On Thu, Sep 22, 2022 at 01:54:08AM -0700, Nicolin Chen wrote: > Cases like VFIO wish to attach a device to an existing domain that was > not allocated specifically from the device. This raises a condition > where the IOMMU driver can fail the domain attach because the domain and > device are incompatible with each other. > > This is a soft failure that can be resolved by using a different domain. > > Provide a dedicated errno EINVAL from the IOMMU driver during attach that > the reason why the attach failed is because of domain incompatibility. > > VFIO can use this to know that the attach is a soft failure and it should > continue searching. Otherwise, the attach will be a hard failure and VFIO > will return the code to userspace. > > Update kdocs to add rules of return value to the attach_dev op and APIs. > > Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx> > Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx> > Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx> > --- > drivers/iommu/iommu.c | 24 ++++++++++++++++++++++++ > include/linux/iommu.h | 12 ++++++++++++ > 2 files changed, 36 insertions(+) Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Jason
