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 <murph...@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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