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

[Jason Gunthorpe]

On Wed, Apr 29, 2026 at 07:22:46PM +0530, Aneesh Kumar K.V wrote:
> 
> Jason Gunthorpe <jgg@xxxxxxxx> writes:
> 
> > On Tue, Apr 28, 2026 at 05:31:04PM +0530, Aneesh Kumar K.V wrote:
> >> > 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 :\
> >> >
> >> 
> >> Should we also switch 
> >> 
> >> modified   drivers/vfio/vfio.h
> >> @@ -22,8 +22,8 @@ struct vfio_device_file {
> >>  
> >>  	u8 access_granted;
> >>  	u32 devid; /* only valid when iommufd is valid */
> >> -	spinlock_t kvm_ref_lock; /* protect kvm field */
> >> -	struct kvm *kvm;
> >> +	spinlock_t kvm_ref_lock; /* protect kvm_file */
> >> +	struct file *kvm_file;
> >>  	struct iommufd_ctx *iommufd; /* protected by struct vfio_device_set::lock */
> >>  };
> >>  
> >> @@ -88,7 +88,7 @@ struct vfio_group {
> >>  #endif
> >>  	enum vfio_group_type		type;
> >>  	struct mutex			group_lock;
> >> -	struct kvm			*kvm;
> >> +	struct file			*kvm_file;
> >>  	struct file			*opened_file;
> >>  	struct blocking_notifier_head	notifier;
> >>  	struct iommufd_ctx		*iommufd;
> >
> > Ideally, yes everything outside kvm should just use the struct file
> > and there should be quite narrow places where you do some kvm
> > operation on it.
> >  
> >> ie,
> >> KVM_CREATE_DEVICE with KVM_DEV_TYPE_VFIO still use kvm->users_count,
> >> KVM_DEV_VFIO_FILE_ADD -> will switch to get_file(kvm->_file);
> >> and VFIO_DEVICE_BIND_IOMMUFD -> will switch to get_file(df->kvm_file)
> >> 
> >> > Maybe ask Paolo how his series is going?
> >
> > I thought the above is what Paolo's series was going after?
> >
> 
> Hi Paolo,
> 
> Could you please take a look at this? I’ve tried to document the
> reference count details and hope I’ve captured everything correctly, but
> I’d appreciate your review to make sure I haven’t missed anything.

Reminder?

Jason