Re: [RFC PATCH v2 04/19] iommu: Introduce struct iommu_iotlb_gather for batching TLB flushes

From: Joerg Roedel <joro@8bytes.org>
To: Will Deacon <will@kernel.org>
Cc: Vijay Kilary <vkilari@codeaurora.org>,
	Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
	Jon Masters <jcm@redhat.com>, Jan Glauber <jglauber@marvell.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	iommu@lists.linux-foundation.org,
	Jayachandran Chandrasekharan Nair <jnair@marvell.com>,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [RFC PATCH v2 04/19] iommu: Introduce struct iommu_iotlb_gather for batching TLB flushes
Date: Wed, 24 Jul 2019 09:19:59 +0200	[thread overview]
Message-ID: <20190724071959.GE1524@8bytes.org> (raw)
In-Reply-To: <20190711171927.28803-5-will@kernel.org>

Hi Will,

On Thu, Jul 11, 2019 at 06:19:12PM +0100, Will Deacon wrote:
>  static void __iommu_dma_unmap(struct iommu_domain *domain, dma_addr_t dma_addr,
>  		size_t size)
>  {
> +	struct iommu_iotlb_gather iotlb_gather;
>  	struct iommu_dma_cookie *cookie = domain->iova_cookie;
>  	struct iova_domain *iovad = &cookie->iovad;
>  	size_t iova_off = iova_offset(iovad, dma_addr);
> +	size_t unmapped;
>  
>  	dma_addr -= iova_off;
>  	size = iova_align(iovad, size + iova_off);
> +	iommu_iotlb_gather_init(&iotlb_gather);
> +
> +	unmapped = iommu_unmap_fast(domain, dma_addr, size, &iotlb_gather);
> +	WARN_ON(unmapped != size);
>  
> -	WARN_ON(iommu_unmap_fast(domain, dma_addr, size) != size);
>  	if (!cookie->fq_domain)
> -		iommu_tlb_sync(domain);
> +		iommu_tlb_sync(domain, &iotlb_gather);
>  	iommu_dma_free_iova(cookie, dma_addr, size);

I looked through your patches and was wondering if we can't make the
'struct iotlb_gather' a member of 'struct iommu_domain' and update it
transparently for the user? That would make things easier for users of
the iommu-api.

Regards,

	Joerg
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