Am 26.01.24 um 20:47 schrieb Philip Yang:
This is to work around a bug in function drm_prime_pages_to_sg if length
of nr_pages >= 4GB, by doing the same check for max_segment and then
calling sg_alloc_table_from_pages_segment directly instead.
This issue shows up on APU because VRAM is allocated as GTT memory. It
also fixes >=4GB GTT memory mapping for mGPUs with IOMMU isolation mode.
Well that was talked about before and rejected. If we really want more
than 4GiB in DMA-bufs we need to fix drm_prime_pages_to_sg() instead.
Regards,
Christian.
Signed-off-by: Philip Yang <philip.y...@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 50 ++++++++++++++-------
1 file changed, 34 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
index 055ba2ea4c12..a203633fd629 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
@@ -171,18 +171,41 @@ static struct sg_table *amdgpu_dma_buf_map(struct
dma_buf_attachment *attach,
}
switch (bo->tbo.resource->mem_type) {
- case TTM_PL_TT:
- sgt = drm_prime_pages_to_sg(obj->dev,
- bo->tbo.ttm->pages,
- bo->tbo.ttm->num_pages);
- if (IS_ERR(sgt))
- return sgt;
-
- if (dma_map_sgtable(attach->dev, sgt, dir,
- DMA_ATTR_SKIP_CPU_SYNC))
- goto error_free;
- break;
+ case TTM_PL_TT: {
+ size_t max_segment = 0;
+ u64 num_pages;
+ int err;
+
+ sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
+ if (!sgt)
+ return ERR_PTR(-ENOMEM);
+
+ if (obj->dev)
+ max_segment = dma_max_mapping_size(obj->dev->dev);
+ if (max_segment == 0)
+ max_segment = UINT_MAX;
+
+ /*
+ * Use u64, otherwise if length of num_pages >= 4GB then size
+ * (num_pages << PAGE_SHIFT) becomes 0
+ */
+ num_pages = bo->tbo.ttm->num_pages;
+ err = sg_alloc_table_from_pages_segment(sgt, bo->tbo.ttm->pages,
+ num_pages, 0,
+ num_pages << PAGE_SHIFT,
+ max_segment,
GFP_KERNEL);
+ if (err) {
+ kfree(sgt);
+ return ERR_PTR(err);
+ }
+ if (dma_map_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC)) {
+ sg_free_table(sgt);
+ kfree(sgt);
+ return ERR_PTR(-EBUSY);
+ }
+ break;
+ }
case TTM_PL_VRAM:
r = amdgpu_vram_mgr_alloc_sgt(adev, bo->tbo.resource, 0,
bo->tbo.base.size, attach->dev,
@@ -195,11 +218,6 @@ static struct sg_table *amdgpu_dma_buf_map(struct
dma_buf_attachment *attach,
}
return sgt;
-
-error_free:
- sg_free_table(sgt);
- kfree(sgt);
- return ERR_PTR(-EBUSY);
}
/**
