linux-kernel - Re: [PATCH v2 15/28] KVM: VMX: Check CPU_BASED_{INTR,NMI}_WINDOW_EXITING in setup_vmcs

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Message-ID: <87edz5s13o.fsf@redhat.com>
Date:   Fri, 01 Jul 2022 10:12:27 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 15/28] KVM: VMX: Check
 CPU_BASED_{INTR,NMI}_WINDOW_EXITING in setup_vmcs_config()

Jim Mattson <jmattson@...gle.com> writes:

> On Wed, Jun 29, 2022 at 8:07 AM Vitaly Kuznetsov <vkuznets@...hat.com> wrote:
>>
>> CPU_BASED_{INTR,NMI}_WINDOW_EXITING controls are toggled dynamically by
>> vmx_enable_{irq,nmi}_window, handle_interrupt_window(), handle_nmi_window()
>> but setup_vmcs_config() doesn't check their existence. Add the check and
>> filter the controls out in vmx_exec_control().
>>
>> No (real) functional change intended as all existing CPUs supporting
>> VMX are supposed to have these controls.
>
> I'm pretty sure vIrtual NMIs and NMI-window exiting are not available
> on Prescott or Yonah.
>

I seemed to have questioned their existence :-) But you're right, I
should've said something like "all CPUs supported by KVM" instead (as
pre-patch KVM toggles these controls unconditionally).

>> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> Reviewed-by: Jim Mattson <jmattson@...gle.com>
>

Thanks!

-- 
Vitaly