Re: [PATCH v4 1/4] iommufd/device: Associate a kvm pointer to iommufd_device

[Jason Gunthorpe]

On Mon, Apr 27, 2026 at 11:40:02AM +0530, Aneesh Kumar K.V (Arm) wrote:
> From: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> 
> Add a struct kvm * to iommufd_device_bind() fn and associate it
> with idev if bind is successful.
> 
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> [nicolinc: fix build error in iommufd_test_mock_domain()]
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@xxxxxxxxxx>
> ---
>  drivers/iommu/iommufd/device.c          | 5 ++++-
>  drivers/iommu/iommufd/iommufd_private.h | 2 ++
>  drivers/iommu/iommufd/selftest.c        | 2 +-
>  drivers/vfio/iommufd.c                  | 2 +-
>  include/linux/iommufd.h                 | 4 +++-
>  5 files changed, 11 insertions(+), 4 deletions(-)

> diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> index 344d620cdecc..453fbceb9219 100644
> --- a/drivers/iommu/iommufd/device.c
> +++ b/drivers/iommu/iommufd/device.c
> @@ -203,6 +203,7 @@ void iommufd_device_destroy(struct iommufd_object *obj)
>   * iommufd_device_bind - Bind a physical device to an iommu fd
>   * @ictx: iommufd file descriptor
>   * @dev: Pointer to a physical device struct
> + * @kvm: Pointer to struct kvm if device belongs to a KVM VM
>   * @id: Output ID number to return to userspace for this device
>   *
>   * A successful bind establishes an ownership over the device and returns
> @@ -216,7 +217,8 @@ void iommufd_device_destroy(struct iommufd_object *obj)
>   * The caller must undo this with iommufd_device_unbind()
>   */
>  struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
> -					   struct device *dev, u32 *id)
> +					   struct device *dev, struct kvm *kvm,
> +					   u32 *id)

I thought we were trying to get away from struct kvm?

https://lore.kernel.org/all/adf29Rn7q9Db0hxc@xxxxxxxxxx/

Ie this should be a 'struct file *kvm_fd'

?

Though I am wondering how practical it is to do this at this moment :\

Maybe ask Paolo how his series is going?

>  {
>  	struct iommufd_device *idev;
>  	struct iommufd_group *igroup;
> @@ -266,6 +268,7 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
>  	if (!iommufd_selftest_is_mock_dev(dev))
>  		iommufd_ctx_get(ictx);
>  	idev->dev = dev;
> +	idev->kvm = kvm;

If we do that then I'd take a file refcount here ^^^

And then put it back when the idev is freed

That makes the lifecycle robust.

Jason