Re: [PATCH v2 0/6] IOMMUFD: Deliver IO page faults to user space

[Baolu Lu]

On 2023/11/29 17:08, Shameerali Kolothum Thodi wrote:
> > -----Original Message-----
> > From: Lu Baolu [mailto:baolu.lu@xxxxxxxxxxxxxxx]
> > Sent: 26 October 2023 03:49
> > To: Jason Gunthorpe <jgg@xxxxxxxx>; Kevin Tian <kevin.tian@xxxxxxxxx>;
> > Joerg Roedel <joro@xxxxxxxxxx>; Will Deacon <will@xxxxxxxxxx>; Robin
> > Murphy <robin.murphy@xxxxxxx>; Jean-Philippe Brucker
> > <jean-philippe@xxxxxxxxxx>; Nicolin Chen <nicolinc@xxxxxxxxxx>; Yi Liu
> > <yi.l.liu@xxxxxxxxx>; Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > Cc: iommu@xxxxxxxxxxxxxxx; linux-kselftest@xxxxxxxxxxxxxxx;
> > virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Lu
> > Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Subject: [PATCH v2 0/6] IOMMUFD: Deliver IO page faults to user space
> >
> > Hi folks,
> >
> > This series implements the functionality of delivering IO page faults to
> > user space through the IOMMUFD framework for nested translation. Nested
> > translation is a hardware feature that supports two-stage translation
> > tables for IOMMU. The second-stage translation table is managed by the
> > host VMM, while the first-stage translation table is owned by user
> > space. This allows user space to control the IOMMU mappings for its
> > devices.
> >
> > When an IO page fault occurs on the first-stage translation table, the
> > IOMMU hardware can deliver the page fault to user space through the
> > IOMMUFD framework. User space can then handle the page fault and
> > respond
> > to the device top-down through the IOMMUFD. This allows user space to
> > implement its own IO page fault handling policies.
> >
> > User space indicates its capability of handling IO page faults by
> > setting the IOMMU_HWPT_ALLOC_IOPF_CAPABLE flag when allocating a
> > hardware page table (HWPT). IOMMUFD will then set up its infrastructure
> > for page fault delivery. On a successful return of HWPT allocation, the
> > user can retrieve and respond to page faults by reading and writing to
> > the file descriptor (FD) returned in out_fault_fd.
> >
> > The iommu selftest framework has been updated to test the IO page fault
> > delivery and response functionality.
> >
> > This series is based on the latest implementation of nested translation
> > under discussion [1] and the page fault handling framework refactoring in
> > the IOMMU core [2].
> >
> > The series and related patches are available on GitHub: [3]
> >
> > [1]
> > https://lore.kernel.org/linux-iommu/20230921075138.124099-1-yi.l.liu@int
> > el.com/
> > [2]
> > https://lore.kernel.org/linux-iommu/20230928042734.16134-1-baolu.lu@li
> > nux.intel.com/
> > [3]
> > https://github.com/LuBaolu/intel-iommu/commits/iommufd-io-pgfault-deliv
> > ery-v2
>
> Hi Baolu,

Hi Shameer,

> Do you have a corresponding Qemu git to share? I could give it a spin on our ARM
> platform. Please let me know.

This version of the series is tested by the iommufd selftest. We are in
process of developing the QEMU code. I will provide the repo link after
we complete it.

Best regards,
baolu