[PATCH v10 10/12] swiotlb: Add restricted DMA alloc/free support

[Christoph Hellwig]

On Tue, Jun 15, 2021 at 09:27:09PM +0800, Claire Chang wrote:
> Add the functions, swiotlb_{alloc,free} to support the memory allocation
> from restricted DMA pool.
> 
> The restricted DMA pool is preferred if available.
> 
> Note that since coherent allocation needs remapping, one must set up
> another device coherent pool by shared-dma-pool and use
> dma_alloc_from_dev_coherent instead for atomic coherent allocation.

Note: when applied this should go before the next patch to make sure
bisection works fine.

>  #ifdef CONFIG_DMA_RESTRICTED_POOL
> +struct page *swiotlb_alloc(struct device *dev, size_t size)
> +{
> +	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
> +	phys_addr_t tlb_addr;
> +	int index;
> +
> +	/*
> +	 * Skip io_tlb_default_mem since swiotlb_alloc doesn't support atomic
> +	 * coherent allocation. Otherwise might break existing devices.
> +	 * One must set up another device coherent pool by shared-dma-pool and
> +	 * use dma_alloc_from_dev_coherent instead for atomic coherent
> +	 * allocation to avoid mempry remapping.

s/mempry/memory/g

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch at lst.de>