Message-ID: <6c9f774e908fe6e50626a1806ea89dccb7f988c5.camel@linux.ibm.com>
Subject: Re: [PATCH v4 22/24] powerpc/pseries: Implement secvars for dynamic
 secure boot
From:   Andrew Donnellan <ajd@linux.ibm.com>
To:     Nicholas Piggin <npiggin@gmail.com>, linuxppc-dev@lists.ozlabs.org,
        linux-integrity@vger.kernel.org
Cc:     sudhakar@linux.ibm.com, bgray@linux.ibm.com, erichte@linux.ibm.com,
        gregkh@linuxfoundation.org, nayna@linux.ibm.com,
        linux-kernel@vger.kernel.org, zohar@linux.ibm.com,
        gjoyce@linux.ibm.com, ruscur@russell.cc, gcwilson@linux.ibm.com,
        joel@jms.id.au
Date:   Tue, 31 Jan 2023 15:25:44 +1100
In-Reply-To: <9f16d86e855f22823ee24e6a6236a16556425f29.camel@linux.ibm.com>
References: <20230120074306.1326298-1-ajd@linux.ibm.com>
         <20230120074306.1326298-23-ajd@linux.ibm.com>
         <CQ05ZDYG6KNU.1G9O3ITQDIHEM@bobo>
         <9f16d86e855f22823ee24e6a6236a16556425f29.camel@linux.ibm.com>
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On Tue, 2023-01-31 at 13:54 +1100, Andrew Donnellan wrote:
> > > +{
> > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0// The max object size rep=
orted by the hypervisor is
> > > accurate for the
> > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0// object itself, but we u=
se the first 8 bytes of data on
> > > write as the
> > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0// signed update flags, so=
 the max size a user can write
> > > is
> > > larger.
> > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0*max_size =3D (u64)plpks_g=
et_maxobjectsize() + 8;
> >=20
> > You have this 8 open coded twice (once as sizeof(u64)). You could
> > make
> > it a #define at the top with a brief overview of the hcall format
> > so
> > you
> > don't need so much commentage for it. Although a note here that the
> > objsize does not include the flags bytes is good to keep.
>=20
> Will do.

Thinking about this further, I'm going to change the 8 to sizeof(u64)
to make it clearer that it's linked with the type of the flags
variable, but I am going to keep the other cases as is (they're
sizeof(flags), not sizeof(u64), so it's already obvious how they work,
and I don't want to define a macro for one user).


--=20
Andrew Donnellan    OzLabs, ADL Canberra
ajd@linux.ibm.com   IBM Australia Limited