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    Subject[PATCH 06/11] iommu: Expose group variants of dma ownership interfaces
    Date
    The vfio needs to set DMA_OWNER_USER for the entire group when attaching
    it to a vfio container. So expose group variants of setting/releasing dma
    ownership for this purpose.

    This also exposes the helper iommu_group_dma_owner_unclaimed() for vfio
    report to userspace if the group is viable to user assignment, for
    compatibility with VFIO_GROUP_FLAGS_VIABLE.

    Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
    ---
    include/linux/iommu.h | 21 ++++++++++++++++
    drivers/iommu/iommu.c | 57 +++++++++++++++++++++++++++++++++++++++++++
    2 files changed, 78 insertions(+)

    diff --git a/include/linux/iommu.h b/include/linux/iommu.h
    index f77eb9e7788a..3d2dfd220d3c 100644
    --- a/include/linux/iommu.h
    +++ b/include/linux/iommu.h
    @@ -696,6 +696,10 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle);
    int iommu_device_set_dma_owner(struct device *dev, enum iommu_dma_owner owner,
    struct file *user_file);
    void iommu_device_release_dma_owner(struct device *dev, enum iommu_dma_owner owner);
    +int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner,
    + struct file *user_file);
    +void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner);
    +bool iommu_group_dma_owner_unclaimed(struct iommu_group *group);

    #else /* CONFIG_IOMMU_API */

    @@ -1112,6 +1116,23 @@ static inline void iommu_device_release_dma_owner(struct device *dev,
    enum iommu_dma_owner owner)
    {
    }
    +
    +static inline int iommu_group_set_dma_owner(struct iommu_group *group,
    + enum iommu_dma_owner owner,
    + struct file *user_file)
    +{
    + return -EINVAL;
    +}
    +
    +static inline void iommu_group_release_dma_owner(struct iommu_group *group,
    + enum iommu_dma_owner owner)
    +{
    +}
    +
    +static inline bool iommu_group_dma_owner_unclaimed(struct iommu_group *group)
    +{
    + return false;
    +}
    #endif /* CONFIG_IOMMU_API */

    /**
    diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
    index 916a4d448150..3dcd3fc4290a 100644
    --- a/drivers/iommu/iommu.c
    +++ b/drivers/iommu/iommu.c
    @@ -3431,6 +3431,63 @@ static void __iommu_group_release_dma_owner(struct iommu_group *group,
    }
    }

    +/**
    + * iommu_group_set_dma_owner() - Set DMA ownership of a group
    + * @group: The group.
    + * @owner: DMA_OWNER_KERNEL or DMA_OWNER_USER.
    + * @user_file: The device fd when set USER ownership.
    + *
    + * This is to support backward compatibility for legacy vfio which manages
    + * dma ownership in group level. New invocations on this interface should be
    + * prohibited. Instead, please turn to iommu_device_set_dma_owner().
    + */
    +int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner,
    + struct file *user_file)
    +{
    + int ret;
    +
    + mutex_lock(&group->mutex);
    + ret = __iommu_group_set_dma_owner(group, owner, user_file);
    + mutex_unlock(&group->mutex);
    +
    + return ret;
    +}
    +EXPORT_SYMBOL_GPL(iommu_group_set_dma_owner);
    +
    +/**
    + * iommu_group_release_dma_owner() - Release DMA ownership of a group
    + * @group: The group.
    + * @owner: DMA_OWNER_KERNEL or DMA_OWNER_USER.
    + *
    + * Release the DMA ownership claimed by iommu_group_set_dma_owner().
    + */
    +void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner)
    +{
    + mutex_lock(&group->mutex);
    + __iommu_group_release_dma_owner(group, owner);
    + mutex_unlock(&group->mutex);
    +}
    +EXPORT_SYMBOL_GPL(iommu_group_release_dma_owner);
    +
    +/**
    + * iommu_group_dma_owner_unclaimed() - Is group dma ownership claimed
    + * @group: The group.
    + *
    + * This provides status check on a given group. It is racey and only for
    + * non-binding status reporting.
    + */
    +bool iommu_group_dma_owner_unclaimed(struct iommu_group *group)
    +{
    + enum iommu_dma_owner owner;
    +
    + mutex_lock(&group->mutex);
    + owner = group->dma_owner;
    + mutex_unlock(&group->mutex);
    +
    + return owner == DMA_OWNER_NONE;
    +}
    +EXPORT_SYMBOL_GPL(iommu_group_dma_owner_unclaimed);
    +
    /**
    * iommu_device_set_dma_owner() - Set DMA ownership of a device
    * @dev: The device.
    --
    2.25.1
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