linux-kernel - RE: [PATCH v6 2/5] iommu: Use bus iommu ops for aux related callback

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Date:   Fri, 30 Oct 2020 05:55:53 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        "Alex Williamson" <alex.williamson@...hat.com>
CC:     Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Cornelia Huck <cohuck@...hat.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>, "Zeng, Xin" <xin.zeng@...el.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: RE: [PATCH v6 2/5] iommu: Use bus iommu ops for aux related callback

> From: Lu Baolu <baolu.lu@...ux.intel.com>
> Sent: Friday, October 30, 2020 12:58 PM
> 
> The aux-domain apis were designed for macro driver where the subdevices
> are created and used inside a device driver. Use the device's bus iommu
> ops instead of that in iommu domain for various callbacks.

IIRC there are only two users on these apis. One is VFIO, and the other
is on the ARM side (not checked in yet). Jean, can you help confirm 
whether ARM-side usage still relies on aux apis even with this change?
If no, possibly they can be removed completely?

Thanks
Kevin

> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/iommu/iommu.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 6bbdd959f9f3..17f2686664db 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2913,10 +2913,11 @@
> EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled);
>   */
>  int iommu_aux_attach_device(struct iommu_domain *domain, struct device
> *dev)
>  {
> +	const struct iommu_ops *ops = dev->bus->iommu_ops;
>  	int ret = -ENODEV;
> 
> -	if (domain->ops->aux_attach_dev)
> -		ret = domain->ops->aux_attach_dev(domain, dev);
> +	if (ops && ops->aux_attach_dev)
> +		ret = ops->aux_attach_dev(domain, dev);
> 
>  	if (!ret)
>  		trace_attach_device_to_domain(dev);
> @@ -2927,8 +2928,10 @@
> EXPORT_SYMBOL_GPL(iommu_aux_attach_device);
> 
>  void iommu_aux_detach_device(struct iommu_domain *domain, struct
> device *dev)
>  {
> -	if (domain->ops->aux_detach_dev) {
> -		domain->ops->aux_detach_dev(domain, dev);
> +	const struct iommu_ops *ops = dev->bus->iommu_ops;
> +
> +	if (ops && ops->aux_detach_dev) {
> +		ops->aux_detach_dev(domain, dev);
>  		trace_detach_device_from_domain(dev);
>  	}
>  }
> @@ -2936,10 +2939,11 @@
> EXPORT_SYMBOL_GPL(iommu_aux_detach_device);
> 
>  int iommu_aux_get_pasid(struct iommu_domain *domain, struct device
> *dev)
>  {
> +	const struct iommu_ops *ops = dev->bus->iommu_ops;
>  	int ret = -ENODEV;
> 
> -	if (domain->ops->aux_get_pasid)
> -		ret = domain->ops->aux_get_pasid(domain, dev);
> +	if (ops && ops->aux_get_pasid)
> +		ret = ops->aux_get_pasid(domain, dev);
> 
>  	return ret;
>  }
> --
> 2.25.1