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

[David Gibson]

On Wed, Aug 09, 2017 at 03:07:19PM +1000, Nicholas Piggin wrote:
> On Wed, 9 Aug 2017 14:05:46 +1000
> David Gibson <address@hidden> wrote:
> 
> > 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 <address@hidden>
> > > ---
> > > 
> > > 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.
> 
> Oh sorry I didn't notice the 2.11 branch fix. Yes please pull it
> into 2.10 if possible.

Already pulled into my ppc-for-2.10 tree, I'm preparing a pull request
at this moment.

> 
> Thanks,
> Nick
> 
> > 
> > > 
> > > 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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