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.patel@xxxxxxxxxxxx> --- 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
