From: Jason Gunthorpe <[email protected]> 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: Jason Gunthorpe <[email protected]> Signed-off-by: Nicolin Chen <[email protected]> --- drivers/iommu/iommu.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 59244c744eabd..adef1a37f9311 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -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); -- 2.43.0
