From: Lu Baolu baolu.lu@linux.intel.com
[ 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@nvidia.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Lu Baolu baolu.lu@linux.intel.com Reviewed-by: Kevin Tian kevin.tian@intel.com Link: https://lore.kernel.org/r/20240305013305.204605-2-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel jroedel@suse.de Stable-dep-of: 81e921fd3216 ("iommu/vt-d: Fix NULL domain on device release") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/iommu.c | 19 +++++++++++++++---- include/linux/iommu.h | 1 + 2 files changed, 16 insertions(+), 4 deletions(-)
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; };