Unicast H_SIGNAL_SYS_RESET does not find the target CPU if it is not the current CPU.
Signed-off-by: Nicholas Piggin <npig...@gmail.com> --- Unfortunately this slipped through without my noticing because the Linux driver for NMI IPIs has a fallback to using regular IPIs, and because Linux did not make much use of unicasts. A new watchdog has started using them. After this patch, this function works properly: Watchdog CPU:0 detected Hard LOCKUP other CPUS:3 *** Unicast NMI IPI is sent here *** Watchdog CPU:3 Hard LOCKUP Modules linked in: CPU: 3 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc3-00305-ge84cf82ae73a-dirty #1191 task: c00000001e440000 task.stack: c00000001e480000 NIP: c000000000023800 LR: c00000000000da28 CTR: c000000000626db0 REGS: c00000001ff97d80 TRAP: 0100 Not tainted (4.13.0-rc3-00305-ge84cf82ae73a-dirty) MSR: 8000000002001033 <SF,VEC,ME,IR,DR,RI,LE> CR: 48000224 XER: 20000000 CFAR: c00000000002380c SOFTE: 0 GPR00: c00000000000d9cc c00000001e483dc0 c000000000ebd900 000000000007d000 GPR04: f000000000078680 c00000001e1a0048 c00000001e1a0048 0000000000000001 GPR08: 0000000000000000 0000000000075036 00000003d5f633c2 0000000000000020 GPR12: 0000000000000000 c00000000fd80f00 c00000000000d988 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR24: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR28: 0000000000000000 0000000000000000 0000000000000000 0000000000000b60 NIP [c000000000023800] udelay+0x40/0x60 LR [c00000000000da28] kernel_init+0xa8/0x1b0 Call Trace: [c00000001e483dc0] [c00000000000d9cc] kernel_init+0x4c/0x1b0 (unreliable) [c00000001e483e30] [c00000000000bb1c] ret_from_kernel_thread+0x5c/0xc0 Instruction dump: 7c6349d2 7c210b78 7d4c42a6 7d2c42a6 7d2a4850 7fa34840 409d0028 48000014 60000000 60000000 60000000 60420000 <7d2c42a6> 7d2a4850 7fa34840 419dfff4 hw/ppc/spapr_hcall.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c index 72ea5a8247..f50e979b43 100644 --- a/hw/ppc/spapr_hcall.c +++ b/hw/ppc/spapr_hcall.c @@ -1432,7 +1432,9 @@ static target_ulong h_signal_sys_reset(PowerPCCPU *cpu, } else { /* Unicast */ CPU_FOREACH(cs) { - if (cpu->cpu_dt_id == target) { + PowerPCCPU *c = POWERPC_CPU(cs); + + if (c->cpu_dt_id == target) { run_on_cpu(cs, spapr_do_system_reset_on_cpu, RUN_ON_CPU_NULL); return H_SUCCESS; } -- 2.13.3