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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Date:   Fri, 5 Nov 2021 01:05:50 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.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

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?

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