Re: qemu-system-ppc64 option -smp 2 broken with commit 20b6643324a79860dcdfe811ffe4a79942bca21e

[Anushree Mathur]

On 6/23/23 19:16, Cédric Le Goater wrote:
> Hello Anushree,
>
> On 6/23/23 13:09, Anushree Mathur wrote:
> > Hi everyone,
> >
> > I was trying to boot rhel9.3 image with upstream qemu-system-ppc64 
> > -smp 2 option and observed a segfault (qemu crash).
> >
> > qemu command line used:
> >
> > qemu-system-ppc64 -name Rhel9.3.ppc64le -smp 2 -m 16G -vga none 
> > -nographic -machine pseries -cpu POWER10 -accel tcg -device 
> > virtio-scsi-pci -drive 
> > file=/home/rh93.qcow2,if=none,format=qcow2,id=hd0 -device 
> > scsi-hd,drive=hd0 -boot c
> >
> > After doing a git bisect, I found the first bad commit which 
> > introduced this issue is below:
>
> Could you please open a gitlab issue on QEMU project ?
>
>  https://gitlab.com/qemu-project/qemu/-/issues
>
> Thanks,
>
> C.
>
> > [qemu]# git bisect good
> > 20b6643324a79860dcdfe811ffe4a79942bca21e is the first bad commit
> > commit 20b6643324a79860dcdfe811ffe4a79942bca21e
> > Author: Richard Henderson <richard.henderson@linaro.org>
> > Date:   Mon Dec 5 17:45:02 2022 -0600
> >
> >      tcg/ppc: Reorg goto_tb implementation
> >
> >      The old ppc64 implementation replaces 2 or 4 insns, which leaves 
> > a race
> >      condition in which a thread could be stopped at a PC in the 
> > middle of
> >      the sequence, and when restarted does not see the complete address
> >      computation and branches to nowhere.
> >
> >      The new implemetation replaces only one insn, swapping between
> >
> >              b       <dest>
> >      and
> >              mtctr   r31
> >
> >      falling through to a general-case indirect branch.
> >
> >      Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> >      Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> >
> >   tcg/ppc/tcg-target.c.inc | 152 
> > +++++++++++++----------------------------------
> >   tcg/ppc/tcg-target.h     |   3 +-
> >   2 files changed, 41 insertions(+), 114 deletions(-)
> > [qemu]#
> >
> > Can someone please take a look and suggest a fix to resolve this issue?
> >
> > Thanks in advance.
> > Regards,
> > Anushree-Mathur
Hello Cedric,
> As per your mail, I have created the gitlab issue 
> https://gitlab.com/qemu-project/qemu/-/issues/1726.

Thanks & Regards,

Anushree-Mathur

>