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

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Date: Sun, 14 Jan 2024 21:13:19 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Joel Granados <j.granados@...sung.com>
Cc: baolu.lu@...ux.intel.com, Jason Gunthorpe <jgg@...pe.ca>,
 Kevin Tian <kevin.tian@...el.com>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 Jean-Philippe Brucker <jean-philippe@...aro.org>,
 Nicolin Chen <nicolinc@...dia.com>, Yi Liu <yi.l.liu@...el.com>,
 Jacob Pan <jacob.jun.pan@...ux.intel.com>, iommu@...ts.linux.dev,
 linux-kselftest@...r.kernel.org, virtualization@...ts.linux-foundation.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/6] IOMMUFD: Deliver IO page faults to user space

On 2024/1/13 5:56, Joel Granados wrote:
> On Thu, Oct 26, 2023 at 10:49:24AM +0800, Lu Baolu wrote:
>> 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@intel.com/
>> [2]https://lore.kernel.org/linux-iommu/20230928042734.16134-1-baolu.lu@linux.intel.com/
>> [3]https://github.com/LuBaolu/intel-iommu/commits/iommufd-io-pgfault-delivery-v2
> I was working with this branch that included Yi Liu's
> wip/iommufd_nesting branch. Now Yi Lui has updated his work in this post
> https://lore.kernel.org/all/20240102143834.146165-1-yi.l.liu@intel.com.
> Is there an updated version of the page fault work that is rebased on
> top of Liu's new version?

Yes. I am preparing the new version and will post it for discussion
after the merge window.

Best regards,
baolu