linux-kernel - Re: [PATCH] KVM: SVM: Mark SEV launch secret pages as dirty.

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Message-ID: <0ccf42d8-2803-c1db-73f0-884d1ea27282@redhat.com>
Date:   Wed, 23 Sep 2020 19:27:37 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Cfir Cohen <cfir@...gle.com>,
        "kvm @ vger . kernel . org" <kvm@...r.kernel.org>,
        Lendacky Thomas <thomas.lendacky@....com>,
        Singh Brijesh <brijesh.singh@....com>,
        Grimm Jon <Jon.Grimm@....com>,
        David Rientjes <rientjes@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: SVM: Mark SEV launch secret pages as dirty.

On 23/09/20 19:26, Sean Christopherson wrote:
> 	/*
> 	 * Flush before LAUNCH_UPDATE encrypts pages in place, in case the cache
> 	 * contains the data that was written unencrypted.
>  	 */
>  	sev_clflush_pages(inpages, npages);
> 
> there's nothing in the comment or code that even suggests sev_clflush_pages() is
> conditional, i.e. no reason for the reader to peek at the implemenation.
> 
> What about:
> 
> 	/*
> 	 * Flush (on non-coherent CPUs) before LAUNCH_UPDATE encrypts pages in
> 	 * place, the cache may contain data that was written unencrypted.
> 	 */

Sounds good.

Paolo