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Linux Plumbers Conference 2023

13–15 Nov 2023
America/New_York timezone

2023

Session

VFIO/IOMMU/PCI MC

15 Nov 2023, 09:30

Description

The PCI interconnect specification, the devices that implement it, and the system IOMMUs that provide memory and access control to them are nowadays a de-facto standard for connecting high-speed components.

Presentation materials

video
  1. 183. Improve Xeon IRQ throughput with posted interrupt
    Jacob Pan
    15/11/2023, 09:30

    Server SoCs today offer more PCIe lanes as well as the ability to stack more IO devices on a single port. Out of the box, devices such as high-speed NVMe drives can generate a significant number of interrupts at high frequencies. Due to microarchitecture choice and PCIe strong ordering requirements, limited IRQ throughput on Intel Xeon has also become a limiting factor for DMA throughput. IOPS...

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  2. 119. PCI Endpoint Subsystem Open Items Discussion
    Manivannan Sadhasivam
    15/11/2023, 10:00

    PCI Endpoint subsystem allows Linux Kernel to run on the PCI endpoint devices thereby establishing communication with the PCI host for data transfer. There are 3 open items to discuss for the PCI Endpoint subsystem:

    1. The heart of the PCI Endpoint subsystem is the Endpoint Function (EPF) driver that describes the Physical and Virtual functions inside the Endpoint device. So far 3 EPF...
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  3. 203. Non-discoverable devices in PCI devices
    Lizhi Hou (AMD), Rob Herring (Arm)
    15/11/2023, 10:30

    Modern PCI devices can expose a whole slew of hardware behind a single PCI "device". While the PCI device itself is discoverable, everything behind it (via BARs) is not. These devices aren't fixed in what downstream devices are exposed nor their configuration. There's already a solution for discovering devices and their configuration which is Devicetree. There's also already a mechanism to...

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  4. 256. IOMMU overhead optimizations and observability
    Pasha Tatashin, Yu Zhao (Google)
    15/11/2023, 11:30

    IOMMU overhead memory, which is primarily page table memory, is allocated directly from the buddy allocator, and is not charged or accounted for. Also, there is no easy way to debug IOMMU translations as there are no user interfaces that allow walking through IOMMU page tables. Below are the proposals to solve the problems.

    **Add an observability for IOMMU page table memory into...

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  5. 110. iommufd discussion
    Mr Jason Gunthorpe (NVIDIA Networking), Kevin Tian (Intel)
    15/11/2023, 12:15

    Open discussion on iommufd topics that have not been settled on the mailing list prior to the conference:

    • IOMMU based dirty tracking
    • IOMMU nested translation
    • IOMMU userspace command queue
    • Unique driver features
    • iommufd support of SVA/PRI/PASID
    • ARM interrupt handling in VMs
    • Driver enablement for iommufd features
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