iommu: Don't print warning when IOMMU driver only supports unmanaged domains

Print the warning about the fall-back to IOMMU_DOMAIN_DMA in
iommu_group_get_for_dev() only when such a domain was
actually allocated.

Otherwise the user will get misleading warnings in the
kernel log when the iommu driver used doesn't support
IOMMU_DOMAIN_DMA and IOMMU_DOMAIN_IDENTITY.

Fixes: fccb4e3b8ab09 ('iommu: Allow default domain type to be set on the kernel command line')
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 33a982e..109de67 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1105,10 +1105,12 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev)
 
                dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type);
                if (!dom && iommu_def_domain_type != IOMMU_DOMAIN_DMA) {
-                       dev_warn(dev,
-                                "failed to allocate default IOMMU domain of type %u; falling back to IOMMU_DOMAIN_DMA",
-                                iommu_def_domain_type);
                        dom = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_DMA);
+                       if (dom) {
+                               dev_warn(dev,
+                                        "failed to allocate default IOMMU domain of type %u; falling back to IOMMU_DOMAIN_DMA",
+                                        iommu_def_domain_type);
+                       }
                }
 
                group->default_domain = dom;