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.pa...@broadcom.com>
---
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
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