iommu/tegra241-cmdqv: Fix initialization and uAPI related to HYP_OWN

[PATCH 2/2] iommu/tegra241-cmdqv: Update uAPI to clarify HYP_OWN requirement

Posted by Nicolin Chen 3 weeks, 4 days ago

From hardware implementation perspective, a guest tegra241-cmdqv hardware
is different than the host hardware:
 - Host HW is backed by a VINTF (HYP_OWN=1)
 - Guest HW is backed by a VINTF (HYP_OWN=0)

The kernel driver has an implementation requirement of the HYP_OWN bit in
the VM. So, VMM must follow that to allow the same copy of Linux to work.

Add this requirement to the uAPI, which is currently missing.

Fixes: 4dc0d12474f9 ("iommu/tegra241-cmdqv: Add user-space use support")
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 include/uapi/linux/iommufd.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 1dafbc552d37d..f63edbe71d542 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -1052,6 +1052,11 @@ struct iommu_fault_alloc {
 enum iommu_viommu_type {
 	IOMMU_VIOMMU_TYPE_DEFAULT = 0,
 	IOMMU_VIOMMU_TYPE_ARM_SMMUV3 = 1,
+	/*
+	 * TEGRA241_CMDQV requirements (otherwise, VCMDQs will not work)
+	 * - Kernel will allocate a VINTF (HYP_OWN=0) to back this VIOMMU. So,
+	 *   VMM must wire the HYP_OWN bit to 0 in guest VINTF_CONFIG register
+	 */
 	IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV = 2,
 };
 
-- 
2.43.0

Re: [PATCH 2/2] iommu/tegra241-cmdqv: Update uAPI to clarify HYP_OWN requirement

Posted by Eric Auger 2 weeks ago


On 3/13/26 1:36 AM, Nicolin Chen wrote:
> From hardware implementation perspective, a guest tegra241-cmdqv hardware
> is different than the host hardware:
>  - Host HW is backed by a VINTF (HYP_OWN=1)
>  - Guest HW is backed by a VINTF (HYP_OWN=0)
>
> The kernel driver has an implementation requirement of the HYP_OWN bit in
> the VM. So, VMM must follow that to allow the same copy of Linux to work.
>
> Add this requirement to the uAPI, which is currently missing.
>
> Fixes: 4dc0d12474f9 ("iommu/tegra241-cmdqv: Add user-space use support")
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> ---
>  include/uapi/linux/iommufd.h | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index 1dafbc552d37d..f63edbe71d542 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -1052,6 +1052,11 @@ struct iommu_fault_alloc {
>  enum iommu_viommu_type {
>  	IOMMU_VIOMMU_TYPE_DEFAULT = 0,
>  	IOMMU_VIOMMU_TYPE_ARM_SMMUV3 = 1,
> +	/*
> +	 * TEGRA241_CMDQV requirements (otherwise, VCMDQs will not work)
> +	 * - Kernel will allocate a VINTF (HYP_OWN=0) to back this VIOMMU. So,
> +	 *   VMM must wire the HYP_OWN bit to 0 in guest VINTF_CONFIG register
> +	 */
>  	IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV = 2,
>  };
>

Re: [PATCH 2/2] iommu/tegra241-cmdqv: Update uAPI to clarify HYP_OWN requirement

Posted by Will Deacon 2 weeks, 4 days ago

On Thu, Mar 12, 2026 at 05:36:35PM -0700, Nicolin Chen wrote:
> From hardware implementation perspective, a guest tegra241-cmdqv hardware
> is different than the host hardware:
>  - Host HW is backed by a VINTF (HYP_OWN=1)
>  - Guest HW is backed by a VINTF (HYP_OWN=0)
> 
> The kernel driver has an implementation requirement of the HYP_OWN bit in
> the VM. So, VMM must follow that to allow the same copy of Linux to work.
> 
> Add this requirement to the uAPI, which is currently missing.
> 
> Fixes: 4dc0d12474f9 ("iommu/tegra241-cmdqv: Add user-space use support")
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  include/uapi/linux/iommufd.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index 1dafbc552d37d..f63edbe71d542 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -1052,6 +1052,11 @@ struct iommu_fault_alloc {
>  enum iommu_viommu_type {
>  	IOMMU_VIOMMU_TYPE_DEFAULT = 0,
>  	IOMMU_VIOMMU_TYPE_ARM_SMMUV3 = 1,
> +	/*
> +	 * TEGRA241_CMDQV requirements (otherwise, VCMDQs will not work)
> +	 * - Kernel will allocate a VINTF (HYP_OWN=0) to back this VIOMMU. So,
> +	 *   VMM must wire the HYP_OWN bit to 0 in guest VINTF_CONFIG register
> +	 */
>  	IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV = 2,
>  };

Jason, are you happy with this one?

Will

Re: [PATCH 2/2] iommu/tegra241-cmdqv: Update uAPI to clarify HYP_OWN requirement

Posted by Jason Gunthorpe 2 weeks ago

On Thu, Mar 19, 2026 at 02:47:13PM +0000, Will Deacon wrote:
> On Thu, Mar 12, 2026 at 05:36:35PM -0700, Nicolin Chen wrote:
> > From hardware implementation perspective, a guest tegra241-cmdqv hardware
> > is different than the host hardware:
> >  - Host HW is backed by a VINTF (HYP_OWN=1)
> >  - Guest HW is backed by a VINTF (HYP_OWN=0)
> > 
> > The kernel driver has an implementation requirement of the HYP_OWN bit in
> > the VM. So, VMM must follow that to allow the same copy of Linux to work.
> > 
> > Add this requirement to the uAPI, which is currently missing.
> > 
> > Fixes: 4dc0d12474f9 ("iommu/tegra241-cmdqv: Add user-space use support")
> > Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> > ---
> >  include/uapi/linux/iommufd.h | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> > index 1dafbc552d37d..f63edbe71d542 100644
> > --- a/include/uapi/linux/iommufd.h
> > +++ b/include/uapi/linux/iommufd.h
> > @@ -1052,6 +1052,11 @@ struct iommu_fault_alloc {
> >  enum iommu_viommu_type {
> >  	IOMMU_VIOMMU_TYPE_DEFAULT = 0,
> >  	IOMMU_VIOMMU_TYPE_ARM_SMMUV3 = 1,
> > +	/*
> > +	 * TEGRA241_CMDQV requirements (otherwise, VCMDQs will not work)
> > +	 * - Kernel will allocate a VINTF (HYP_OWN=0) to back this VIOMMU. So,
> > +	 *   VMM must wire the HYP_OWN bit to 0 in guest VINTF_CONFIG register
> > +	 */
> >  	IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV = 2,
> >  };
> 
> Jason, are you happy with this one?

Yes, please pick up the series

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason