Re: [PATCH v6 05/10] iommufd: Add fault and response message definitions

[Baolu Lu]

On 6/12/24 9:52 PM, Jason Gunthorpe wrote:
> On Mon, May 27, 2024 at 12:05:12PM +0800, Lu Baolu wrote:
> > +/**
> > + * struct iommu_hwpt_pgfault - iommu page fault data
> > + * @size: sizeof(struct iommu_hwpt_pgfault)
> > + * @flags: Combination of enum iommu_hwpt_pgfault_flags
> > + * @dev_id: id of the originated device
> > + * @pasid: Process Address Space ID
> > + * @grpid: Page Request Group Index
> > + * @perm: Combination of enum iommu_hwpt_pgfault_perm
> > + * @addr: Fault address
> > + * @length: a hint of how much data the requestor is expecting to fetch. For
> > + *          example, if the PRI initiator knows it is going to do a 10MB
> > + *          transfer, it could fill in 10MB and the OS could pre-fault in
> > + *          10MB of IOVA. It's default to 0 if there's no such hint.
> > + * @cookie: kernel-managed cookie identifying a group of fault messages. The
> > + *          cookie number encoded in the last page fault of the group should
> > + *          be echoed back in the response message.
> > + */
> > +struct iommu_hwpt_pgfault {
> > +	__u32 size;
> Given we fail the system call if size is not exactly the right value
> we should probably drop it here.
>
> The ioctl to get the FD can someday specify the format of the fault
> messages if we need to upgrade. If we want to change it down the road
> then the old FD will be exactly as it is now, and the user will
> request a new format FD that only works in whatever the new way is.

Okay, sure!

Best regards,
baolu