Messages in this thread | | | Date | Fri, 1 Jul 2022 14:53:13 +0800 | Subject | Re: [PATCH v4 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group | From | Baolu Lu <> |
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On 2022/7/1 04:36, 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 from the IOMMU driver during attach that the > reason attached failed is because of domain incompatability. EMEDIUMTYPE > is chosen because it is never used within the iommu subsystem today and > evokes a sense that the 'medium' aka the domain is incompatible. > > VFIO can use this to know 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 all drivers to return EMEDIUMTYPE in their failure paths that are > related to domain incompatability. Also remove adjacent error prints for > these soft failures, to prevent a kernel log spam, since -EMEDIUMTYPE is > clear enough to indicate an incompatability error. > > Add kdocs describing this behavior. > > Suggested-by: Jason Gunthorpe<jgg@nvidia.com> > Reviewed-by: Kevin Tian<kevin.tian@intel.com> > Signed-off-by: Nicolin Chen<nicolinc@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Best regards, baolu
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