Re: [RFC 00/18] vfio: Adopt iommufd

[Yi Liu]

Hi Zhangfei,

On 2022/5/11 22:17, zhangfei.gao@foxmail.com wrote:
> On 2022/5/10 下午10:08, Yi Liu wrote:
> > On 2022/5/10 20:45, Jason Gunthorpe wrote:
> > > On Tue, May 10, 2022 at 08:35:00PM +0800, Zhangfei Gao wrote:
> > > > Thanks Yi and Eric,
> > > > Then will wait for the updated iommufd kernel for the PCI MMIO region.
> > > >
> > > > Another question,
> > > > How to get the iommu_domain in the ioctl.
> > >
> > > The ID of the iommu_domain (called the hwpt) it should be returned by
> > > the vfio attach ioctl.
> >
> > yes, hwpt_id is returned by the vfio attach ioctl and recorded in
> > qemu. You can query page table related capabilities with this id.
> >
> > https://lore.kernel.org/kvm/20220414104710.28534-16-yi.l.liu@intel.com/
> Thanks Yi,
>
> Do we use iommufd_hw_pagetable_from_id in kernel?
>
> The qemu send hwpt_id via ioctl.
> Currently VFIOIOMMUFDContainer has hwpt_list,
> Which member is good to save hwpt_id, IOMMUTLBEntry?

currently, we don't make use of hwpt yet in the version we have
in the qemu branch. I have a change to make use of it. Also, it
would be used in future for nested translation setup and also
dirty page bit support query for a given domain.

> In kernel ioctl: iommufd_vfio_ioctl
> @dev: Device to get an iommu_domain for
> iommufd_hw_pagetable_from_id(struct iommufd_ctx *ictx, u32 pt_id, struct 
> device *dev)
> But iommufd_vfio_ioctl seems no para dev?

there is. you can look at the vfio_group_set_iommufd(), it loops the
device_list provided by vfio. And the device info is passed to iommufd.

> Thanks

--
Regards,
Yi Liu