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drm/i915/ttm: implement access_memory

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It looks like we need this for local-memory, if we want to use ptrace.
Something more is still needed if we want to handle non-mappable memory,
which looks quite annoying.

v2:
  - ttm_bo_kmap doesn't seem to work well here, and seems to expect
    contiguous resource.
v3(Andi):
  - s/PAGE_SIZE/bytes/ when passing in the size of the mapping.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/6989
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221003172819.99245-1-matthew.auld@intel.com
This commit is contained in:
Matthew Auld 2022-10-03 18:28:19 +01:00
parent c24538f538
commit 26b15eb094
1 changed files with 45 additions and 0 deletions
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45
drivers/gpu/drm/i915/gem/i915_gem_ttm.c
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@ -699,6 +699,50 @@ static unsigned long i915_ttm_io_mem_pfn(struct ttm_buffer_object *bo,
return ((base + sg_dma_address(sg)) >> PAGE_SHIFT) + ofs;
}
static int i915_ttm_access_memory(struct ttm_buffer_object *bo,
unsigned long offset, void *buf,
int len, int write)
{
struct drm_i915_gem_object *obj = i915_ttm_to_gem(bo);
resource_size_t iomap = obj->mm.region->iomap.base -
obj->mm.region->region.start;
unsigned long page = offset >> PAGE_SHIFT;
unsigned long bytes_left = len;
/*
* TODO: For now just let it fail if the resource is non-mappable,
* otherwise we need to perform the memcpy from the gpu here, without
* interfering with the object (like moving the entire thing).
*/
if (!i915_ttm_resource_mappable(bo->resource))
return -EIO;
offset -= page << PAGE_SHIFT;
do {
unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
void __iomem *ptr;
dma_addr_t daddr;
daddr = i915_gem_object_get_dma_address(obj, page);
ptr = ioremap_wc(iomap + daddr + offset, bytes);
if (!ptr)
return -EIO;
if (write)
memcpy_toio(ptr, buf, bytes);
else
memcpy_fromio(buf, ptr, bytes);
iounmap(ptr);
page++;
buf += bytes;
bytes_left -= bytes;
offset = 0;
} while (bytes_left);
return len;
}
/*
* All callbacks need to take care not to downcast a struct ttm_buffer_object
* without checking its subclass, since it might be a TTM ghost object.
@ -715,6 +759,7 @@ static struct ttm_device_funcs i915_ttm_bo_driver = {
.delete_mem_notify = i915_ttm_delete_mem_notify,
.io_mem_reserve = i915_ttm_io_mem_reserve,
.io_mem_pfn = i915_ttm_io_mem_pfn,
.access_memory = i915_ttm_access_memory,
};
/**