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

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Aug 09, 2017 at 03:59:36AM +1000, Nicholas Piggin wrote:
> 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:

In fact this bug was already fixed in the for-2.11 branch.  If you've
hit this for real, I guess it's more important than I realized, so
I'll pull it into 2.10 instead.

> 
> 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;
>              }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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