[PATCH v11 5/5] drm/amdgpu: add drm buddy support to amdgpu
Christian König
ckoenig.leichtzumerken at gmail.com
Fri Feb 4 13:23:58 UTC 2022
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.
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.
Regards,
Christian.
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