linux-kernel - Re: [RFC 03/16] KVM: selftests: handle encryption bits in page tables

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Message-ID: <20211025141427.u2dstri5ehgegryk@amd.com>
Date:   Mon, 25 Oct 2021 09:14:27 -0500
From:   Michael Roth <michael.roth@....com>
To:     Paolo Bonzini <pbonzini@...hat.com>
CC:     <linux-kselftest@...r.kernel.org>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <x86@...nel.org>,
        Nathan Tempelman <natet@...gle.com>,
        Marc Orr <marcorr@...gle.com>,
        Steve Rutherford <srutherford@...gle.com>,
        Sean Christopherson <seanjc@...gle.com>,
        "Mingwei Zhang" <mizhang@...gle.com>,
        Brijesh Singh <brijesh.singh@....com>,
        "Tom Lendacky" <thomas.lendacky@....com>,
        Varad Gautam <varad.gautam@...e.com>,
        Shuah Khan <shuah@...nel.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        "David Woodhouse" <dwmw@...zon.co.uk>,
        Ricardo Koller <ricarkol@...gle.com>,
        "Jim Mattson" <jmattson@...gle.com>,
        Wanpeng Li <wanpengli@...cent.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>
Subject: Re: [RFC 03/16] KVM: selftests: handle encryption bits in page tables

On Mon, Oct 25, 2021 at 09:34:10AM +0200, Paolo Bonzini wrote:
> On 24/10/21 18:49, Michael Roth wrote:
> > So test code would need to consider cases where addr_gpa2raw() needs to be
> > used to set the C-bit (which is basically only when they want to mix usage
> > of the vm_phy_page[s]_alloc with their own mapping of the guest page tables,
> > which doesn't seem to be done in any existing tests anyway).
> 
> Yes, and it seems like a more rare case in general.
> 
> > The library code would need these addr_gpa2raw() hooks in places where
> > it calls virt_*map() internally. Probably just a handful of places
> > though.
> 
> Either that, or you can have virt_*map that consults the encryption bitmap,
> and virt_*map_enc (or _raw, doesn't matter) that takes the encryption state
> explicitly as a bool.

That sounds promising. Will give that a shot. Thanks!