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From: David Matlack <dmatlack@google.com>
Date: Mon, 28 Nov 2016 13:11:55 -0800
Message-ID: <CALzav=cHZJcasS+aSYmuXv-RhO4AAUFTNOYDyViaoay19=rOeQ@mail.gmail.com>
Subject: Re: [PATCH 1/4] KVM: nVMX: support restore of VMX capability MSRs
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm list <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jim Mattson <jmattson@google.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>
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On Wed, Nov 23, 2016 at 3:44 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 23/11/2016 02:14, David Matlack wrote:
>>       switch (msr_index) {
>>       case MSR_IA32_VMX_BASIC:
>> +             return vmx_restore_vmx_basic(vmx, data);
>> +     case MSR_IA32_VMX_TRUE_PINBASED_CTLS:
>> +     case MSR_IA32_VMX_PINBASED_CTLS:
>> +     case MSR_IA32_VMX_TRUE_PROCBASED_CTLS:
>> +     case MSR_IA32_VMX_PROCBASED_CTLS:
>> +     case MSR_IA32_VMX_TRUE_EXIT_CTLS:
>> +     case MSR_IA32_VMX_EXIT_CTLS:
>> +     case MSR_IA32_VMX_TRUE_ENTRY_CTLS:
>> +     case MSR_IA32_VMX_ENTRY_CTLS:
>
> PINBASED_CTLS, PROCBASED_CTLS, EXIT_CTLS and ENTRY_CTLS can be derived
> from their "true" counterparts, so I think it's better to remove the
> "non-true" ones from struct nested_vmx (and/or add the "true" ones when
> missing) and make them entirely computed.  But it can be done on top.

Good point. And that would mean userspace does not need to restore the
non-true MSRs, right? KVM does not emulate MSR_IA32_VMX_BASIC[55]=0,
and will probably never want to.