On 5/20/2026 3:52 PM, Upadhyay, Tejas wrote:
-----Original Message-----
From: Arunpravin Paneer Selvam <[email protected]>
Sent: 20 May 2026 14:24
To: Upadhyay, Tejas <[email protected]>; intel-
[email protected]
Cc: Auld, Matthew <[email protected]>; Brost, Matthew
<[email protected]>; [email protected]; Ghimiray,
Himal Prasad <[email protected]>; dri-
[email protected]
Subject: Re: [PATCH V10 03/10] drm/gpu: Add
gpu_buddy_allocated_addr_to_block helper
On 5/19/2026 5:58 PM, Tejas Upadhyay wrote:
Add helper with primary purpose is to efficiently trace a specific
physical memory address back to its corresponding TTM buffer object.
v2:
-
%s/gpu_buddy_addr_to_block/gpu_buddy_allocated_addr_to_block(MattA)
- remove clear->avail and split nodes check(MattA)
- Adapt lockdep(MattB)
Signed-off-by: Tejas Upadhyay <[email protected]>
Cc: Arunpravin Paneer Selvam <[email protected]>
Cc: [email protected]
---
drivers/gpu/buddy.c | 53
+++++++++++++++++++++++++++++++++++++++
include/linux/gpu_buddy.h | 2 ++
2 files changed, 55 insertions(+)
diff --git a/drivers/gpu/buddy.c b/drivers/gpu/buddy.c index
eb1457376307..9de9872294a6 100644
--- a/drivers/gpu/buddy.c
+++ b/drivers/gpu/buddy.c
@@ -594,6 +594,59 @@ void gpu_buddy_free_block(struct gpu_buddy
*mm,
}
EXPORT_SYMBOL(gpu_buddy_free_block);
+/**
+ * gpu_buddy_allocated_addr_to_block - given relative address find
+the allocated block
+ *
+ * @mm: GPU buddy manager
+ * @addr: Relative address
+ *
+ * Returns:
+ * gpu_buddy_block on success, NULL or error code on failure */
+struct gpu_buddy_block *gpu_buddy_allocated_addr_to_block(struct
+gpu_buddy *mm, u64 addr) {
+ struct gpu_buddy_block *block;
+ LIST_HEAD(dfs);
+ u64 end;
+ int i;
+
+ gpu_buddy_driver_lock_held(mm);
+
+ end = addr + SZ_4K - 1;
The lookup range is defined using SZ_4K, while the allocator itself
operates in units of chunk_size.
This works when chunk_size == 4K, but it creates a mismatch if the
allocator is configured differently (e.g. larger chunk sizes).
Should this helper be tied to allocator granularity (i.e. use
mm->chunk_size) instead?
Regards,
Arun.
+ for (i = 0; i < mm->n_roots; ++i)
+ list_add_tail(&mm->roots[i]->tmp_link, &dfs);
+
+ do {
+ u64 block_start;
+ u64 block_end;
+
+ block = list_first_entry_or_null(&dfs,
+ struct gpu_buddy_block,
+ tmp_link);
+ if (!block)
+ break;
+
+ list_del(&block->tmp_link);
+
+ block_start = gpu_buddy_block_offset(block);
+ block_end = block_start + gpu_buddy_block_size(mm, block) -
1;
+
+ if (!overlaps(addr, end, block_start, block_end))
+ continue;
+
+ if (gpu_buddy_block_is_allocated(block))
+ return block;
+ else if (gpu_buddy_block_is_free(block))
+ return NULL;
+
+ list_add(&block->right->tmp_link, &dfs);
+ list_add(&block->left->tmp_link, &dfs);
+ } while (1);
+
+ return ERR_PTR(-ENXIO);
+}
+EXPORT_SYMBOL(gpu_buddy_allocated_addr_to_block);
+
static void __gpu_buddy_free_list(struct gpu_buddy *mm,
struct list_head *objects,
bool mark_clear,
diff --git a/include/linux/gpu_buddy.h b/include/linux/gpu_buddy.h
index 71941a039648..e7e22fa05ee2 100644
--- a/include/linux/gpu_buddy.h
+++ b/include/linux/gpu_buddy.h
@@ -272,6 +272,8 @@ void gpu_buddy_reset_clear(struct gpu_buddy
*mm,
bool is_clear);
void gpu_buddy_free_block(struct gpu_buddy *mm, struct
gpu_buddy_block *block);
+struct gpu_buddy_block *gpu_buddy_allocated_addr_to_block(struct
+gpu_buddy *mm, u64 addr);
Could you please clarify where we plan to use this helper function in the code
path? I do not see any callers added in the current patch series.
Sure, it is getting called in API xe_ttm_vram_reserve_page_at_addr() at
https://patchwork.freedesktop.org/patch/726252/?series=161473&rev=10
Tejas
Regards,
Arun.
+
void gpu_buddy_free_list(struct gpu_buddy *mm,
struct list_head *objects,
unsigned int flags);
