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authorPaul E. McKenney <paulmck@kernel.org>2022-12-16 15:57:51 -0800
committerPaul E. McKenney <paulmck@kernel.org>2023-01-19 15:54:41 -0800
commit1a3ea611fc105759cf1023e922d00cf44569b8bb (patch)
tree4fef9a5d7ac343ee3c521a9abd6ebdf2ab40fa2d /arch/x86
parent1b929c02afd37871d5afb9d498426f83432e71c2 (diff)
x86/nmi: Accumulate NMI-progress evidence in exc_nmi()
CPUs ignoring NMIs is often a sign of those CPUs going bad, but there are quite a few other reasons why a CPU might ignore NMIs. Therefore, accumulate evidence within exc_nmi() as to what might be preventing a given CPU from responding to an NMI. [ paulmck: Apply Peter Zijlstra feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: <x86@kernel.org> Reviewed-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/nmi.c35
1 files changed, 34 insertions, 1 deletions
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index cec0bfa3bc04..701ff27a77ec 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -69,6 +69,15 @@ struct nmi_stats {
unsigned int unknown;
unsigned int external;
unsigned int swallow;
+ unsigned long recv_jiffies;
+ unsigned long idt_seq;
+ unsigned long idt_nmi_seq;
+ unsigned long idt_ignored;
+ atomic_long_t idt_calls;
+ unsigned long idt_seq_snap;
+ unsigned long idt_nmi_seq_snap;
+ unsigned long idt_ignored_snap;
+ long idt_calls_snap;
};
static DEFINE_PER_CPU(struct nmi_stats, nmi_stats);
@@ -479,12 +488,15 @@ static DEFINE_PER_CPU(unsigned long, nmi_dr7);
DEFINE_IDTENTRY_RAW(exc_nmi)
{
irqentry_state_t irq_state;
+ struct nmi_stats *nsp = this_cpu_ptr(&nmi_stats);
/*
* Re-enable NMIs right here when running as an SEV-ES guest. This might
* cause nested NMIs, but those can be handled safely.
*/
sev_es_nmi_complete();
+ if (IS_ENABLED(CONFIG_NMI_CHECK_CPU))
+ arch_atomic_long_inc(&nsp->idt_calls);
if (IS_ENABLED(CONFIG_SMP) && arch_cpu_is_offline(smp_processor_id()))
return;
@@ -495,6 +507,11 @@ DEFINE_IDTENTRY_RAW(exc_nmi)
}
this_cpu_write(nmi_state, NMI_EXECUTING);
this_cpu_write(nmi_cr2, read_cr2());
+ if (IS_ENABLED(CONFIG_NMI_CHECK_CPU)) {
+ WRITE_ONCE(nsp->idt_seq, nsp->idt_seq + 1);
+ WARN_ON_ONCE(!(nsp->idt_seq & 0x1));
+ WRITE_ONCE(nsp->recv_jiffies, jiffies);
+ }
nmi_restart:
/*
@@ -509,8 +526,19 @@ nmi_restart:
inc_irq_stat(__nmi_count);
- if (!ignore_nmis)
+ if (IS_ENABLED(CONFIG_NMI_CHECK_CPU) && ignore_nmis) {
+ WRITE_ONCE(nsp->idt_ignored, nsp->idt_ignored + 1);
+ } else if (!ignore_nmis) {
+ if (IS_ENABLED(CONFIG_NMI_CHECK_CPU)) {
+ WRITE_ONCE(nsp->idt_nmi_seq, nsp->idt_nmi_seq + 1);
+ WARN_ON_ONCE(!(nsp->idt_nmi_seq & 0x1));
+ }
default_do_nmi(regs);
+ if (IS_ENABLED(CONFIG_NMI_CHECK_CPU)) {
+ WRITE_ONCE(nsp->idt_nmi_seq, nsp->idt_nmi_seq + 1);
+ WARN_ON_ONCE(nsp->idt_nmi_seq & 0x1);
+ }
+ }
irqentry_nmi_exit(regs, irq_state);
@@ -525,6 +553,11 @@ nmi_restart:
if (user_mode(regs))
mds_user_clear_cpu_buffers();
+ if (IS_ENABLED(CONFIG_NMI_CHECK_CPU)) {
+ WRITE_ONCE(nsp->idt_seq, nsp->idt_seq + 1);
+ WARN_ON_ONCE(nsp->idt_seq & 0x1);
+ WRITE_ONCE(nsp->recv_jiffies, jiffies);
+ }
}
#if defined(CONFIG_X86_64) && IS_ENABLED(CONFIG_KVM_INTEL)