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

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

1 files changed, 24 insertions, 0 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index c50f68b2b656..6ca377f4fbf9 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1976,6 +1976,18 @@ static int __iommu_attach_device(struct iommu_domain *domain,
 	return ret;
 }
 
+/**
+ * iommu_attach_device - Attach an IOMMU domain to a device
+ * @domain: IOMMU domain to attach
+ * @dev: Device that will be attached
+ *
+ * Returns 0 on success and error code on failure
+ *
+ * Note that EINVAL can be treated as a soft failure, indicating
+ * that certain configuration of the domain is incompatible with
+ * the device. In this case attaching a different domain to the
+ * device may succeed.
+ */
 int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
 {
 	struct iommu_group *group;
@@ -2102,6 +2114,18 @@ static int __iommu_attach_group(struct iommu_domain *domain,
 	return ret;
 }
 
+/**
+ * iommu_attach_group - Attach an IOMMU domain to an IOMMU group
+ * @domain: IOMMU domain to attach
+ * @group: IOMMU group that will be attached
+ *
+ * Returns 0 on success and error code on failure
+ *
+ * Note that EINVAL can be treated as a soft failure, indicating
+ * that certain configuration of the domain is incompatible with
+ * the group. In this case attaching a different domain to the
+ * group may succeed.
+ */
 int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
 {
 	int ret;