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

Hillf Danton hdanton at sina.com
Fri Aug 16 20:39:14 PDT 2019


On Thu, 15 Aug 2019 12:09:41 +0100 Tom Murphy wrote:
> 
> Handle devices which defer their attach to the iommu in the dma-iommu api
> 
> Signed-off-by: Tom Murphy <murphyt7 at 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);

iommu_map_atomic() is applied to __iommu_dma_map() in 2/5.
Is it an atomic context currently given the mutex_lock() in
iommu_attach_device()?




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