Re: [PATCH] x86: only modify setup_data if the boot protocol indicates safety

[Gerd Hoffmann]

On Tue, Sep 06, 2022 at 12:27:25PM +0200, Jason A. Donenfeld wrote:
> Hi Gerd,
> 
> On Mon, Sep 5, 2022 at 10:40 AM Gerd Hoffmann <kraxel@redhat.com> wrote:
> >
> > On Sun, Sep 04, 2022 at 06:50:58PM +0200, Jason A. Donenfeld wrote:
> > > This reverts 3824e25db1 ("x86: disable rng seeding via setup_data"), and
> > > then makes the use of setup_data safe. It does so by checking the boot
> > > protocol version. If it's sufficient, then it means EFI boots won't
> > > crash. While we're at it, gate this on SEV too.
> >
> > > @@ -463,6 +462,7 @@ static void 
> > > pc_i440fx_7_0_machine_options(MachineClass *m)
> >
> > > +    pcmc->legacy_no_rng_seed = true;
> >
> > This needs go into the pc_i440fx_7_1_machine_options function, otherwise
> > legacy_no_rng_seed gets flipped from false to true for 7.1 machine types
> > which breaks compatibility.
> 
> Oh. Okay so a "straight" revert won't do the trick, since this is (I
> guess?) intended for 7.2 rather than 7.1. Makes sense; will do for v2.

Exactly.  7.1 is release and thus set in stone.  So we'll go flip the
switch for 7.2 because the feature missed the 7.1 boat.

take care,
  Gerd