Not allowing No-IOMMU mode for devices already having
iommu_ops on their bus is very conservative.
We now have IOMMU (such as ARM SMMU) which can bypass
transcations when IOMMU is not configured for a given
device. In addition, it is not necessary to have all
devices on bus to be upstream to an IOMMU on that bus.
Due above reasons, having iommu_present() check for
VFIO No-IOMMU mode is not appropriate.
Signed-off-by: Anup Patel <anup.pa...@broadcom.com>
---
drivers/vfio/vfio.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 330d505..9d90de7 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -124,11 +124,10 @@ struct iommu_group *vfio_iommu_group_get(struct device
*dev)
#ifdef CONFIG_VFIO_NOIOMMU
/*
* With noiommu enabled, an IOMMU group will be created for a device
- * that doesn't already have one and doesn't have an iommu_ops on their
- * bus. We set iommudata simply to be able to identify these groups
- * as special use and for reclamation later.
+ * that doesn't already have one. We set iommudata simply to be able
+ * to identify these groups as special use and for reclamation later.
*/
- if (group || !noiommu || iommu_present(dev->bus))
+ if (group || !noiommu)
return group;
group = iommu_group_alloc();
--
2.7.4
