Re: [PULL 9/9] hw/i386: pass RNG seed via setup_data entry

[Jason A. Donenfeld]

Hi Michael,

On Wed, Aug 03, 2022 at 06:03:20PM -0400, Michael S. Tsirkin wrote:
> On Wed, Aug 03, 2022 at 07:07:52PM +0200, Jason A. Donenfeld wrote:
> > On Wed, Aug 03, 2022 at 03:34:04PM +0200, Jason A. Donenfeld wrote:
> > > On Wed, Aug 03, 2022 at 03:11:48PM +0200, Jason A. Donenfeld wrote:
> > > > Thanks for the info. Very helpful. Looking into it now.
> > > 
> > > So interestingly, this is not a new issue. If you pass any type of setup
> > > data, OVMF appears to be doing something unusual and passing 0xffffffff
> > > for all the entries, rather than the actual data. The reason this isn't
> > > new is: try passing `-dtb any/dtb/at/all/from/anywhere` and you get the
> > > same page fault, on all QEMU versions. The thing that passes the DTB is
> > > the thing that passes the RNG seed. Same mechanism, same bug.
> > > 
> > > I'm looking into it...
> > 
> > Fixed with: 
> > 20220803170235.1312978-1-Jason@zx2c4.com/">https://lore.kernel.org/all/20220803170235.1312978-1-Jason@zx2c4.com/
> > 
> > Feel free to join into the discussion there. I CC'd you.
> > 
> > Jason
> 
> Hmm I don't think this patch will make it in 7.1 given the
> timeframe. I suspect we should revert the patch for now.
> 
> Which is where you maybe begin to see why we generally
> prefer doing it with features - one can then work around
> bugs by turning the feature on and off.

The bug actually precedes this patch. Just boot with -dtb on any qemu
version and you'll trigger it. We're still at rc0; there should be time
enough for a bug fix. Please do chime in on that thread and maybe we can
come up with something reasonable fast enough.

Jason