Message ID | 20180329144911.18829-1-clg@kaod.org (mailing list archive) |
---|---|
State | Superseded |
Headers | show |
Series | [RFC] powerpc/64/kexec: fix race in kexec when XIVE is shutdown | expand |
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(); }
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. Signed-off-by: Cédric Le Goater <clg@kaod.org> --- If this is a bad idea, there are alternate solutions : - introduce a new kexec_state and barrier - test for such error in all possible XIVE hcalls. But I tend to prefer the proposed one. Thanks, C. arch/powerpc/kernel/machine_kexec_64.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)