linux-kernel - Re: [PATCH v4 22/24] powerpc/pseries: Implement secvars for dynamic secure boot

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Date:   Tue, 31 Jan 2023 15:25:44 +1100
From:   Andrew Donnellan <ajd@...ux.ibm.com>
To:     Nicholas Piggin <npiggin@...il.com>, linuxppc-dev@...ts.ozlabs.org,
        linux-integrity@...r.kernel.org
Cc:     sudhakar@...ux.ibm.com, bgray@...ux.ibm.com, erichte@...ux.ibm.com,
        gregkh@...uxfoundation.org, nayna@...ux.ibm.com,
        linux-kernel@...r.kernel.org, zohar@...ux.ibm.com,
        gjoyce@...ux.ibm.com, ruscur@...sell.cc, gcwilson@...ux.ibm.com,
        joel@....id.au
Subject: Re: [PATCH v4 22/24] powerpc/pseries: Implement secvars for dynamic
 secure boot

On Tue, 2023-01-31 at 13:54 +1100, Andrew Donnellan wrote:
> > > +{
> > > +       // The max object size reported by the hypervisor is
> > > accurate for the
> > > +       // object itself, but we use the first 8 bytes of data on
> > > write as the
> > > +       // signed update flags, so the max size a user can write
> > > is
> > > larger.
> > > +       *max_size = (u64)plpks_get_maxobjectsize() + 8;
> > 
> > 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.
> 
> 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).


-- 
Andrew Donnellan    OzLabs, ADL Canberra
ajd@...ux.ibm.com   IBM Australia Limited