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    SubjectRe: [PATCH 6/6] KVM: VMX: enable IPI virtualization
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    On 7/19/2021 4:32 AM, Paolo Bonzini wrote:
    > On 17/07/21 05:55, Zeng Guang wrote:
    >>>> +    if (vmx->ipiv_active)
    >>>> +        install_pid(vmx);
    >>> This should be if (enable_ipiv) instead, I think.
    >>>
    >>> In fact, in all other places that are using vmx->ipiv_active, you can
    >>> actually replace it with enable_ipiv; they are all reached only with
    >>> kvm_vcpu_apicv_active(vcpu) == true.
    >>>
    >> enable_ipiv as a global variable indicates the hardware capability to
    >> enable IPIv. Each VM may have different IPIv configuration according to
    >> kvm_vcpu_apicv_active status. So we use ipiv_active per VM to enclose
    >> IPIv related operations.
    > Understood, but in practice all uses of vmx->ipiv_active are guarded by
    > kvm_vcpu_apicv_active so they are always reached with vmx->ipiv_active
    > == enable_ipiv.
    >
    > The one above instead seems wrong and should just use enable_ipiv.
    enable_ipiv associate with "IPI virtualization" setting in tertiary exec
    controls and
    enable_apicv which depends on cpu_has_vmx_apicv(). kvm_vcpu_apicv_active
    still
    can be false even if enable_ipiv is true, e.g. in case irqchip not
    emulated in kernel.

    Though it's ok to use enable_ipiv here, vmcs setup succeed for IPIv but
    it won't take into effect as
    false kvm_vcpu_apicv_active runtime disable “IPI virtualization" for VM
    in this case and
    leads vmx->ipiv_active become false as well. So vmx->ipiv_active is more
    accurate to reflect
    runtime IPIv status.
    > Paolo
    >

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