Not allowing No-IOMMU mode for devices already having iommu_ops on their bus is little conservative. We now have IOMMU (such as ARM SMMU) which can bypass transcations for which IOMMU domain is not configured hence No-IOMMU mode should not be allowed when iommu_ops are available and IOMMU_CAP_BYPASS is not available. Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxxxx> --- drivers/vfio/vfio.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 330d505..61f3807 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -124,11 +124,18 @@ 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 + * that: + * 1. Doesn't already have IOMMU group + * 2. Doesn't have an iommu_ops on their bus + * 3. Doesn't have transaction bypass capability if iommu_ops + * is available on their bus + * + * 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 || + (iommu_present(dev->bus) && + !iommu_capable(dev->bus, IOMMU_CAP_BYPASS))) return group; group = iommu_group_alloc(); -- 2.7.4
