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: <b759e31b-6269-a401-9fbb-49227b8be009@redhat.com>
Date:   Wed, 23 Jun 2021 19:06:54 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.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 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"?

Paolo