From: Joerg Roedel <[email protected]> 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. Cc: Jerry Snitselaar <[email protected]> Cc: Tom Murphy <[email protected]> Cc: Robin Murphy <[email protected]> Reported-by: Jerry Snitselaar <[email protected]> Suggested-by: Robin Murphy <[email protected]> Tested-by: Jerry Snitselaar <[email protected]> Fixes: 795bbbb9b6f8 ("iommu/dma-iommu: Handle deferred devices") Signed-off-by: Joerg Roedel <[email protected]> --- drivers/iommu/iommu.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 4050569188be..629d209b8e88 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -769,6 +769,15 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group, 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) @@ -821,7 +830,7 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev) 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) @@ -1893,9 +1902,6 @@ 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; @@ -1967,8 +1973,7 @@ 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)) -- 2.25.1
