Re: [RFC 3/8] iommufd: Support attach/replace hwpt per pasid

On 9/26/23 5:26 PM, Yi Liu wrote:

From: Kevin Tiankevin.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