[PATCH v5 3/3] tpm: get tpm event log from bloblist

[Simon Glass]

Hi Ilias,

On Thu, 16 Jan 2025 at 07:35, Ilias Apalodimas <ilias.apalodimas at linaro.org>
wrote:
>
> On Wed, 15 Jan 2025 at 03:17, Simon Glass <sjg at chromium.org> wrote:
> >
> > Hi Raymond,
> >
> > On Tue, 14 Jan 2025 at 08:20, 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.
> > >
> > > As a fallback, when no event log from previous stage is observed
> > > and no user buffer is passed, malloc a default buffer to initialize
> > > the event log.
> > >
> > > Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
> > > ---
> > > Changes in v2
> > > - Remove patch dependency.
> > > - Remove the fallback to FDT when BLOBLIST is selected.
> > > Changes in v3
> > > - Malloc an 8KB buffer when user eventlog buffer does not exist.
> > > Changes in v4
> > > - Replace the default eventlog size with TPM2_EVENT_LOG_SIZE.
> > > Changes in v5
> > > - Replace TPM2_EVENT_LOG_SIZE with CONFIG_TPM2_EVENT_LOG_SIZE.
> > > - Add an inline TODO comment.
> > >
> > >  lib/tpm_tcg2.c | 61
++++++++++++++++++++++++++++++++++----------------
> > >  1 file changed, 42 insertions(+), 19 deletions(-)
> >
> > Reviewed-by: Simon Glass <sjg at chromium.org>
> >
> > nit in case you respin again: -ENODEV is for driver model, when there
> > is no device. It is actually handling specially by driver model. So
> > -ENOENT is what I try to use for things that don't exist but aren't
> > devices.
> >
>
> +1,
>
>
> > >
> > > diff --git a/lib/tpm_tcg2.c b/lib/tpm_tcg2.c
> > > index 4134d93a35..2d9076f091 100644
> > > --- a/lib/tpm_tcg2.c
> > > +++ b/lib/tpm_tcg2.c
> > > @@ -5,6 +5,7 @@
> > >
> > >  #include <dm.h>
> > >  #include <dm/of_access.h>
> > > +#include <malloc.h>
> > >  #include <tpm_api.h>
> > >  #include <tpm-common.h>
> > >  #include <tpm-v2.h>
> > > @@ -19,6 +20,7 @@
> > >  #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_bank, u32
*active_bank,
> > >                       u32 *bank_num)
> > > @@ -615,15 +617,24 @@ int tcg2_log_prepare_buffer(struct udevice
*dev, struct tcg2_event_log *elog,
> > >                 elog->found = log.found;
> > >         }
> > >
> > > +       if (elog->found)
> > > +               return 0;
> > > +
> > >         /*
> > > -        * Initialize the log buffer if no log was discovered and the
buffer is
> > > -        * valid. User's can pass in their own buffer as a fallback
if no
> > > -        * memory region is found.
> > > +        * Initialize the log buffer if no log was discovered.
> > > +        * User can pass in their own buffer as a fallback if no
memory region
> > > +        * is found, else malloc a buffer if it does not exist.
> > >          */
> > > -       if (!elog->found && elog->log_size)
> > > -               rc = tcg2_log_init(dev, elog);
> > > +       if (!elog->log_size) {
> > > +               elog->log = malloc(CONFIG_TPM2_EVENT_LOG_SIZE);
> > > +               if (!elog->log)
> > > +                       return -ENOMEM;
> > > +
> > > +               memset(elog->log, 0, CONFIG_TPM2_EVENT_LOG_SIZE);
> > > +               elog->log_size = CONFIG_TPM2_EVENT_LOG_SIZE;
>
> Why are you doing this? There are 2 ways to pass an EventLog to the
> kernel. Either via a config table from EFI, or using sml-base and
> sml-size in a DT (which are both required). IOW you will create an
> EventLog no one will discover

My understanding is that it is still added to those tables (e.g. EFI).
Linux does not see the bloblist structure.

Regards,
Simon