Re: [PATCH v2 4/4] ibmvtpm: Add support for trusted boot using a vTPM 2.0

[Daniel Kiper]

On Thu, Jul 29, 2021 at 09:30:49AM -0400, Stefan Berger wrote:
> On 7/28/21 9:25 AM, Daniel Kiper wrote:
> > On Tue, Jul 20, 2021 at 05:14:49PM -0400, Stefan Berger wrote:
> >
> > > +#define IEEE1275_CELL_TRUE     ((grub_ieee1275_cell_t) -1)
> > This smells like global constant. Does not it? If yes could you define it
> > in a global header and use it? Maybe even replace existing comparisons
> > in the IEEE1275 code with IEEE1275_CELL_TRUE. But probably then
> > s/IEEE1275_CELL_TRUE/GRUB_IEEE1275_CELL_TRUE/...
>
> I wasn't sure and also had found local #defines in another .c file.
>
> #define IEEE1275_PHANDLE_INVALID  ((grub_ieee1275_cell_t) -1)
> #define IEEE1275_IHANDLE_INVALID  ((grub_ieee1275_cell_t) 0)
> #define IEEE1275_CELL_INVALID     ((grub_ieee1275_cell_t) -1)
>
> https://git.savannah.gnu.org/cgit/grub.git/tree/grub-core/kern/ieee1275/ieee1275.c#n24
>
> I haven't seen the usage of -1 as TRUE in other grub files. So I could move
> it to a global header file assuming this is commonly used on this platform.
> I have only seen usage of -1 as TRUE in the SLOF firmware in this file here:
>
> https://github.com/aik/SLOF/blob/master/lib/libnvram/libnvram.code#L66
>
> but then of course also here:
> https://github.com/aik/SLOF/blob/master/lib/libtpm/tcgbios.c#L965

I think we should use IEEE1275_CELL_INVALID in your code. IMO the TRUE
sounds a bit confusing in this context. So, I would move all these
three constants to a global IEEE1275 header and add "GRUB_" prefix.

Daniel