Re: [PATCH v3 2/4] dma-iommu: Add iommu_dma_opt_mapping_size()

[Bart Van Assche]

On 6/6/22 02:30, John Garry via iommu wrote:
> +unsigned long iova_rcache_range(void)
> +{
> +	return PAGE_SIZE << (IOVA_RANGE_CACHE_MAX_SIZE - 1);
> +}

My understanding is that iova cache entries may be smaller than 
IOVA_RANGE_CACHE_MAX_SIZE and hence that even if code that uses the DMA 
mapping API respects this limit that a cache miss can still happen.

Thanks,

Bart.