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 <[email protected]>
Cc: Andrzej Hajda <[email protected]>
Cc: Nirmoy Das <[email protected]>
Cc: Andi Shyti <[email protected]>
---
drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 45 +++++++++++++++++++++++++
1 file changed, 45 insertions(+)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 3dc6acfcf4ec..d11cd9c57247 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -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,
};
/**
--
2.37.3
