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    SubjectRe: [PATCH v4] virt: vmgenid: introduce driver for reinitializing RNG on VM fork
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    On 25.02.22 15:33, Jason A. Donenfeld wrote:
    > On Fri, Feb 25, 2022 at 03:18:43PM +0100, Alexander Graf wrote:
    >>> I recall this part of the old thread. From what I understood, using
    >>> "VMGENID" + "QEMUVGID" worked /well enough/, even if that wasn't
    >>> technically in-spec. Ard noted that relying on _CID like that is
    >>> technically an ACPI spec notification. So we're between one spec and
    >>> another, basically, and doing "VMGENID" + "QEMUVGID" requires fewer
    >>> changes, as mentioned, appears to work fine in my testing.
    >>>
    >>> However, with that said, I think supporting this via "VM_Gen_Counter"
    >>> would be a better eventual thing to do, but will require acks and
    >>> changes from the ACPI maintainers. Do you think you could prepare your
    >>> patch proposal above as something on-top of my tree [1]? And if you can
    >>> convince the ACPI maintainers that that's okay, then I'll happily take
    >>> the patch.
    >>
    >> Sure, let me send the ACPI patch stand alone. No need to include the
    >> VMGenID change in there.
    > That's fine. If the ACPI people take it for 5.18, then we can count on
    > it being there and adjust the vmgenid driver accordingly also for 5.18.
    >
    > I just booted up a Windows VM, and it looks like Hyper-V uses
    > "Hyper_V_Gen_Counter_V1", which is also quite long, so we can't really
    > HID match on that either.


    Yes, due to the same problem. I'd really prefer we sort out the ACPI
    matching before this goes mainline. Matching on _HID is explicitly
    discouraged in the VMGenID spec.


    Alex





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