Commit e9416048 authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Joerg Roedel
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iommu: Generic support for RMRs during device release 



Generally an IOMMU driver should leave the translation as BLOCKED until the
translation entry is probed onto a struct device. When the struct device is
removed, the translation should be put back to BLOCKED.

Drivers that are able to work like this can set their release_domain to the
blocking domain, and the core code handles this work.

The exception is when the device has an IOMMU_RESV_DIRECT region, in which
case the OS should continuously allow translations for the given range. And
the core code generally prevents using a BLOCKED domain with this device.

Continue this logic for the device release and hoist some open coding from
drivers. If the device has dev->iommu->require_direct and the driver uses a
BLOCKED release_domain, override it to IDENTITY to preserve the semantics.

The only remaining required driver code for IOMMU_RESV_DIRECT should preset
an IDENTITY translation during early IOMMU startup for those devices.

Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent db340b02

drivers/iommu/iommu.c

+14 −2
Original line number Diff line number Diff line
@@ -542,8 +542,20 @@ static void iommu_deinit_device(struct device *dev) 
	 * 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 (!dev->iommu->attach_deferred && ops->release_domain) {

		struct iommu_domain *release_domain = ops->release_domain;



		/*

		 * If the device requires direct mappings then it should not

		 * be parked on a BLOCKED domain during release as that would

		 * break the direct mappings.

		 */

		if (dev->iommu->require_direct && ops->identity_domain &&

		    release_domain == ops->blocked_domain)

			release_domain = ops->identity_domain;



		release_domain->ops->attach_dev(release_domain, dev);

	}



	if (ops->release_device)

		ops->release_device(dev);