Re: [PATCH v6 07/14] x86: Secure Launch kernel early boot stub

[Ross Philipson]

On 5/15/23 21:45, Matthew Garrett wrote:
> On Mon, May 15, 2023 at 09:11:15PM -0400, Daniel P. Smith wrote:
> > On 5/12/23 12:17, Ross Philipson wrote:
> > > This is a good point. At this point it is really something we
> > > overlooked. We will have to revisit this and figure out the best way to
> > > find the final event log depending on how things booted.
> >
> > I believe Ross misunderstood what you were asking for here. There are two
> > reasons this is not possible or desired. The first reason is that on Intel,
> > the DRTM log is not initialized by TrenchBoot code in the preamble. It is
> > only responsible for allocating a buffer and recording the location in the
> > TXT structures. When the SINIT ACM is executed, it will initialize the log
> > and record the measurement that CPU sent directly to the TPM and then the
> > measurements the ACM makes of the environment. If you pointed at the SRTM
> > log, then the ACM would write over existing log, which I don't think you
> > want. Now if you pointed at the tail end of the SRTM log, you would still
> > end up with a second, separate log that just happens to be memory adjacent.
>
> Ok. I think it would be clearer if either the function names or some
> comments expressly indicated that this refers to the DRTM event log and
> that that's a separate entity from the SRTM one, "event log" on its own
> is likely to cause people to think of the existing log rather than
> associate it with something else.

That can be done, thanks.