Merge tag 'for-joerg' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd...

iommu: Define EINVAL as device/domain incompatibility

This series is to replace the previous EMEDIUMTYPE patch in a VFIO series:
https://lore.kernel.org/kvm/Yxnt9uQTmbqul5lf@8bytes.org/

The purpose is to regulate all existing ->attach_dev callback functions to
use EINVAL exclusively for an incompatibility error between a device and a
domain. This allows VFIO and IOMMUFD to detect such a soft error, and then
try a different domain with the same device.

Among all the patches, the first two are preparatory changes. And then one
patch to update kdocs and another three patches for the enforcement
effort.

Link: https://lore.kernel.org/r/cover.1666042872.git.nicolinc@nvidia.com

diff --cc drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
Simple merge

diff --cc drivers/iommu/intel/iommu.c
Simple merge

diff --cc drivers/iommu/iommu.c
Simple merge

diff --cc include/linux/iommu.h
index 7d2648058e439e75ec5c3dddd2dc424353672f3b,857898d102b365a1b5e852d048e9180d2a4ec368..68d7d304cdb761ebaa7c143c8e34736d722ef550
--- 1/include/linux/iommu.h
--- 2/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@@ -278,8 -266,19 +278,20 @@@ struct iommu_ops 
  /**
   * struct iommu_domain_ops - domain specific operations
   * @attach_dev: attach an iommu domain to a device
+  *  Return:
+  * * 0                - success
+  * * EINVAL   - can indicate that device and domain are incompatible due to
+  *              some previous configuration of the domain, in which case the
+  *              driver shouldn't log an error, since it is legitimate for a
+  *              caller to test reuse of existing domains. Otherwise, it may
+  *              still represent some other fundamental problem
+  * * ENOMEM   - out of memory
+  * * ENOSPC   - non-ENOMEM type of resource allocation failures
+  * * EBUSY    - device is attached to a domain and cannot be changed
+  * * ENODEV   - device specific errors, not able to be attached
+  * * <others> - treated as ENODEV by the caller. Use is discouraged
   * @detach_dev: detach an iommu domain from a device
 + * @set_dev_pasid: set an iommu domain to a pasid of device
   * @map: map a physically contiguous memory region to an iommu domain
   * @map_pages: map a physically contiguous set of pages of the same size to
   *             an iommu domain.