Re: [PATCH v2 17/29] drm/xe: Add SVM device memory mirroring

[Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>]

On 10/16/24 6:25 AM, Matthew Brost wrote:
> +/**
> + * xe_devm_add: Remap and provide memmap backing for device memory
> + * @tile: tile that the memory region belongs to
> + * @mr: memory region to remap
> + *
> + * This remap device memory to host physical address space and create
> + * struct page to back device memory
> + *
> + * Return: 0 on success standard error code otherwise
> + */
> +int xe_devm_add(struct xe_tile *tile, struct xe_mem_region *mr)
> +{
> +	struct xe_device *xe = tile_to_xe(tile);
> +	struct device *dev = &to_pci_dev(xe->drm.dev)->dev;
> +	struct resource *res;
> +	void *addr;
> +	int ret;
> +
> +	res = devm_request_free_mem_region(dev, &iomem_resource,
> +					   mr->usable_size);
To use the devm_request_free_mem_region() function, 
CONFIG_GET_FREE_REGION=y in config.
xe's kconfig need to have CONFIG_GET_FREE_REGION dependency.
> +	if (IS_ERR(res)) {
> +		ret = PTR_ERR(res);
> +		return ret;
> +	}
> +
> +	mr->pagemap.type = MEMORY_DEVICE_PRIVATE;
> +	mr->pagemap.range.start = res->start;
> +	mr->pagemap.range.end = res->end;
> +	mr->pagemap.nr_range = 1;
> +	mr->pagemap.ops = drm_gpusvm_pagemap_ops_get();
> +	mr->pagemap.owner = xe_svm_devm_owner(xe);
> +	addr = devm_memremap_pages(dev, &mr->pagemap);
> +	if (IS_ERR(addr)) {
> +		devm_release_mem_region(dev, res->start, resource_size(res));
> +		ret = PTR_ERR(addr);
> +		drm_err(&xe->drm, "Failed to remap tile %d memory, errno %d\n",
> +				tile->id, ret);
> +		return ret;
> +	}
> +	mr->hpa_base = res->start;
> +
> +	drm_info(&xe->drm, "Added tile %d memory [%llx-%llx] to devm, remapped to %pr\n",
> +		 tile->id, mr->io_start, mr->io_start + mr->usable_size, res);
> +	return 0;
> +}