linux-kernel - Re: [PATCH v2 1/4] powerpc/powernv: Add OPAL API interface to access secure variable

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Message-ID: <CAOSf1CHOsnnC94DxHhG4opZfYjV7u_ndrE2B3Cr6ZV58RAxoWA@mail.gmail.com>
Date:   Thu, 22 Aug 2019 15:41:17 +1000
From:   "Oliver O'Halloran" <oohall@...il.com>
To:     Nayna Jain <nayna@...ux.ibm.com>,
        linuxppc-dev <linuxppc-dev@...abs.org>,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Jeremy Kerr <jk@...abs.org>,
        Matthew Garret <matthew.garret@...ula.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Claudio Carvalho <cclaudio@...ux.ibm.com>,
        George Wilson <gcwilson@...ux.ibm.com>,
        Elaine Palmer <erpalmer@...ibm.com>,
        Eric Ricther <erichte@...ux.ibm.com>
Subject: Re: [PATCH v2 1/4] powerpc/powernv: Add OPAL API interface to access
 secure variable

On Thu, Aug 22, 2019 at 3:02 PM Oliver O'Halloran <oohall@...il.com> wrote:
>
> On Wed, 2019-08-21 at 11:08 -0400, Nayna Jain wrote:
> > diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> > index aba443be7daa..ffe6f1cf0830 100644
> > --- a/arch/powerpc/platforms/powernv/opal.c
> > +++ b/arch/powerpc/platforms/powernv/opal.c
> > @@ -32,6 +32,8 @@
> >  #include <asm/mce.h>
> >  #include <asm/imc-pmu.h>
> >  #include <asm/bug.h>
> > +#include <asm/secvar.h>
> > +#include <asm/secboot.h>
> >
> >  #include "powernv.h"
> >
> > @@ -988,6 +990,9 @@ static int __init opal_init(void)
> >       /* Initialise OPAL Power control interface */
> >       opal_power_control_init();
> >
> > +     if (is_powerpc_secvar_supported())
> > +             secvar_init();
> > +
>
> The usual pattern here is to have the init function check for support
> internally.
>
> Also, is_powerpc_secvar_supported() doesn't appear to be defined
> anywhere. Is that supposed to be is_opal_secvar_supported()? Or is this
> series supposed to be applied on top of another series?

To answer my own question, yes it depends on the series at [1] which
adds IMA support. Turns out actually reading the cover letter helps,
who knew.

That said, I'm still not entirely sure about this. The implementation
of is_powerpc_secvar_supported() in [2] parses the DT and seems to
assume the DT bindings that OPAL produces. Are those common with the
DT bindings produced by OF when running on pseries?

[1] http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=125961
[2] http://patchwork.ozlabs.org/patch/1149257/

>
> >       return 0;
> >  }
> >  machine_subsys_initcall(powernv, opal_init);
>