[Qemu-devel] [PATCH] ppc/spapr: fix unicast H_SIGNAL_SYS_RESET

[Nicholas Piggin <npiggin@gmail.com>]

Unicast H_SIGNAL_SYS_RESET does not find the target CPU if it
is not the current CPU.

Signed-off-by: Nicholas Piggin <npiggin@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