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    SubjectRe: [PATCH v8 2/5] x86/tdx: Add TDX Guest event notify interrupt support
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    On Mon, 2022-06-20 at 08:44 -0700, Sathyanarayanan Kuppuswamy wrote:
    > I agree that event notification is currently only used for attestation. But I
    > think in future there could be other use cases for it. 
    >

    We have TDVMCALL<Service> in GHCI 1.5. It allows specifying the vector. I
    don't know whether there's any future case that still needs
    SetupEventNotifyInterrupt.

    > If the intention is just
    > to use it for attestation, then we can just modify the GetQuote TDVMCALL to pass
    > the vector address, and there is no need for new TDVMCALL.

    The TDVMCALL<Service> in GHCI 1.5 actually supports specifying the vector. It
    currently neither clearly says "the VMM should inject event to the vCPU on which
    the TDVMCALL<Service> is called", nor it allows specifying which vCPU to inject.
    Assuming we can lobby (I am already lobbying, actually) to make either way, in
    fact I think it can be used as IRQ way (like I described in my first reply).

    I once lobbied to completely remove GetQuote (and SetupEventNotifyInterrupt)
    from GHCI 1.0 and move TDVMCALL<Service> from GHCI 1.5 to 1.0, and define a new
    sub-service for attestation -- GetQuote will be one command then, and we can
    define more attestation related commands (which is likely) when needed. I
    believe using TDVMCALL<Service> for GetQuote can actually allow kernel to use
    IRQ way, but doesn't need a system vector. But this wasn't successful.


    --
    Thanks,
    -Kai


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