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iommu: Fix deferred domain attachment 

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: 795bbbb9b6 ("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
This commit is contained in:
Joerg Roedel 2020-05-19 15:03:40 +02:00
parent ea90228c7b
commit bd421264ed
1 changed files with 11 additions and 6 deletions
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17
drivers/iommu/iommu.c
View File

@ -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))