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    SubjectRe: [PATCH v4 4/6] KVM: X86: Implement PV IPIs send hypercall
    On Mon, 23 Jul 2018 at 14:19, Paolo Bonzini <pbonzini@redhat.com> wrote:
    >
    > On 23/07/2018 08:10, Wanpeng Li wrote:
    > >>> On 20/07/2018 18:28, Wanpeng Li wrote:
    > >>>> +a0: ipi_bitmap low 64 bits
    > >>>> +a1: ipi_bitmap high 64 bits
    > >>>> +a2: the lowest APIC ID in bitmap
    > >>>> +a3: APIC ICR
    > >>>> +
    > >>>> +The hypercall lets a guest send multicast IPIs at most can handle
    > >>>> +128 vCPUs per hypercall on 64-bit machines and 64 vCPUs per hypercall
    > >>>> +on 32-bit machines.
    > >>>> +
    > >>>> +Returns 0 if successfully delivery the IPIs and 1 if discarded.
    > >>> This description does not mention what happens in 32-bit mode.
    > > Sorry, I think I mentioned "64 vCPUs per hypercall on 32-bit machines" above.
    >
    > Yes, but the description of a0 and a1 is not accurate. Something like
    >
    > a0: lower part of the bitmap of destination APIC IDs
    > a1: higher part of the bitmap of destination APIC IDs
    > ....
    >
    > The hypercall lets a guest send multicast IPIs, with at most 128
    > 128 destinations per hypercall in 64-bit mode and 64 vCPUs per
    > hypercall in 32-bit mode. The destinations are represented by a bitmap
    > contained in the first two arguments (a0 and a1). Bit 0 of a0
    > corresponds to the APIC ID in the third argument (a2), bit 1 corresponds
    > to the APIC ID a2+1, and so on.

    Thanks to the great description, I will fold this to the next version.

    Regards,
    Wanpeng Li

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