[PATCH 2/2] tpm: get tpm event log from bloblist

[Raymond Mao]

Hi Simon,

On Mon, 16 Dec 2024 at 10:20, Simon Glass <sjg at chromium.org> wrote:

> Hi Raymond,
>
> On Mon, 16 Dec 2024 at 07:52, Raymond Mao <raymond.mao at linaro.org> wrote:
> >
> > Hi Simon,
> >
> > On Sun, 15 Dec 2024 at 19:25, Simon Glass <sjg at chromium.org> wrote:
> >>
> >> Hi Raymond,
> >>
> >> On Fri, 13 Dec 2024 at 15:56, Raymond Mao <raymond.mao at linaro.org>
> wrote:
> >> >
> >> > Get tpm event log from bloblist instead of FDT when bloblist is
> >> > enabled and valid from previous boot stage.
> >> >
> >> > Note:
> >> > This patch depends on:
> >> > [PATCH 1/2] bloblist: Introduce BLOBLIST_PRIOR_STAGE options
> >> >
> https://lore.kernel.org/u-boot/20241212151142.1562825-1-trini@konsulko.com/
> >> >
> >> > Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
> >> > ---
> >> >  lib/tpm_tcg2.c | 7 +++++++
> >> >  1 file changed, 7 insertions(+)
> >> >
> >> > diff --git a/lib/tpm_tcg2.c b/lib/tpm_tcg2.c
> >> > index 7f868cc883..acaf0acb88 100644
> >> > --- a/lib/tpm_tcg2.c
> >> > +++ b/lib/tpm_tcg2.c
> >> > @@ -19,6 +19,7 @@
> >> >  #include <linux/unaligned/generic.h>
> >> >  #include <linux/unaligned/le_byteshift.h>
> >> >  #include "tpm-utils.h"
> >> > +#include <bloblist.h>
> >> >
> >> >  int tcg2_get_pcr_info(struct udevice *dev, u32 *supported_pcr, u32
> *active_pcr,
> >> >                       u32 *pcr_banks)
> >> > @@ -672,6 +673,12 @@ __weak int tcg2_platform_get_log(struct udevice
> *dev, void **addr, u32 *size)
> >> >         *addr = NULL;
> >> >         *size = 0;
> >> >
> >> > +       if (CONFIG_IS_ENABLED(BLOBLIST_PRIOR_STAGE) &&
> !bloblist_maybe_init()) {
> >>
> >> Please drop the second term...the bloblist is inited by U-Boot already.
> >>
> >
> > As an independent library, from the tpm library's angle, whether the
> bloblist init was already called or not is agnostic.
> > I think this is the purpose of the "maybe" function.
>
> No. U-Boot does init at the start. We don't want each subsystem
> 'maybe' initing each other subsystem that it uses. If you want to
> check whether bloblist is available, you can use the GD flag.
>
>
OK. I can use the gd instead.


> >
> >>
> >> Also please drop the first term. If you find it in the bloblist, just
> use it.
> >>
> >
> > I think here we should have the same logic as the existing one in fdtdec:
> > If bloblist is not enabled or errors observed, do a fallback to the
> original process.
> > At least I want to keep the same logic in different places before
> everything is ready from TF-A to U-boot.
>
> Yes, your second line is right. But PRIOR_STAGE doesn't exist, nor
> should it. Nor do you need it, since you can just check the bloblist
> for what you want. If you don't find it, fall back.
>
>
Since Firmware Handoff is still an experimental feature and not mandatory
yet (at least now),
I put everything under PRIOR_STAGE to allow users to disable it by their
own decisions.
I saw PRIOR_STAGE in one of Tom's recent patches so I have added a
dependency claim in my commit message.


> >
> > [snip]
>
> REgards,
> Simon
>