[PATCH v7 08/24] iommu: Reorganize iommu_get_default_domain_type() to respect def_domain_type()

[Jerry Snitselaar]

On Wed, Aug 23, 2023 at 01:47:22PM -0300, Jason Gunthorpe wrote:
> Except for dart (which forces IOMMU_DOMAIN_DMA) every driver returns 0 or
> IDENTITY from ops->def_domain_type().
> 
> The drivers that return IDENTITY have some kind of good reason, typically
> that quirky hardware really can't support anything other than IDENTITY.
> 
> Arrange things so that if the driver says it needs IDENTITY then
> iommu_get_default_domain_type() either fails or returns IDENTITY.  It will
> not ignore the driver's override to IDENTITY.
> 
> Split the function into two steps, reducing the group device list to the
> driver's def_domain_type() and the untrusted flag.
> 
> Then compute the result based on those two reduced variables. Fully reject
> combining untrusted with IDENTITY.
> 
> Remove the debugging print on the iommu_group_store_type() failure path,
> userspace should not be able to trigger kernel prints.
> 
> This makes the next patch cleaner that wants to force IDENTITY always for
> ARM_IOMMU because there is no support for DMA.
> 
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> ---
>  drivers/iommu/iommu.c | 117 ++++++++++++++++++++++++++++--------------
>  1 file changed, 79 insertions(+), 38 deletions(-)
> 

Reviewed-by: Jerry Snitselaar <jsnitsel at redhat.com>