Patch "drm/amdgpu: Handle sg size limit for contiguous allocation" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/amdgpu: Handle sg size limit for contiguous allocation

to the 6.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amdgpu-handle-sg-size-limit-for-contiguous-alloc.patch
and it can be found in the queue-6.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 44ae455c202ee88897fbd58501bc553f1582ebdb
Author: Philip Yang <Philip.Yang@xxxxxxx>
Date:   Fri Apr 19 16:27:00 2024 -0400

    drm/amdgpu: Handle sg size limit for contiguous allocation
    
    [ Upstream commit b2dba064c9bdd18c7dd39066d25453af28451dbf ]
    
    Define macro AMDGPU_MAX_SG_SEGMENT_SIZE 2GB, because struct scatterlist
    length is unsigned int, and some users of it cast to a signed int, so
    every segment of sg table is limited to size 2GB maximum.
    
    For contiguous VRAM allocation, don't limit the max buddy block size in
    order to get contiguous VRAM memory. To workaround the sg table segment
    size limit, allocate multiple segments if contiguous size is bigger than
    AMDGPU_MAX_SG_SEGMENT_SIZE.
    
    Signed-off-by: Philip Yang <Philip.Yang@xxxxxxx>
    Reviewed-by: Christian König <christian.koenig@xxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index 6c30eceec896..f91cc149d06c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -31,6 +31,8 @@
 #include "amdgpu_atomfirmware.h"
 #include "atom.h"
 
+#define AMDGPU_MAX_SG_SEGMENT_SIZE	(2UL << 30)
+
 struct amdgpu_vram_reservation {
 	u64 start;
 	u64 size;
@@ -518,9 +520,7 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 		else
 			min_block_size = mgr->default_page_size;
 
-		/* Limit maximum size to 2GiB due to SG table limitations */
-		size = min(remaining_size, 2ULL << 30);
-
+		size = remaining_size;
 		if ((size >= (u64)pages_per_block << PAGE_SHIFT) &&
 		    !(size & (((u64)pages_per_block << PAGE_SHIFT) - 1)))
 			min_block_size = (u64)pages_per_block << PAGE_SHIFT;
@@ -660,7 +660,7 @@ int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
 	amdgpu_res_first(res, offset, length, &cursor);
 	while (cursor.remaining) {
 		num_entries++;
-		amdgpu_res_next(&cursor, cursor.size);
+		amdgpu_res_next(&cursor, min(cursor.size, AMDGPU_MAX_SG_SEGMENT_SIZE));
 	}
 
 	r = sg_alloc_table(*sgt, num_entries, GFP_KERNEL);
@@ -680,7 +680,7 @@ int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
 	amdgpu_res_first(res, offset, length, &cursor);
 	for_each_sgtable_sg((*sgt), sg, i) {
 		phys_addr_t phys = cursor.start + adev->gmc.aper_base;
-		size_t size = cursor.size;
+		unsigned long size = min(cursor.size, AMDGPU_MAX_SG_SEGMENT_SIZE);
 		dma_addr_t addr;
 
 		addr = dma_map_resource(dev, phys, size, dir,
@@ -693,7 +693,7 @@ int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
 		sg_dma_address(sg) = addr;
 		sg_dma_len(sg) = size;
 
-		amdgpu_res_next(&cursor, cursor.size);
+		amdgpu_res_next(&cursor, size);
 	}
 
 	return 0;