From: Joerg Roedel jroedel@suse.de
[ Upstream commit bd421264ed307dd296eab036851221b225071a32 ]
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: 795bbbb9b6f8 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 8d2477941fd9..22b28076d48e 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -692,6 +692,15 @@ static int iommu_group_create_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) @@ -746,7 +755,7 @@ 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) @@ -1652,9 +1661,6 @@ 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; @@ -1726,8 +1732,7 @@ 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))