Allow use of the No-IOMMU mode even if a real IOMMU is present.
This is useful in case the device is not part of an actual IOMMU group.
Not-Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
Question:
- Some devices (e.g. rcar-gpio) don't use DMA, so why do they need an
IOMMU group?
- Even devices using DMA may do so using a separate DMAC module,
pointed to by "dmas" DT properties (e.g. sh-sci), hence they may be
not part of an IOMMU group.
- How to know which devices do DMA?
---
drivers/vfio/vfio.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 2bc3705a99bd2f1a..7736c3fbe468a3da 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -129,9 +129,13 @@ struct iommu_group *vfio_iommu_group_get(struct device *dev)
* 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)
return group;
+ if (iommu_present(dev->bus))
+ dev_warn(dev, "iommu present (%ps), ignoring\n",
+ dev->bus->iommu_ops);
+
group = iommu_group_alloc();
if (IS_ERR(group))
return NULL;
--
2.7.4
