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    Subject[PATCH 0/6] VMD MSI Remapping Bypass
    Date
    The Intel Volume Management Device acts similar to a PCI-to-PCI bridge in that
    it changes downstream devices' requester-ids to its own. As VMD supports PCIe
    devices, it has its own MSI/X table and transmits child device MSI/X by
    remapping child device MSI/X and handling like a demultiplexer.

    Some newer VMD devices (Icelake Server and client) have an option to bypass the
    VMD MSI/X remapping table. This allows for better performance scaling as the
    child device MSI/X won't be limited by VMD's MSI/X count and IRQ handler.

    It's expected that most users don't want MSI/X remapping when they can get
    better performance without this limitation. This set includes some long overdue
    cleanup of overgrown VMD code and introduces the MSI/X remapping disable.

    Applies on top of e3beca48a45b ("irqdomain/treewide: Keep firmware node
    unconditionally allocated") and ec0160891e38 ("irqdomain/treewide: Free
    firmware node after domain removal") in tip/urgent


    Jon Derrick (6):
    PCI: vmd: Create physical offset helper
    PCI: vmd: Create bus offset configuration helper
    PCI: vmd: Create IRQ Domain configuration helper
    PCI: vmd: Create IRQ allocation helper
    x86/apic/msi: Use Real PCI DMA device when configuring IRTE
    PCI: vmd: Disable MSI/X remapping when possible

    arch/x86/kernel/apic/msi.c | 2 +-
    drivers/pci/controller/vmd.c | 344 +++++++++++++++++++++++------------
    2 files changed, 224 insertions(+), 122 deletions(-)


    base-commit: ec0160891e387f4771f953b888b1fe951398e5d9
    --
    2.27.0

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