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Date:   Mon, 15 May 2023 10:07:27 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Niklas Schnelle <schnelle@linux.ibm.com>,
        Robin Murphy <robin.murphy@arm.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Matthew Rosato <mjrosato@linux.ibm.com>,
        Will Deacon <will@kernel.org>,
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        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        Hector Martin <marcan@marcan.st>,
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Subject: Re: [PATCH v9 5/6] iommu/dma: Allow a single FQ in addition to
 per-CPU FQs
Message-ID: <ZGIuj2pRjOPffqZZ@ziepe.ca>
References: <20230310-dma_iommu-v9-0-65bb8edd2beb@linux.ibm.com>
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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/cover.1683233867.git.robin.murphy@arm.com/

Jason