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    Subject[PATCH v7 08/10] iommu/dma-reserved_iommu: iommu_msi_mapping_desc_to_domain
    Date
    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;
    +
    + 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 */
    --
    1.9.1
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