[v2] iommufd: Enable noiommu mode for cdev

[PATCH V2 07/11] vfio: Update noiommu device detection logic for cdev

Posted by Jacob Pan 3 weeks, 4 days ago

Rework vfio_device_is_noiommu() to derive noiommu mode based on device,
group type, and configurations.

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 drivers/vfio/vfio.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 838c08077ce2..c5541967ef9b 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -127,8 +127,13 @@ static inline bool vfio_null_group_allowed(void)
 
 static inline bool vfio_device_is_noiommu(struct vfio_device *vdev)
 {
-	return IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
-	       vdev->group->type == VFIO_NO_IOMMU;
+	if (!IS_ENABLED(CONFIG_VFIO_NOIOMMU))
+		return false;
+
+	if (vfio_null_group_allowed())
+		return vdev->noiommu;
+
+	return vdev->group->type == VFIO_NO_IOMMU;
 }
 #else
 struct vfio_group;
-- 
2.34.1

Re: [PATCH V2 07/11] vfio: Update noiommu device detection logic for cdev

Posted by Mostafa Saleh 2 weeks, 2 days ago

On Thu, Mar 12, 2026 at 08:56:33AM -0700, Jacob Pan wrote:
> Rework vfio_device_is_noiommu() to derive noiommu mode based on device,
> group type, and configurations.
> 
> Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
> ---
>  drivers/vfio/vfio.h | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index 838c08077ce2..c5541967ef9b 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -127,8 +127,13 @@ static inline bool vfio_null_group_allowed(void)
>  
>  static inline bool vfio_device_is_noiommu(struct vfio_device *vdev)
>  {
> -	return IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
> -	       vdev->group->type == VFIO_NO_IOMMU;
> +	if (!IS_ENABLED(CONFIG_VFIO_NOIOMMU))
> +		return false;
> +
> +	if (vfio_null_group_allowed())
> +		return vdev->noiommu;
> +
> +	return vdev->group->type == VFIO_NO_IOMMU;

I see that noiommu is set for both, can this just be simplified to:

	return IS_ENABLED(CONFIG_VFIO_NOIOMMU) && vdev->noiommu;

Thanks,
Mostafa

>  }
>  #else
>  struct vfio_group;
> -- 
> 2.34.1
>

Re: [PATCH V2 07/11] vfio: Update noiommu device detection logic for cdev

Posted by Jacob Pan 5 days, 16 hours ago

Hi Mostafa,

On Sun, 22 Mar 2026 10:04:35 +0000
Mostafa Saleh <smostafa@google.com> wrote:

> On Thu, Mar 12, 2026 at 08:56:33AM -0700, Jacob Pan wrote:
> > Rework vfio_device_is_noiommu() to derive noiommu mode based on
> > device, group type, and configurations.
> > 
> > Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
> > ---
> >  drivers/vfio/vfio.h | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> > index 838c08077ce2..c5541967ef9b 100644
> > --- a/drivers/vfio/vfio.h
> > +++ b/drivers/vfio/vfio.h
> > @@ -127,8 +127,13 @@ static inline bool
> > vfio_null_group_allowed(void) 
> >  static inline bool vfio_device_is_noiommu(struct vfio_device *vdev)
> >  {
> > -	return IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
> > -	       vdev->group->type == VFIO_NO_IOMMU;
> > +	if (!IS_ENABLED(CONFIG_VFIO_NOIOMMU))
> > +		return false;
> > +
> > +	if (vfio_null_group_allowed())
> > +		return vdev->noiommu;
> > +
> > +	return vdev->group->type == VFIO_NO_IOMMU;  
> 
> I see that noiommu is set for both, can this just be simplified to:
> 
> 	return IS_ENABLED(CONFIG_VFIO_NOIOMMU) && vdev->noiommu;
> 
Good point, no need to check group now. will do.

Sorry for the late response.

Thanks,

Jacob