This is a note to let you know that I've just added the patch titled
iommu: Add static iommu_ops->release_domain
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iommu-add-static-iommu_ops-release_domain.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 23c614c7241cb347538937012be2dd3c1deceb82
Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Date: Tue Mar 5 20:21:17 2024 +0800
iommu: Add static iommu_ops->release_domain
[ Upstream commit 0061ffe289e19caabeea8103e69cb0f1896e34d8 ]
The current device_release callback for individual iommu drivers does the
following:
1) Silent IOMMU DMA translation: It detaches any existing domain from the
device and puts it into a blocking state (some drivers might use the
identity state).
2) Resource release: It releases resources allocated during the
device_probe callback and restores the device to its pre-probe state.
Step 1 is challenging for individual iommu drivers because each must check
if a domain is already attached to the device. Additionally, if a deferred
attach never occurred, the device_release should avoid modifying hardware
configuration regardless of the reason for its call.
To simplify this process, introduce a static release_domain within the
iommu_ops structure. It can be either a blocking or identity domain
depending on the iommu hardware. The iommu core will decide whether to
attach this domain before the device_release callback, eliminating the
need for repetitive code in various drivers.
Consequently, the device_release callback can focus solely on the opposite
operations of device_probe, including releasing all resources allocated
during that callback.
Co-developed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Link: https://lore.kernel.org/r/20240305013305.204605-2-baolu.lu@xxxxxxxxxxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Stable-dep-of: 81e921fd3216 ("iommu/vt-d: Fix NULL domain on device release")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d14413916f93a..cd1210026ac53 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -463,13 +463,24 @@ static void iommu_deinit_device(struct device *dev)
/*
* release_device() must stop using any attached domain on the device.
- * If there are still other devices in the group they are not effected
+ * If there are still other devices in the group, they are not affected
* by this callback.
*
- * The IOMMU driver must set the device to either an identity or
- * blocking translation and stop using any domain pointer, as it is
- * going to be freed.
+ * If the iommu driver provides release_domain, the core code ensures
+ * that domain is attached prior to calling release_device. Drivers can
+ * use this to enforce a translation on the idle iommu. Typically, the
+ * global static blocked_domain is a good choice.
+ *
+ * Otherwise, the iommu driver must set the device to either an identity
+ * or a blocking translation in release_device() and stop using any
+ * domain pointer, as it is going to be freed.
+ *
+ * Regardless, if a delayed attach never occurred, then the release
+ * should still avoid touching any hardware configuration either.
*/
+ if (!dev->iommu->attach_deferred && ops->release_domain)
+ ops->release_domain->ops->attach_dev(ops->release_domain, dev);
+
if (ops->release_device)
ops->release_device(dev);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5e27cb3a3be99..c948289f64d08 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -487,6 +487,7 @@ struct iommu_ops {
struct module *owner;
struct iommu_domain *identity_domain;
struct iommu_domain *blocked_domain;
+ struct iommu_domain *release_domain;
struct iommu_domain *default_domain;
};
