Re: [PATCH V5 3/5] iommu/dma-iommu: Handle deferred devices

From: Robin Murphy <robin.murphy@arm•com>
To: Tom Murphy <murphyt7@tcd•ie>, iommu@lists•linux-foundation.org
Cc: Heiko Stuebner <heiko@sntech•de>,
	virtualization@lists•linux-foundation.org,
	Matthias Brugger <matthias.bgg@gmail•com>,
	Thierry Reding <thierry.reding@gmail•com>,
	Will Deacon <will@kernel•org>,
	Marek Szyprowski <m.szyprowski@samsung•com>,
	Jean-Philippe Brucker <jean-philippe@linaro•org>,
	linux-samsung-soc@vger•kernel.org, Joerg Roedel <joro@8bytes•org>,
	Krzysztof Kozlowski <krzk@kernel•org>,
	Jonathan Hunter <jonathanh@nvidia•com>,
	linux-rockchip@lists•infradead.org,
	Andy Gross <agross@kernel•org>,
	Gerald Schaefer <gerald.schaefer@de•ibm.com>,
	linux-s390@vger•kernel.org, linux-arm-msm@vger•kernel.org,
	linux-mediatek@lists•infradead.org, linux-tegra@vger•kernel.org,
	linux-arm-kernel@lists•infradead.org,
	linux-kernel@vger•kernel.org, Rob Clark <robdclark@gmail•com>,
	Kukjin Kim <kgene@kernel•org>,
	David Woodhouse <dwmw2@infradead•org>
Subject: Re: [PATCH V5 3/5] iommu/dma-iommu: Handle deferred devices
Date: Mon, 19 Aug 2019 19:26:08 +0100	[thread overview]
Message-ID: <5a12defd-b68d-bd2d-da5a-16628a1f5b91@arm.com> (raw)
In-Reply-To: <20190815110944.3579-4-murphyt7@tcd.ie>

On 15/08/2019 12:09, Tom Murphy wrote:
> Handle devices which defer their attach to the iommu in the dma-iommu api

Other than nitpicking the name (I'd lean towards something like 
iommu_dma_deferred_attach),

Reviewed-by: Robin Murphy <robin.murphy@arm•com>

> Signed-off-by: Tom Murphy <murphyt7@tcd•ie>
> ---
>   drivers/iommu/dma-iommu.c | 27 ++++++++++++++++++++++++++-
>   1 file changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 2712fbc68b28..906b7fa14d3c 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -22,6 +22,7 @@
>   #include <linux/pci.h>
>   #include <linux/scatterlist.h>
>   #include <linux/vmalloc.h>
> +#include <linux/crash_dump.h>
>   
>   struct iommu_dma_msi_page {
>   	struct list_head	list;
> @@ -351,6 +352,21 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
>   	return iova_reserve_iommu_regions(dev, domain);
>   }
>   
> +static int handle_deferred_device(struct device *dev,
> +	struct iommu_domain *domain)
> +{
> +	const struct iommu_ops *ops = domain->ops;
> +
> +	if (!is_kdump_kernel())
> +		return 0;
> +
> +	if (unlikely(ops->is_attach_deferred &&
> +		ops->is_attach_deferred(domain, dev)))
> +		return iommu_attach_device(domain, dev);
> +
> +	return 0;
> +}
> +
>   /**
>    * dma_info_to_prot - Translate DMA API directions and attributes to IOMMU API
>    *                    page flags.
> @@ -463,6 +479,9 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
>   	size_t iova_off = iova_offset(iovad, phys);
>   	dma_addr_t iova;
>   
> +	if (unlikely(handle_deferred_device(dev, domain)))
> +		return DMA_MAPPING_ERROR;
> +
>   	size = iova_align(iovad, size + iova_off);
>   
>   	iova = iommu_dma_alloc_iova(domain, size, dma_get_mask(dev), dev);
> @@ -581,6 +600,9 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
>   
>   	*dma_handle = DMA_MAPPING_ERROR;
>   
> +	if (unlikely(handle_deferred_device(dev, domain)))
> +		return NULL;
> +
>   	min_size = alloc_sizes & -alloc_sizes;
>   	if (min_size < PAGE_SIZE) {
>   		min_size = PAGE_SIZE;
> @@ -713,7 +735,7 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
>   	int prot = dma_info_to_prot(dir, coherent, attrs);
>   	dma_addr_t dma_handle;
>   
> -	dma_handle =__iommu_dma_map(dev, phys, size, prot);
> +	dma_handle = __iommu_dma_map(dev, phys, size, prot);
>   	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
>   	    dma_handle != DMA_MAPPING_ERROR)
>   		arch_sync_dma_for_device(dev, phys, size, dir);
> @@ -823,6 +845,9 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
>   	unsigned long mask = dma_get_seg_boundary(dev);
>   	int i;
>   
> +	if (unlikely(handle_deferred_device(dev, domain)))
> +		return 0;
> +
>   	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
>   		iommu_dma_sync_sg_for_device(dev, sg, nents, dir);
>   
> 

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