Cédric Le Goater <c...@kaod.org> writes: > The kexec_state KEXEC_STATE_IRQS_OFF barrier is reached by all > secondary CPUs before the kexec_cpu_down() operation is called on > secondaries. This can raise conflicts and provoque errors in the XIVE > hcalls when XIVE is shutdowned with H_INT_RESET on the primary CPU. > > To synchronize the kexec_cpu_down() operations and make sure the > secondaries have completed their task before the primary starts doing > the same, let's move the primary kexec_cpu_down() after the > KEXEC_STATE_REAL_MODE barrier.
This sounds reasonable, I'm sure you've tested it. I'm just a bit worried that it could potentially break on other platforms because it changes the sequence of operations. Looking we only have kexec_cpu_down() implemented for pseries, powernv, ps3 and 85xx. We can easily test the first two. ps3 doesn't do much so hopefully that's safe. mpc85xx_smp_kexec_cpu_down() does very little on 32-bit, and on 64-bit it seems to already wait for at least one other CPU to get into KEXEC_STATE_REAL_MODE, so that's probably safe too. So I guess I'm OK to merge this, and we'll fix any fallout. It would be good for the change log to call out the change though, and that we think it's a sensible change for all platforms. cheers > Signed-off-by: Cédric Le Goater <c...@kaod.org> > --- > arch/powerpc/kernel/machine_kexec_64.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/kernel/machine_kexec_64.c > b/arch/powerpc/kernel/machine_kexec_64.c > index 49d34d7271e7..212ecb8e829c 100644 > --- a/arch/powerpc/kernel/machine_kexec_64.c > +++ b/arch/powerpc/kernel/machine_kexec_64.c > @@ -230,16 +230,16 @@ static void kexec_prepare_cpus(void) > /* we are sure every CPU has IRQs off at this point */ > kexec_all_irq_disabled = 1; > > - /* after we tell the others to go down */ > - if (ppc_md.kexec_cpu_down) > - ppc_md.kexec_cpu_down(0, 0); > - > /* > * Before removing MMU mappings make sure all CPUs have entered real > * mode: > */ > kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE); > > + /* after we tell the others to go down */ > + if (ppc_md.kexec_cpu_down) > + ppc_md.kexec_cpu_down(0, 0); > + > put_cpu(); > } > > -- > 2.13.6
