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

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2023/11/29 17:08, Shameerali Kolothum Thodi wrote:
> 
> 
>> -----Original Message-----
>> From: Lu Baolu [mailto:baolu.lu@linux.intel.com]
>> Sent: 26 October 2023 03:49
>> To: Jason Gunthorpe <jgg@ziepe.ca>; Kevin Tian <kevin.tian@intel.com>;
>> Joerg Roedel <joro@8bytes.org>; Will Deacon <will@kernel.org>; Robin
>> Murphy <robin.murphy@arm.com>; Jean-Philippe Brucker
>> <jean-philippe@linaro.org>; Nicolin Chen <nicolinc@nvidia.com>; Yi Liu
>> <yi.l.liu@intel.com>; Jacob Pan <jacob.jun.pan@linux.intel.com>
>> Cc: iommu@lists.linux.dev; linux-kselftest@vger.kernel.org;
>> virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org; Lu
>> Baolu <baolu.lu@linux.intel.com>
>> 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