>
>>> I think currently base.start = Block 1 start address fetched from the
>>> list and the address 500 assigned to it, which is good for the resource
>>> access since we access the blocks using the list link
>>>
>>> But for the check res->start + res->num_pages <= visible_size in few
>>> places, this doesn't work. AFAIK, keeping amdgpu_vram_mgr_virt_start()
>>> doesn't work since the function looks for nodes in continuous address to
>>> calculate the start address. AFAIK, assigning the start address (400 +
>>> num_pages <= visible_size) mislead in our case since we use linked list
>>>
>>> how about replacing the check with a bool type return function which
>>> checks the each block start address + block size <= visible_size?
>>
>> Yeah, we already have that in the TTM code. It's just not used
>> everywhere IIRC.
>
> Hi Christian,
> here we have a problem, many places in ttm and amdgpu, we are using the
> tbo->resource->start + bo->resource->num_pages operation, this doesn't
> work in case of drm buddy since it allocates blocks in different
> locations which are chained together using linked list.
AFAICT that was already the case with the existing code, since it looks
like you can get an array of discontinuous drm_mm blocks.
amdgpu_vram_mgr_virt_start() looks to be handling that by creating
fake/virtual res->start offset, which is effectively the maximum end pfn
over the range of drm_mm blocks(whilst also accounting for num_pages),
and yes if there are multiple blocks then the res->start might be more
of a "virtual" offset. AFAIK that scheme should also work as-is with the
buddy.
>>
>> The node->start can just be set to the invalid offset for now and should
>> be removed as soon as we don't need it any more.
> Assigning the start block offset to resource->start doesn't work,
> If we set node->start to invalid offset, we get an incorrect value?
>>
>> Regards,
>> Christian.
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