[PATCH v5 23/25] iommu: Add ops->domain_alloc_paging()

[Baolu Lu]

On 2023/7/25 1:22, Jason Gunthorpe wrote:
> This callback requests the driver to create only a __IOMMU_DOMAIN_PAGING
> domain, so it saves a few lines in a lot of drivers needlessly checking
> the type.
> 
> More critically, this allows us to sweep out all the
> IOMMU_DOMAIN_UNMANAGED and IOMMU_DOMAIN_DMA checks from a lot of the
> drivers, simplifying what is going on in the code and ultimately removing
> the now-unused special cases in drivers where they did not support
> IOMMU_DOMAIN_DMA.
> 
> domain_alloc_paging() should return a struct iommu_domain that is
> functionally compatible with ARM_DMA_USE_IOMMU, dma-iommu.c and iommufd.
> 
> Be forwards looking and pass in a 'struct device *' argument. We can
> provide this when allocating the default_domain. No drivers will look at
> this.
> 
> Tested-by: Steven Price<steven.price at arm.com>
> Tested-by: Marek Szyprowski<m.szyprowski at samsung.com>
> Tested-by: Nicolin Chen<nicolinc at nvidia.com>
> Signed-off-by: Jason Gunthorpe<jgg at nvidia.com>
> ---
>   drivers/iommu/iommu.c | 13 ++++++++++---
>   include/linux/iommu.h |  3 +++
>   2 files changed, 13 insertions(+), 3 deletions(-)

Reviewed-by: Lu Baolu <baolu.lu at linux.intel.com>