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SubjectRe: [PATCH v7 08/10] iommu/dma-reserved_iommu: iommu_msi_mapping_desc_to_domain
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On 19/04/16 17:56, Eric Auger wrote:
> This function checks whether
> - the device emitting the MSI belongs to a non default iommu domain
> - the iommu domain requires the MSI address to be mapped.
>
> If those conditions are met, the function returns the iommu domain
> to be used for mapping the MSI doorbell; else it returns NULL.
>
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
> ---
> drivers/iommu/dma-reserved-iommu.c | 19 +++++++++++++++++++
> include/linux/dma-reserved-iommu.h | 18 ++++++++++++++++++
> 2 files changed, 37 insertions(+)
>
> diff --git a/drivers/iommu/dma-reserved-iommu.c b/drivers/iommu/dma-reserved-iommu.c
> index 2522235..907a17f 100644
> --- a/drivers/iommu/dma-reserved-iommu.c
> +++ b/drivers/iommu/dma-reserved-iommu.c
> @@ -17,6 +17,7 @@
>
> #include <linux/iommu.h>
> #include <linux/iova.h>
> +#include <linux/msi.h>
>
> struct reserved_iova_domain {
> struct iova_domain *iovad;
> @@ -332,3 +333,21 @@ unlock:
> }
> EXPORT_SYMBOL_GPL(iommu_put_reserved_iova);
>
> +struct iommu_domain *iommu_msi_mapping_desc_to_domain(struct msi_desc *desc)
> +{
> + struct device *dev;
> + struct iommu_domain *d;
> +
> + dev = msi_desc_to_dev(desc);
> +
> + d = iommu_get_domain_for_dev(dev);
> +
> + if (!d || (d->type == IOMMU_DOMAIN_DMA))
> + return NULL;
> +
> + if (iommu_domain_get_attr(d, DOMAIN_ATTR_MSI_MAPPING, NULL))
> + return NULL;

Yeah, I don't see why we couldn't just use

if (domain->ops->capable(IOMMU_CAP_INTR_REMAP))
return NULL

there instead.

> +
> + return d;
> +}
> +EXPORT_SYMBOL_GPL(iommu_msi_mapping_desc_to_domain);
> diff --git a/include/linux/dma-reserved-iommu.h b/include/linux/dma-reserved-iommu.h
> index 8722131..8373929 100644
> --- a/include/linux/dma-reserved-iommu.h
> +++ b/include/linux/dma-reserved-iommu.h
> @@ -19,6 +19,7 @@
> #include <linux/kernel.h>
>
> struct iommu_domain;
> +struct msi_desc;
>
> #ifdef CONFIG_IOMMU_DMA_RESERVED
>
> @@ -70,6 +71,17 @@ int iommu_get_reserved_iova(struct iommu_domain *domain,
> * if the binding ref count is null, destroy the reserved mapping
> */
> void iommu_put_reserved_iova(struct iommu_domain *domain, phys_addr_t addr);
> +
> +/**
> + * iommu_msi_mapping_desc_to_domain: in case the MSI originates from a device
> + * upstream to an IOMMU and this IOMMU translates the MSI transaction,
> + * this function returns the iommu domain the MSI doorbell address must be
> + * mapped in. Else it returns NULL.
> + *
> + * @desc: msi desc handle
> + */
> +struct iommu_domain *iommu_msi_mapping_desc_to_domain(struct msi_desc *desc);
> +
> #else
>
> static inline int
> @@ -93,5 +105,11 @@ static inline int iommu_get_reserved_iova(struct iommu_domain *domain,
> static inline void iommu_put_reserved_iova(struct iommu_domain *domain,
> phys_addr_t addr) {}
>
> +static inline struct iommu_domain *
> +iommu_msi_mapping_desc_to_domain(struct msi_desc *desc)
> +{
> + return NULL;
> +}
> +
> #endif /* CONFIG_IOMMU_DMA_RESERVED */
> #endif /* __DMA_RESERVED_IOMMU_H */
>

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