RE: [PATCH v3 3/4] vfio: Add VFIO_DEVICE_PASID_[AT|DE]TACH_IOMMUFD_PT

From: Liu, Yi L yi.l.liu@intel.com Sent: Thursday, September 12, 2024 9:17 PM

+/*

• • VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT - _IOW(VFIO_TYPE,

VFIO_BASE + 21,

• • 			      struct
    

vfio_device_pasid_attach_iommufd_pt)

• • @argsz: User filled size of this data.
• • @flags: Must be 0.
• • @pasid: The pasid to be attached.
• • @pt_id: Input the target id which can represent an ioas or a hwpt

• • allocated via iommufd subsystem.
    

• • Output the input ioas id or the attached hwpt id which could
    

• • be the specified hwpt itself or a hwpt automatically created
    

• • for the specified ioas by kernel during the attachment.
    

• • Associate a pasid with an address space within the bound iommufd.

Undo by

• • VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT or device fd close. This is

only allowed

• • on cdev fds.
• • If a pasid is currently attached to a valid hwpt, without doing a
• • VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT, a second
• • VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT ioctl passing in another

hwpt id is

• • allowed. This action, also known as a hwpt replacement, will replace the
• • pasid's currently attached hwpt with a new hwpt corresponding to the

given

• • @pt_id.
• • Return: 0 on success, -errno on failure.
• */

+struct vfio_device_pasid_attach_iommufd_pt {

• __u32 argsz;
• __u32 flags;
• __u32 pasid;
• __u32 pt_id;

+};

+#define VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT _IO(VFIO_TYPE, VFIO_BASE + 21)

Not sure whether this was discussed before. Does it make sense to reuse the existing VFIO_DEVICE_ATTACH_IOMMUFD_PT by introducing a new pasid field and a new flag bit?