drm/amd/amdgpu: Assign GART pages to AMD device mapping

This allows kernel mapped pages like the PDB and PTB to be
read via the iomem debugfs when there is no vram in the system.
Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c

@@ -121,6 +121,7 @@ int amdgpu_gart_table_ram_alloc(struct amdgpu_device *adev)
 	struct amdgpu_bo_param bp;
 	dma_addr_t dma_addr;
 	struct page *p;
+	unsigned long x;
 	int ret;
 
 	if (adev->gart.bo != NULL)
@@ -130,6 +131,10 @@ int amdgpu_gart_table_ram_alloc(struct amdgpu_device *adev)
 	if (!p)
 		return -ENOMEM;
 
+	/* assign pages to this device */
+	for (x = 0; x < (1UL << order); x++)
+		p[x].mapping = adev->mman.bdev.dev_mapping;
+
 	/* If the hardware does not support UTCL2 snooping of the CPU caches
 	 * then set_memory_wc() could be used as a workaround to mark the pages
 	 * as write combine memory.
@@ -223,6 +228,7 @@ void amdgpu_gart_table_ram_free(struct amdgpu_device *adev)
 	unsigned int order = get_order(adev->gart.table_size);
 	struct sg_table *sg = adev->gart.bo->tbo.sg;
 	struct page *p;
+	unsigned long x;
 	int ret;
 
 	ret = amdgpu_bo_reserve(adev->gart.bo, false);
@@ -234,6 +240,8 @@ void amdgpu_gart_table_ram_free(struct amdgpu_device *adev)
 	sg_free_table(sg);
 	kfree(sg);
 	p = virt_to_page(adev->gart.ptr);
+	for (x = 0; x < (1UL << order); x++)
+		p[x].mapping = NULL;
 	__free_pages(p, order);
 
 	adev->gart.ptr = NULL;