Re: [PULL 00/10] ppc queue

[Nicholas Piggin]

On Mon May 29, 2023 at 3:36 AM AEST, Michael Tokarev wrote:
> 28.05.2023 19:49, Daniel Henrique Barboza wrote:
> > 
> >    https://gitlab.com/danielhb/qemu.git tags/pull-ppc-20230528
> > 
> > ppc patch queue for 2023-05-28:
> > 
> > This queue includes several assorted fixes for PowerPC SPR
> > emulation, a change in the default Pegasos2 CPU, the addition
> > of AIL mode 3 for spapr, a PIC->CPU interrupt fix for prep and
> > performance enhancements in fpu_helper.c.
>
>  From the patch description, it looks like the following changes
> are suitable for -stable:
>
> 01/10 target/ppc: Fix fallback to MFSS for MFFS* instructions on pre 3.0 ISAs
> 02/10 target/ppc: Fix width of some 32-bit SPRs
> 03/10 target/ppc: Alignment faults do not set DSISR in ISA v3.0 onward
> 05/10 hw/ppc/prep: Fix wiring of PIC -> CPU interrupt
>
> Or are these not important for -stable?  Or maybe there are other changes
> which should be picked too?

They certainly fix some parts of target emulation, but what is the
guidance for backporting those type of fixes? Most of the patches I sent
including 2,3 were just found from inspection or new test code and not
real software failing.

Should just simple ones go in? 32-bit SPRs do not fix entirely the
behaviour of all SPRs, just one aspect. In another fix I had (that
didn't make it in this merge), was a bit more complicated and the
first iteration caused a deadlock that didn't show up in basic test
like booting Linux.

My guess is that fixes that correct an issue with real software running
on the target should be ported to stable. Perhaps "obviously correct"
small fixes as well. But not sure about larger changes.

Thanks,
Nick