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Date: Wed, 27 Sep 2023 10:49:29 +0800
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Subject: Re: [RFC 3/8] iommufd: Support attach/replace hwpt per pasid
Content-Language: en-US
To: Yi Liu <yi.l.liu@intel.com>, joro@8bytes.org, alex.williamson@redhat.com,
 jgg@nvidia.com, kevin.tian@intel.com, robin.murphy@arm.com
References: <20230926092651.17041-1-yi.l.liu@intel.com>
 <20230926092651.17041-4-yi.l.liu@intel.com>
From: Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <20230926092651.17041-4-yi.l.liu@intel.com>
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On 9/26/23 5:26 PM, Yi Liu wrote:
> From: Kevin Tian<kevin.tian@intel.com>
> 
> This introduces three APIs for device drivers to manage pasid attach/
> replace/detach.
> 
>      int iommufd_device_pasid_attach(struct iommufd_device *idev,
> 				    u32 pasid, u32 *pt_id);
>      int iommufd_device_pasid_replace(struct iommufd_device *idev,
> 				     u32 pasid, u32 *pt_id);
>      void iommufd_device_pasid_detach(struct iommufd_device *idev,
> 				     u32 pasid);

I am a bit puzzled. Do we really need both attach and replace interfaces
to install a hwpt onto a pasid on device? The IOMMUFD already tracks the
connections between hwpt and {device, pasid}, so it could easily call
the right iommu interfaces (attach vs. replace). Perhaps I overlooked
previous discussion on this.

Best regards,
baolu