iommu: Fix deferred domain attachment (bd421264) · Commits · 戴 / test

The IOMMU core code has support for deferring the attachment of a domain to a device. This is needed in kdump kernels where the new domain must not be attached to a device before the device driver takes it over. When the AMD IOMMU driver got converted to use the dma-iommu implementation, the deferred attaching got lost. The code in dma-iommu.c has support for deferred attaching, but it calls into iommu_attach_device() to actually do it. But iommu_attach_device() will check if the device should be deferred in it code-path and do nothing, breaking deferred attachment. Move the is_deferred_attach() check out of the attach_device path and into iommu_group_add_device() to make deferred attaching work from the dma-iommu code. Fixes: ("iommu/dma-iommu: Handle deferred devices") Reported-by:

Jerry Snitselaar <jsnitsel@redhat.com> Suggested-by:

Robin Murphy <robin.murphy@arm.com> Signed-off-by:

Joerg Roedel <jroedel@suse.de> Tested-by:

Jerry Snitselaar <jsnitsel@redhat.com> Cc: Jerry Snitselaar <jsnitsel@redhat.com> Cc: Tom Murphy <murphyt7@tcd.ie> Cc: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/20200519130340.14564-1-joro@8bytes.org

drivers/iommu/iommu.c

+11 −6

Original line number	Diff line number	Diff line
		@@ -693,6 +693,15 @@ out:
		return ret;
		}

		static bool iommu_is_attach_deferred(struct iommu_domain *domain,
		struct device *dev)
		{
		if (domain->ops->is_attach_deferred)
		return domain->ops->is_attach_deferred(domain, dev);

		return false;
		}

		/**
		* iommu_group_add_device - add a device to an iommu group
		* @group: the group into which to add the device (reference should be held)
		@@ -747,7 +756,7 @@ rename:

		mutex_lock(&group->mutex);
		list_add_tail(&device->list, &group->devices);
		if (group->domain)
		if (group->domain && !iommu_is_attach_deferred(group->domain, dev))
		ret = __iommu_attach_device(group->domain, dev);
		mutex_unlock(&group->mutex);
		if (ret)
		@@ -1653,9 +1662,6 @@ static int __iommu_attach_device(struct iommu_domain *domain,
		struct device *dev)
		{
		int ret;
		if ((domain->ops->is_attach_deferred != NULL) &&
		domain->ops->is_attach_deferred(domain, dev))
		return 0;

		if (unlikely(domain->ops->attach_dev == NULL))
		return -ENODEV;
		@@ -1727,8 +1733,7 @@ EXPORT_SYMBOL_GPL(iommu_sva_unbind_gpasid);
		static void __iommu_detach_device(struct iommu_domain *domain,
		struct device *dev)
		{
		if ((domain->ops->is_attach_deferred != NULL) &&
		domain->ops->is_attach_deferred(domain, dev))
		if (iommu_is_attach_deferred(domain, dev))
		return;

		if (unlikely(domain->ops->detach_dev == NULL))

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