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)
- DEFINE_IDTENTRY_RAW(exc_nmi_noist)
+ #if IS_ENABLED(CONFIG_KVM_INTEL)
+ DEFINE_IDTENTRY_RAW(exc_nmi_kvm_vmx)
{
exc_nmi(regs);
}
- #endif
#if IS_MODULE(CONFIG_KVM_INTEL)
- EXPORT_SYMBOL_GPL(asm_exc_nmi_noist);
+ EXPORT_SYMBOL_GPL(asm_exc_nmi_kvm_vmx);
+ #endif
#endif
+#ifdef CONFIG_NMI_CHECK_CPU
+
+static char *nmi_check_stall_msg[] = {
+/* */
+/* +--------- nsp->idt_seq_snap & 0x1: CPU is in NMI handler. */
+/* | +------ cpu_is_offline(cpu) */
+/* | | +--- nsp->idt_calls_snap != atomic_long_read(&nsp->idt_calls): */
+/* | | | NMI handler has been invoked. */
+/* | | | */
+/* V V V */
+/* 0 0 0 */ "NMIs are not reaching exc_nmi() handler",
+/* 0 0 1 */ "exc_nmi() handler is ignoring NMIs",
+/* 0 1 0 */ "CPU is offline and NMIs are not reaching exc_nmi() handler",
+/* 0 1 1 */ "CPU is offline and exc_nmi() handler is legitimately ignoring NMIs",
+/* 1 0 0 */ "CPU is in exc_nmi() handler and no further NMIs are reaching handler",
+/* 1 0 1 */ "CPU is in exc_nmi() handler which is legitimately ignoring NMIs",
+/* 1 1 0 */ "CPU is offline in exc_nmi() handler and no more NMIs are reaching exc_nmi() handler",
+/* 1 1 1 */ "CPU is offline in exc_nmi() handler which is legitimately ignoring NMIs",
+};
+
+void nmi_backtrace_stall_snap(const struct cpumask *btp)
+{
+ int cpu;
+ struct nmi_stats *nsp;
+
+ for_each_cpu(cpu, btp) {
+ nsp = per_cpu_ptr(&nmi_stats, cpu);
+ nsp->idt_seq_snap = READ_ONCE(nsp->idt_seq);
+ nsp->idt_nmi_seq_snap = READ_ONCE(nsp->idt_nmi_seq);
+ nsp->idt_ignored_snap = READ_ONCE(nsp->idt_ignored);
+ nsp->idt_calls_snap = atomic_long_read(&nsp->idt_calls);
+ }
+}
+
+void nmi_backtrace_stall_check(const struct cpumask *btp)
+{
+ int cpu;
+ int idx;
+ unsigned long nmi_seq;
+ unsigned long j = jiffies;
+ char *modp;
+ char *msgp;
+ char *msghp;
+ struct nmi_stats *nsp;
+
+ for_each_cpu(cpu, btp) {
+ nsp = per_cpu_ptr(&nmi_stats, cpu);
+ modp = "";
+ msghp = "";
+ nmi_seq = READ_ONCE(nsp->idt_nmi_seq);
+ if (nsp->idt_nmi_seq_snap + 1 == nmi_seq && (nmi_seq & 0x1)) {
+ msgp = "CPU entered NMI handler function, but has not exited";
+ } else if ((nsp->idt_nmi_seq_snap & 0x1) != (nmi_seq & 0x1)) {
+ msgp = "CPU is handling NMIs";
+ } else {
+ idx = ((nsp->idt_seq_snap & 0x1) << 2) |
+ (cpu_is_offline(cpu) << 1) |
+ (nsp->idt_calls_snap != atomic_long_read(&nsp->idt_calls));
+ msgp = nmi_check_stall_msg[idx];
+ if (nsp->idt_ignored_snap != READ_ONCE(nsp->idt_ignored) && (idx & 0x1))
+ modp = ", but OK because ignore_nmis was set";
+ if (nmi_seq & ~0x1)
+ msghp = " (CPU currently in NMI handler function)";
+ else if (nsp->idt_nmi_seq_snap + 1 == nmi_seq)
+ msghp = " (CPU exited one NMI handler function)";
+ }
+ pr_alert("%s: CPU %d: %s%s%s, last activity: %lu jiffies ago.\n",
+ __func__, cpu, msgp, modp, msghp, j - READ_ONCE(nsp->recv_jiffies));
+ }
+}
+
+#endif
+
void stop_nmi(void)
{
ignore_nmis++;