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

[Michael S. Tsirkin]

On Thu, Aug 04, 2022 at 12:08:07AM +0200, Jason A. Donenfeld wrote:
> 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.

Sure but it's still a regression.

> 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

Maybe.

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MST