Re: [PATCH v5 3/5] vfio/iommu_type1: Remove the domain->ops comparison

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Jul 01, 2022 at 02:44:53PM -0700, Nicolin Chen wrote:
> The domain->ops validation was added, as a precaution, for mixed-driver
> systems.
> 
> Per Robin's remarks,
> * While bus_set_iommu() still exists, the core code prevents multiple
>   drivers from registering, so we can't really run into a situation of
>   having a mixed-driver system:
>   https://lore.kernel.org/kvm/6e1280c5-4b22-ebb3-3912-6c72bc169982@arm.com/
> 
> * And there's plenty more significant problems than this to fix; in future
>   when many can be permitted, we will rely on the IOMMU core code to check
>   the domain->ops:
>   https://lore.kernel.org/kvm/6575de6d-94ba-c427-5b1e-967750ddff23@arm.com/
> 
> So remove the check in VFIO for simplicity.
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 32 +++++++++++---------------------
>  1 file changed, 11 insertions(+), 21 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason