Subject: Re: [PATCH v9 5/6] iommu/dma: Allow a single FQ in addition to per-CPU FQs

From: Jason Gunthorpe <[email-masked]>
Date: Mon, 15 May 2023 10:07:27 -0300

On Mon, May 15, 2023 at 11:15:55AM +0200, Niklas Schnelle wrote:

> +/**
> + * struct dma_iommu_options - Options for dma-iommu
> + *
> + * @flags: Flag bits for enabling/disabling dma-iommu settings
> + *
> + * This structure is intended to provide IOMMU drivers a way to influence the
> + * behavior of the dma-iommu DMA API implementation. This allows optimizing for
> + * example for a virtualized environment with slow IOTLB flushes.
> + */
> +struct dma_iommu_options {
> +#define IOMMU_DMA_OPTS_PER_CPU_QUEUE	(0L << 0)
> +#define IOMMU_DMA_OPTS_SINGLE_QUEUE	(1L << 0)
> +	u64	flags;
> +};

You need to hash it out with robin if we do something like this or use
more untyped caps as he put in this series:

https://lore.kernel.org/linux-iommu/[email-masked]/

Jason