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

Robin Murphy
2019-08-19T18:26:18Z

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);
>
>