linux-kernel - Re: [PATCH v3 3/4] KVM: nVMX: Track whether changes in L0 require MSR bitmap for L2 to be rebuilt

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Message-ID: <875yt6lscj.fsf@vitty.brq.redhat.com>
Date:   Fri, 05 Nov 2021 13:06:20 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] KVM: nVMX: Track whether changes in L0 require
 MSR bitmap for L2 to be rebuilt

Sean Christopherson <seanjc@...gle.com> writes:

> On Wed, Oct 13, 2021, Vitaly Kuznetsov wrote:
>> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
>> index 592217fd7d92..2cdf66e6d1b0 100644
>> --- a/arch/x86/kvm/vmx/vmx.h
>> +++ b/arch/x86/kvm/vmx/vmx.h
>> @@ -148,6 +148,15 @@ struct nested_vmx {
>>  	bool need_vmcs12_to_shadow_sync;
>>  	bool dirty_vmcs12;
>>  
>> +	/*
>> +	 * Indicates whether MSR bitmap for L2 needs to be rebuilt due to
>> +	 * changes in MSR bitmap for L1 or switching to a different L2. Note,
>> +	 * this flag can only be used reliably in conjunction with a paravirt L1
>> +	 * which informs L0 whether any changes to MSR bitmap for L2 were done
>> +	 * on its side.
>> +	 */
>> +	bool msr_bitmap_force_recalc;
>
> Belated bikeshedding...  What about need_msr_bitmap_recalc to follow the above
> need_vmcs12_to_shadow_sync?
>

'msr_bitmap_force_recalc' was suggested by Paolo but
'need_msr_bitmap_recalc' sounds equally good to me.

>> +
>>  	/*
>>  	 * Indicates lazily loaded guest state has not yet been decached from
>>  	 * vmcs02.
>> -- 
>> 2.31.1
>> 
>

-- 
Vitaly