linux-kernel - Re: [PATCH 15/54] KVM: nSVM: Add a comment to document why nNPT uses vmcb01, not vCPU state

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Message-ID: <YNOeRCntGwh5QVz2@google.com>
Date:   Wed, 23 Jun 2021 20:49:08 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: Re: [PATCH 15/54] KVM: nSVM: Add a comment to document why nNPT uses
 vmcb01, not vCPU state

On Wed, Jun 23, 2021, Paolo Bonzini wrote:
> On 22/06/21 19:57, Sean Christopherson wrote:
> > +	/*
> > +	 * L1's CR4 and EFER are stuffed into vmcb01 by the caller.  Note, when
> > +	 * called via KVM_SET_NESTED_STATE, that state may_not_  match current
> > +	 * vCPU state.  CR0.WP is explicitly ignored, while CR0.PG is required.
> > +	 */
> 
> "stuffed into" doesn't really match reality of vmentry, though it works for
> KVM_SET_NESTED_STATE.  What about a more neutral "The NPT format depends on
> L1's CR4 and EFER, which is in vmcb01"?

Ah, true.  Works for me.