@@ -1310,10 +1310,9 @@ masked_##_H##interrupt: \
stb r11,PACAIRQHAPPENED(r13); \
cmpwi r10,PACA_IRQ_DEC; \
bne 1f; \
- lis r10,0x7fff; \
- ori r10,r10,0xffff; \
- mtspr SPRN_DEC,r10; \
- b 2f; \
+ GET_SCRATCH0(r10); \
+ std r13,PACA_EXGEN+EX_R13(r13); \
+ EXCEPTION_PROLOG_PSERIES_1(handle_nmi_dec, _H); \
1: cmpwi r10,PACA_IRQ_DBELL; \
beq 2f; \
cmpwi r10,PACA_IRQ_HMI; \
@@ -1337,6 +1336,7 @@ USE_FIXED_SECTION(virt_trampolines)
MASKED_INTERRUPT(H)
EXC_COMMON(handle_irq_mask, 0x500, handle_masked_irq)
+EXC_COMMON(handle_nmi_dec, 0x900, handle_soft_nmi)
#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
TRAMP_REAL_BEGIN(kvmppc_skip_interrupt)
@@ -118,6 +118,7 @@ struct clock_event_device decrementer_clockevent = {
EXPORT_SYMBOL(decrementer_clockevent);
DEFINE_PER_CPU(u64, decrementers_next_tb);
+DEFINE_PER_CPU(u64, nmi_started_tb);
static DEFINE_PER_CPU(struct clock_event_device, decrementers);
#define XSEC_PER_SEC (1024*1024)
@@ -520,6 +521,7 @@ static void __timer_interrupt(void)
u64 now;
trace_timer_interrupt_entry(regs);
+ __this_cpu_write(nmi_started_tb, 0);
if (test_irq_work_pending()) {
clear_irq_work_pending();
@@ -565,6 +567,7 @@ void timer_interrupt(struct pt_regs * regs)
* some CPUs will continue to take decrementer exceptions.
*/
set_dec(decrementer_max);
+ __this_cpu_write(nmi_started_tb, 0);
/* Some implementations of hotplug will get timer interrupts while
* offline, just ignore these and we also need to set
@@ -599,6 +602,28 @@ EXPORT_SYMBOL(timer_interrupt);
/*
+ * If we have watchdog enabled, we do expect to hit this
+ * at-least once per sample_frequence.
+ * We set the decrement to 30 seconds and if we hit it
+ * again.. it's a BUG, it can be made a NMI panic as well.
+ */
+void handle_soft_nmi(struct pt_regs *regs)
+{
+ unsigned long long now = get_tb_or_rtc();
+ unsigned long long nmi_started_time = __this_cpu_read(nmi_started_tb);
+
+ if (!nmi_started_time) {
+ set_dec(ppc_tb_freq);
+ __this_cpu_write(nmi_started_tb, now);
+ } else {
+ if ((now - nmi_started_time) >= (30 * ppc_tb_freq)) {
+ BUG_ON(1);
+ } else
+ set_dec(ppc_tb_freq);
+ }
+}
+
+/*
* Hypervisor decrementer interrupts shouldn't occur but are sometimes
* left pending on exit from a KVM guest. We don't need to do anything
* to clear them, as they are edge-triggered.
a. On decrementer interrupt, instead of setting dec to maximum and returning, we do the following i. Call a function handle_nmi_dec, which in turn calls handle_soft_nmi ii. handle_soft_nmi sets the decrementer value to 1 second and checks if more than 30 seconds have passed since starting it. If so it calls BUG_ON(1), we can do an NMI panic as well. This patch relies on the previous patch to keep interrupts enabled and held at the previous priority (not EOI'd) when we disable interrupts. Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Balbir Singh <bsingharora@gmail.com> --- arch/powerpc/kernel/exceptions-64s.S | 8 ++++---- arch/powerpc/kernel/time.c | 25 +++++++++++++++++++++++++ 2 files changed, 29 insertions(+), 4 deletions(-)