[PATCH V2 06/11] vfio: Introduce and set noiommu flag on vfio_device

Jacob Pan
2026-03-12T15:56:51Z

When a VFIO device is added to a noiommu group, set the noiommu flag on
the vfio_device structure to indicate that the device operates in
noiommu mode.

Also update function signatures to pass vfio_device instead of device,
which has the direct access to the noiommu flag.

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
drivers/vfio/group.c | 21 +++++++++++----------
include/linux/vfio.h | 1 +
2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index 98f2a4f2ebff..6f98c57de9e0 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -588,7 +588,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
return ret;
}

-static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
+static struct vfio_group *vfio_noiommu_group_alloc(struct vfio_device *vdev,
enum vfio_group_type type)
{
struct iommu_group *iommu_group;
@@ -610,7 +610,7 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
ret = iommu_group_set_name(iommu_group, "vfio-noiommu");
if (ret)
goto out_put_group;
- ret = iommu_group_add_device(iommu_group, dev);
+ ret = iommu_group_add_device(iommu_group, vdev->dev);
if (ret)
goto out_put_group;

@@ -625,7 +625,7 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
return group;

out_remove_device:
- iommu_group_remove_device(dev);
+ iommu_group_remove_device(vdev->dev);
out_put_group:
iommu_group_put(iommu_group);
return ERR_PTR(ret);
@@ -646,23 +646,24 @@ static bool vfio_group_has_device(struct vfio_group *group, struct device *dev)
return false;
}

-static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
+static struct vfio_group *vfio_group_find_or_alloc(struct vfio_device *vdev)
{
struct iommu_group *iommu_group;
struct vfio_group *group;

- iommu_group = iommu_group_get(dev);
+ iommu_group = iommu_group_get(vdev->dev);
if (!iommu_group && vfio_noiommu) {
+ vdev->noiommu = 1;
/*
* With noiommu enabled, create an IOMMU group for devices that
* don't already have one, implying no IOMMU hardware/driver
* exists. Taint the kernel because we're about to give a DMA
* capable device to a user without IOMMU protection.
*/
- group = vfio_noiommu_group_alloc(dev, VFIO_NO_IOMMU);
+ group = vfio_noiommu_group_alloc(vdev, VFIO_NO_IOMMU);
if (!IS_ERR(group)) {
add_taint(TAINT_USER, LOCKDEP_STILL_OK);
- dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");
+ dev_warn(vdev->dev, "Adding kernel taint for vfio-noiommu group on device\n");
}
return group;
}
@@ -673,7 +674,7 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
mutex_lock(&vfio.group_lock);
group = vfio_group_find_from_iommu(iommu_group);
if (group) {
- if (WARN_ON(vfio_group_has_device(group, dev)))
+ if (WARN_ON(vfio_group_has_device(group, vdev->dev)))
group = ERR_PTR(-EINVAL);
else
refcount_inc(&group->drivers);
@@ -693,9 +694,9 @@ int vfio_device_set_group(struct vfio_device *device,
struct vfio_group *group;

if (type == VFIO_IOMMU)
- group = vfio_group_find_or_alloc(device->dev);
+ group = vfio_group_find_or_alloc(device);
else
- group = vfio_noiommu_group_alloc(device->dev, type);
+ group = vfio_noiommu_group_alloc(device, type);

if (IS_ERR(group))
return PTR_ERR(group);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index e90859956514..844d14839f96 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -72,6 +72,7 @@ struct vfio_device {
u8 iommufd_attached:1;
#endif
u8 cdev_opened:1;
+ u8 noiommu:1;
#ifdef CONFIG_DEBUG_FS
/*
* debug_root is a static property of the vfio_device
--
2.34.1