[PATCH 3/3] powerpc/pseries: implement nmi ipi with H_SIGNAL_SYS_RESET

[Nicholas Piggin]

H_SIGNAL_SYS_RESET can provide a hard NMI (it is not recoverable if
raised when the target has MSR_RI clear).

This patch makes a couple of changes to generic system_reset_exception
handler, which should be split out and platforms defining a handler
audited.
---
 arch/powerpc/kernel/traps.c          |  7 +++++--
 arch/powerpc/platforms/pseries/ras.c |  4 ++++
 arch/powerpc/platforms/pseries/smp.c | 12 +++++++++++-
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 023a462..d1d7fd4 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -275,19 +275,22 @@ void _exception(int signr, struct pt_regs *regs, int 
code, unsigned long addr)
 
 void system_reset_exception(struct pt_regs *regs)
 {
+       nmi_enter();
+
        /* See if any machine dependent calls */
        if (ppc_md.system_reset_exception) {
                if (ppc_md.system_reset_exception(regs))
-                       return;
+                       goto done;
        }
 
        die("System Reset", regs, SIGABRT);
 
+done:
        /* Must die if the interrupt is not recoverable */
        if (!(regs->msr & MSR_RI))
                panic("Unrecoverable System Reset");
 
-       /* What should we do here? We could issue a shutdown or hard reset. */
+       nmi_exit();
 }
 
 #ifdef CONFIG_PPC64
diff --git a/arch/powerpc/platforms/pseries/ras.c 
b/arch/powerpc/platforms/pseries/ras.c
index 904a677..bb70b26 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -386,6 +386,10 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
                }
                fwnmi_release_errinfo();
        }
+
+       if (smp_handle_nmi_ipi(regs))
+               return 1;
+
        return 0; /* need to perform reset */
 }
 
diff --git a/arch/powerpc/platforms/pseries/smp.c 
b/arch/powerpc/platforms/pseries/smp.c
index 0f6522c..4534c5a 100644
--- a/arch/powerpc/platforms/pseries/smp.c
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -196,6 +196,16 @@ static void pSeries_cause_ipi_mux(int cpu, unsigned long 
data)
                xics_cause_ipi(cpu, data);
 }
 
+static int pseries_cause_nmi_ipi(int cpu, int type)
+{
+       if (type == SMP_OP_NMI_TYPE_HARD) {
+               if (plapr_signal_sys_reset(cpu) == H_SUCCESS)
+                       return 1;
+       }
+
+       return 0;
+}
+
 static __init void pSeries_smp_probe(void)
 {
        xics_smp_probe();
@@ -209,7 +219,7 @@ static __init void pSeries_smp_probe(void)
 static struct smp_ops_t pseries_smp_ops = {
        .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
        .cause_ipi      = NULL, /* Filled at runtime by pSeries_smp_probe() */
-       .cause_nmi_ipi  = NULL,
+       .cause_nmi_ipi  = pseries_cause_nmi_ipi,
        .probe          = pSeries_smp_probe,
        .kick_cpu       = smp_pSeries_kick_cpu,
        .setup_cpu      = smp_setup_cpu,
-- 
2.10.2