Debug keyhandlers for triggering an NMI and examine current NMI state.

Add 'N' keyhandler to dump the current per CPU NMI counts and the
current NMI mask/pending status.

Add 'n' keyhandler to trigger an NMI by sending an IPI. For some
reason the destination shorthand for self is not valid when used with
the NMI delivery mode so we send the IPI to our own APIC ID
explicitly.

Signed-off-by: Ian Campbell <Ian.Campbell@XenSource.com>

diff --git a/xen/arch/x86/nmi.c b/xen/arch/x86/nmi.c
index d2ccd4e7e498ac4ae23751f7280b60e43103a36e..f8c34a1c27b9213ca425d1b6e0f0730a76cdecf4 100644 (file)
--- a/xen/arch/x86/nmi.c
+++ b/xen/arch/x86/nmi.c
@@ -23,12 +23,14 @@
 #include <xen/sched.h>
 #include <xen/console.h>
 #include <xen/smp.h>
+#include <xen/keyhandler.h>
 #include <asm/current.h>
 #include <asm/mc146818rtc.h>
 #include <asm/msr.h>
 #include <asm/mpspec.h>
 #include <asm/debugger.h>
 #include <asm/div64.h>
+#include <asm/apic.h>
 
 unsigned int nmi_watchdog = NMI_NONE;
 static spinlock_t   watchdog_lock = SPIN_LOCK_UNLOCKED;
@@ -448,3 +450,26 @@ void nmi_watchdog_tick(struct cpu_user_regs * regs)
         write_watchdog_counter(NULL);
     }
 }
+
+/*
+ * For some reason the destination shorthand for self is not valid
+ * when used with the NMI delivery mode. This is documented in Tables
+ * 8-3 and 8-4 in IA32 Reference Manual Volume 3. We send the IPI to
+ * our own APIC ID explicitly which is valid.
+ */
+static void do_nmi_trigger(unsigned char key) {
+    u32 id = apic_read(APIC_ID);
+
+    printk("triggering NMI on APIC ID %x\n", id);
+
+    apic_wait_icr_idle();
+    apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(id));
+    apic_write_around(APIC_ICR, APIC_DM_NMI | APIC_INT_ASSERT);
+}
+
+static __init int register_nmi_trigger(void)
+{
+    register_keyhandler('n', do_nmi_trigger, "trigger an NMI");
+    return 0;
+}
+__initcall(register_nmi_trigger);

diff --git a/xen/common/keyhandler.c b/xen/common/keyhandler.c
index b239391462a6b6fea6ecb94066f5f8d5c43e6d9a..5fc1e6b04c1d184034bd224df1a50aec3c0cfaba 100644 (file)
--- a/xen/common/keyhandler.c
+++ b/xen/common/keyhandler.c
@@ -185,6 +185,27 @@ void do_debug_key(unsigned char key, struct cpu_user_regs *regs)
                              bit. */
 }
 
+void do_nmi_stats(unsigned char key)
+{
+    int i;
+    struct domain *d;
+    struct vcpu *v;
+    printk("CPU\tNMI\n");
+    for_each_cpu(i)
+        printk("%3d\t%3d\n", i, nmi_count(i));
+
+    if ((d = dom0) == NULL)
+        return;
+    if ((v = d->vcpu[0]) == NULL)
+        return;
+    if (v->vcpu_flags & (VCPUF_nmi_pending|VCPUF_nmi_masked))
+        printk("dom0 vpu0: NMI %s%s\n",
+               v->vcpu_flags & VCPUF_nmi_pending ? "pending " : "",
+               v->vcpu_flags & VCPUF_nmi_masked ? "masked " : "");
+    else
+        printk("dom0 vcpu0: NMI neither pending nor masked\n");
+}
+
 #ifndef NDEBUG
 void debugtrace_key(unsigned char key)
 {
@@ -213,6 +234,7 @@ void initialize_keytable(void)
         'r', dump_runq,      "dump run queues");
     register_irq_keyhandler(
         'R', halt_machine,   "reboot machine"); 
+    register_keyhandler('N', do_nmi_stats,   "NMI statistics");
 
 #ifndef NDEBUG
     register_keyhandler(