linux-kernel - Re: [PATCH 1/2] KVM: VMX: Don't advertise EPT switching if EPT itself is not exposed

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Date:   Tue, 17 Oct 2017 11:12:52 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Jim Mattson <jmattson@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH 1/2] KVM: VMX: Don't advertise EPT switching if EPT itself
 is not exposed

2017-10-17 1:16 GMT+08:00 Jim Mattson <jmattson@...gle.com>:
> Does it still make sense to advertise "Enable VM Functions" in the
> secondary processor-based VM-execution controls if we don't actually
> support any VM Functions?

Will do in v2. Thanks for your review.

Regards,
Wanpeng Li

>
> On Sat, Oct 14, 2017 at 7:31 PM, Wanpeng Li <kernellwp@...il.com> wrote:
>> From: Wanpeng Li <wanpeng.li@...mail.com>
>>
>> EPT switching is advertised unconditionally since it is emulated, however, it can
>> be treated as an extended feature for EPT, it should be not advertised if EPT itself
>> is not exposed. This patch fixes it.
>>
>> Cc: Paolo Bonzini <pbonzini@...hat.com>
>> Cc: Radim Krčmář <rkrcmar@...hat.com>
>> Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
>> ---
>>  arch/x86/kvm/vmx.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index c460b0b..3644540 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -2842,8 +2842,9 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
>>                  * Advertise EPTP switching unconditionally
>>                  * since we emulate it
>>                  */
>> -               vmx->nested.nested_vmx_vmfunc_controls =
>> -                       VMX_VMFUNC_EPTP_SWITCHING;
>> +               if (enable_ept)
>> +                       vmx->nested.nested_vmx_vmfunc_controls =
>> +                               VMX_VMFUNC_EPTP_SWITCHING;
>>         }
>>
>>         /*
>> --
>> 2.7.4
>>