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    SubjectRe: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection
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    On Sun, Nov 08 2020 at 22:09, David Woodhouse wrote:

    >> On Fri, Nov 06 2020 at 09:14, Jason Gunthorpe wrote:
    >>> On Fri, Nov 06, 2020 at 09:48:34AM +0000, Tian, Kevin wrote:
    >>> For instance you could put a "disable IMS" flag in the ACPI tables, in
    >>> the config space of the emuulated root port, or any other areas that
    >>> clearly belong to the platform.
    >>>
    >>> The OS logic would be
    >>> - If no IMS information found then use IMS (Bare metal)
    >>> - If the IMS disable flag is found then
    >>> - If (future) hypercall available and the OS knows how to use it
    >>> then use IMS
    >>> - If no hypercall found, or no OS knowledge, fail IMS
    >>
    >> That does not work because an older hypervisor would not have that
    >> disable flag and the guest kernel would assume to be on bare metal (if
    >> no other indicators are there).
    >
    > In the absence of a forward-thinking design from Intel perhaps we could

    Just to be fair the AMD interrupt remapping is not any better in that
    regard.

    Thanks,

    tglx

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