Re: [PATCH v8 0/5] vfio-pci support pasid attach/detach

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Mar 17, 2025 at 03:25:18PM +0800, Yi Liu wrote:
> On 2025/3/14 22:48, Alex Williamson wrote:
> > On Thu, 13 Mar 2025 05:47:48 -0700
> > Yi Liu <yi.l.liu@intel.com> wrote:
> > 
> > > This series introduces the PASID attach/detach user APIs (uAPIs) that
> > > allow userspace to attach or detach a device's PASID to or from a specified
> > > IOAS/hwpt. Currently, only the vfio-pci driver is enabled in this series.
> > > 
> > > Following this update, PASID-capable devices bound to vfio-pci can report
> > > PASID capabilities to userspace and virtual machines (VMs), facilitating
> > > PASID use cases such as Shared Virtual Addressing (SVA). In discussions
> > > about reporting the virtual PASID (vPASID) to VMs [1], it was agreed that
> > > the userspace virtual machine monitor (VMM) will synthesize the vPASID
> > > capability. The VMM must identify a suitable location to insert the vPASID
> > > capability, including handling hidden bits for certain devices. However,
> > > this responsibility lies with userspace and is not the focus of this series.
> > > 
> > > This series begins by adding helpers for PASID attachment in the vfio core,
> > > then extends the device character device (cdev) attach/detach ioctls to
> > > support PASID attach/detach operations. At the conclusion of this series,
> > > the IOMMU_GET_HW_INFO ioctl is extended to report PCI PASID capabilities
> > > to userspace. Userspace should verify this capability before utilizing any
> > > PASID-related uAPIs provided by VFIO, as agreed in [2]. This series depends
> > > on the iommufd PASID attach/detach series [3].
> > > 
> > > The complete code is available at [4] and has been tested with a modified
> > > QEMU branch [5].
> > 
> > What's missing for this to go in and which tree will take it?  At a
> > glance it seems like 4/ needs a PCI sign-off and 5/ needs an IOMMUFD
> > sign-off.  Thanks,
> 
> Hi Alex,
> 
> yep, I just looped Bjorn in patch 4. While for patch 5, Jason is cced. I
> thought this may need to be taken together with the iommufd pasid
> series [1] due to dependency. Jason also mentioned this in the before [2].
> It might be a shared tree from both of you I guess. :)

Yes, it all has to go together.. Everything is waiting on this:

> [1] https://lore.kernel.org/linux-iommu/20250313123532.103522-1-yi.l.liu@intel.com/

Which will hopefully be done in a few days??

Jason