linux-kernel - Re: [PATCH v2 6/6] KVM: nVMX: optimize prepare_vmcs02{,

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Date:   Tue, 24 Jul 2018 19:09:04 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Roman Kagan <rkagan@...tuozzo.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>,
        Mohammed Gamal <mmorsy@...hat.com>,
        Cathy Avery <cavery@...hat.com>, linux-kernel@...r.kernel.org,
        Jim Mattson <jmattson@...gle.com>,
        Liran Alon <liran.alon@...cle.com>
Subject: Re: [PATCH v2 6/6] KVM: nVMX: optimize prepare_vmcs02{,_full} for
 Enlightened VMCS case

On 21/06/2018 14:30, Vitaly Kuznetsov wrote:
> +static __always_inline bool evmcs_needs_write(struct vcpu_vmx *vmx,
> +					      u16 clean_field)
> +{
> +	if (vmx->nested.dirty_vmcs12)
> +		return true;

Why is this needed?  If it weren't for it, you could pass hv_evmcs
directly to evmcs_needs_write, which would simplify the code a bit in
the caller.

Paolo

> +	return !(vmx->nested.hv_evmcs->hv_clean_fields & clean_field);