Re: [PATCH v11 00/20] x86: Trenchboot secure dynamic launch Linux kernel support

["Jarkko Sakkinen" <jarkko@kernel.org>]

On Fri Nov 1, 2024 at 10:50 AM EET, Ard Biesheuvel wrote:
> On Fri, 1 Nov 2024 at 01:40, Jarkko Sakkinen <jarkko@kernel.org> wrote:
> >
> > On Fri Nov 1, 2024 at 2:33 AM EET, Jarkko Sakkinen wrote:
> > > On Fri Nov 1, 2024 at 1:08 AM EET, Thomas Gleixner wrote:
> > > > On Fri, Nov 01 2024 at 00:37, Jarkko Sakkinen wrote:
> > > > > On Thu Oct 31, 2024 at 9:25 PM EET, Thomas Gleixner wrote:
> > > > >> So this looks pretty reasonable to me by now and I'm inclined to take it
> > > > >> through the tip x86 tree, but that needs reviewed/acked-by's from the
> > > > >> crypto and TPM folks. EFI has been reviewed already.
> > > > >>
> > > > >> Can we make progress on this please?
> > > > >
> > > > > So TPM patches do have bunch of glitches:
> > > > >
> > > > > - 15/20: I don't get this. There is nothing to report unless tree
> > > > >   is falling. The reported-by tag literally meaningless. Maybe this
> > > > >   is something that makes sense with this feature. Explain from that
> > > > >   angle.
> > > > > - 16/20: Is this actually a bug fix? If it is should be before 15/20.
> > > > > - 17/20: the commit message could do a better job explaining how the
> > > > >   locality can vary. I'm not sure how this will be used by rest of
> > > > >   the patch set.
> > > > > - 18/20: I'm not confident we want to give privilege to set locality
> > > > >   to the user space. The commit message neither makes a case of this.
> > > > >   Has this been tested to together with bus encryption (just checking)?
> > > >
> > > > Can you please explicitely voice your detailed technical concerns in
> > > > replies to the actual patches?
> > >
> > > - 15/20 looks like a rigged patch. I don't really know why it is done
> > >   so it is hard to either suggest how "resolve it".
> > > - 16/20 probably makes sense but if it is a bug fix or part of it is,
> > >   the bug fix should have relevant fixes etc tags so that it can be
> > >   picked up to stable kernels.
> > > - 17-18/20: I'd speak about this as the "one whole" i.e. here the
> > >   privilege to be able change locality during run-time is really
> > >   concerning. Could the locality be figured out for the kernel
> > >   command-line instead? The sysfs attribute can exist as read-only.
> > >
> > > So yeah, the way I see it 15-16 are the more trivial issue to sort
> > > out (probably) but with 17-18 we have an actual architectural concern
> > > for kernel overall.
> >
> > Further:
> >
> > 15/20: I can accept this without reported-by tag (or changed as
> > suggested-by). It does not harm.
> > 16/20: I'll re-review this with time. I'll try to get this done
> > latest next week.
> >
> > So let's put focus only on 17 and 18. Can this problem be sorted out
> > by kernel command-line parameter? In the case of locality we want to
> > keep regular "chain of trust" i.e. boot-loader makes the decision,
> > *even* in the case of DRTM. I would call this almost as constraint
> > that would be wise to set.
> >
>
> Please don't add a kernel command line parameter for this - the code
> running in the decompressor will be the one setting it and there are
> better ways to pass information between these components (and the
> slaunch stack is already doing that in any case)

Not sure if I follow this (I don't know what "decompressor" is).

> Also, let's have this discussion in the appropriate place, i.e., on
> the thread for each respective patch.

Sure, I just did not have a lot of time to download the patch.

BR, Jarkko