linux-kernel - Re: [PATCH 3/6] libstub,tpm: provide indication of failure when getting event log

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Message-ID: <CAC_iWjKFmHUV4EzhfJ_OAHOZhrAzH35O8QMzVK_Zs2aTG5h+1Q@mail.gmail.com>
Date: Fri, 13 Sep 2024 16:10:08 +0300
From: Ilias Apalodimas <ilias.apalodimas@...aro.org>
To: Gregory Price <gourry@...rry.net>
Cc: linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org, ardb@...nel.org, 
	leitao@...ian.org, usamaarif642@...il.com, 
	sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH 3/6] libstub,tpm: provide indication of failure when
 getting event log

On Fri, 13 Sept 2024 at 15:58, Gregory Price <gourry@...rry.net> wrote:
>
> On Fri, Sep 13, 2024 at 09:59:03AM +0300, Ilias Apalodimas wrote:
> > Hi Gregory,
> >
> > On Fri, 6 Sept 2024 at 23:28, Gregory Price <gourry@...rry.net> wrote:
> > >
> > > If get_event_log fails, at least provide an indicator of this failure
> > > to assist debugging later failures that attempt to interact with it.
> > >
> > > Signed-off-by: Gregory Price <gourry@...rry.net>
> > > ---
> > >  drivers/firmware/efi/libstub/tpm.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/firmware/efi/libstub/tpm.c b/drivers/firmware/efi/libstub/tpm.c
> > > index df3182f2e63a..192914e04e0f 100644
> > > --- a/drivers/firmware/efi/libstub/tpm.c
> > > +++ b/drivers/firmware/efi/libstub/tpm.c
> > > @@ -185,8 +185,10 @@ void efi_retrieve_eventlog(void)
> > >                         get_efi_config_table(EFI_CC_FINAL_EVENTS_TABLE_GUID);
> > >         }
> > >
> > > -       if (status != EFI_SUCCESS || !log_location)
> > > +       if (status != EFI_SUCCESS || !log_location) {
> > > +               efi_err("TPM unable to provide Event Log\n");
> >
> > s/provide/retrieve/ and yes the print is going to be useful.  Do you
> > know if the EventLog is mandatory. Reading at the spec GetEventlog
> > only has 2 return values, which implies you can't return "Not
> > supported", but it's not explicitly stated anywhere
> >
>
> I believe it is mandatory from my reading of the spec - but the
> "Final Event Log" was only added in 2.0.  We report an error when
> 2.0 is reported but the final event log is not supported, so i figure
> we should probably report when the event log fails as well.

Yea I am fine with that, I was just wondering if we should do _err or
_warn. I am fine with the error

/Ilias
>
> > Thanks
> > /Ilias
> > >                 return;
> > > +       }
> > >
> > >         efi_retrieve_tcg2_eventlog(version, log_location, log_last_entry,
> > >                                    truncated, final_events_table);
> > > --
> > > 2.43.0
> > >