Re: [Intel-gfx] [PATCH v9 04/25] vfio: Accept vfio device file in the KVM facing kAPI

[Eric Auger <eric.auger@redhat.com>]

Hi Yi,

On 4/1/23 17:18, Yi Liu wrote:
> This makes the vfio file kAPIs to accept vfio device files, also a
> preparation for vfio device cdev support.
>
> For the kvm set with vfio device file, kvm pointer is stored in struct
> vfio_device_file, and use kvm_ref_lock to protect kvm set and kvm
> pointer usage within VFIO. This kvm pointer will be set to vfio_device
> after device file is bound to iommufd in the cdev path.
>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Tested-by: Terrence Xu <terrence.xu@intel.com>
> Tested-by: Nicolin Chen <nicolinc@nvidia.com>
> Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
> Tested-by: Yanting Jiang <yanting.jiang@intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric
> ---
>  drivers/vfio/vfio.h      |  2 ++
>  drivers/vfio/vfio_main.c | 18 ++++++++++++++++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index 56ad127ac618..e4672d91a6f7 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -18,6 +18,8 @@ struct vfio_container;
>  
>  struct vfio_device_file {
>  	struct vfio_device *device;
> +	spinlock_t kvm_ref_lock; /* protect kvm field */
> +	struct kvm *kvm;
>  };
>  
>  void vfio_device_put_registration(struct vfio_device *device);
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 748bde4d74d9..cb543791b28b 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -414,6 +414,7 @@ vfio_allocate_device_file(struct vfio_device *device)
>  		return ERR_PTR(-ENOMEM);
>  
>  	df->device = device;
> +	spin_lock_init(&df->kvm_ref_lock);
>  
>  	return df;
>  }
> @@ -1246,6 +1247,20 @@ bool vfio_file_enforced_coherent(struct file *file)
>  }
>  EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);
>  
> +static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm)
> +{
> +	struct vfio_device_file *df = file->private_data;
> +
> +	/*
> +	 * The kvm is first recorded in the vfio_device_file, and will
> +	 * be propagated to vfio_device::kvm when the file is bound to
> +	 * iommufd successfully in the vfio device cdev path.
> +	 */
> +	spin_lock(&df->kvm_ref_lock);
> +	df->kvm = kvm;
> +	spin_unlock(&df->kvm_ref_lock);
> +}
> +
>  /**
>   * vfio_file_set_kvm - Link a kvm with VFIO drivers
>   * @file: VFIO group file or VFIO device file
> @@ -1259,6 +1274,9 @@ void vfio_file_set_kvm(struct file *file, struct kvm *kvm)
>  	group = vfio_group_from_file(file);
>  	if (group)
>  		vfio_group_set_kvm(group, kvm);
> +
> +	if (vfio_device_from_file(file))
> +		vfio_device_file_set_kvm(file, kvm);
>  }
>  EXPORT_SYMBOL_GPL(vfio_file_set_kvm);
>