[PATCH] x86: add IRQ context simulation in module mce-inject

[Luck, Tony]

mce-inject provides a mechanism to simulate errors so that test
scripts can check for correct operation of the kernel without
requiring any specialized hardware to create rare events.

The existing code can simulate events in normal process context
and also in NMI context - but not in IRQ context. This patch
fills that gap.

Signed-off-by: Chen Gong <gong.chen@xxxxxxxxxxxxxxx>
Acked-by: Tony Luck <tony.luck@xxxxxxxxx>

---
[Re-wrote the commit comment - Chen Gong's original text is below,
 in case I missed any critical aspect - Tony]
module mce-inject is an interface which is used by user space app
such as mce-inject. According to it one can inject all kinds of
error combinations into the kernel. In this way, one can check
error condition coverage in the kernel. To satisify this needs,
module mce-inject must simulate enough scenarios such as process
context, IRQ context, even NMI context, to ensure related kernel
codes are strong and reliable. In current implementation, IRQ
context hasn't been simulated. This patch is for this purpose.

 arch/x86/include/asm/mce.h              |    9 ++++---
 arch/x86/kernel/cpu/mcheck/mce-inject.c |   34 +++++++++++++++++++++++++++---
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index c9321f3..312d770 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -50,10 +50,11 @@
 #define MCJ_CTX_MASK		3
 #define MCJ_CTX(flags)		((flags) & MCJ_CTX_MASK)
 #define MCJ_CTX_RANDOM		0    /* inject context: random */
-#define MCJ_CTX_PROCESS		1    /* inject context: process */
-#define MCJ_CTX_IRQ		2    /* inject context: IRQ */
-#define MCJ_NMI_BROADCAST	4    /* do NMI broadcasting */
-#define MCJ_EXCEPTION		8    /* raise as exception */
+#define MCJ_CTX_PROCESS		0x1  /* inject context: process */
+#define MCJ_CTX_IRQ		0x2  /* inject context: IRQ */
+#define MCJ_NMI_BROADCAST	0x4  /* do NMI broadcasting */
+#define MCJ_EXCEPTION		0x8  /* raise as exception */
+#define MCJ_IRQ_BRAODCAST	0x10 /* do IRQ broadcasting */
 
 /* Fields are zero when not available */
 struct mce {
diff --git a/arch/x86/kernel/cpu/mcheck/mce-inject.c b/arch/x86/kernel/cpu/mcheck/mce-inject.c
index 6199232..505461e 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-inject.c
+++ b/arch/x86/kernel/cpu/mcheck/mce-inject.c
@@ -17,6 +17,7 @@
 #include <linux/kernel.h>
 #include <linux/string.h>
 #include <linux/fs.h>
+#include <linux/preempt.h>
 #include <linux/smp.h>
 #include <linux/notifier.h>
 #include <linux/kdebug.h>
@@ -92,6 +93,18 @@ static int mce_raise_notify(unsigned int cmd, struct pt_regs *regs)
 	return NMI_HANDLED;
 }
 
+static void mce_irq_ipi(void *info)
+{
+	int cpu = smp_processor_id();
+	struct mce *m = &__get_cpu_var(injectm);
+
+	if (cpumask_test_cpu(cpu, mce_inject_cpumask) &&
+			m->inject_flags & MCJ_EXCEPTION) {
+		cpumask_clear_cpu(cpu, mce_inject_cpumask);
+		raise_exception(m, NULL);
+	}
+}
+
 /* Inject mce on current CPU */
 static int raise_local(void)
 {
@@ -139,9 +152,10 @@ static void raise_mce(struct mce *m)
 		return;
 
 #ifdef CONFIG_X86_LOCAL_APIC
-	if (m->inject_flags & MCJ_NMI_BROADCAST) {
+	if (m->inject_flags & (MCJ_IRQ_BRAODCAST | MCJ_NMI_BROADCAST)) {
 		unsigned long start;
 		int cpu;
+
 		get_online_cpus();
 		cpumask_copy(mce_inject_cpumask, cpu_online_mask);
 		cpumask_clear_cpu(get_cpu(), mce_inject_cpumask);
@@ -151,13 +165,25 @@ static void raise_mce(struct mce *m)
 			    MCJ_CTX(mcpu->inject_flags) != MCJ_CTX_RANDOM)
 				cpumask_clear_cpu(cpu, mce_inject_cpumask);
 		}
-		if (!cpumask_empty(mce_inject_cpumask))
-			apic->send_IPI_mask(mce_inject_cpumask, NMI_VECTOR);
+		if (!cpumask_empty(mce_inject_cpumask)) {
+			if (m->inject_flags & MCJ_IRQ_BRAODCAST) {
+				/*
+				 * don't wait because mce_irq_ipi is necessary
+				 * to be sync with following raise_local
+				 */
+				preempt_disable();
+				smp_call_function_many(mce_inject_cpumask,
+					mce_irq_ipi, NULL, 0);
+				preempt_enable();
+			} else if (m->inject_flags & MCJ_NMI_BROADCAST)
+				apic->send_IPI_mask(mce_inject_cpumask,
+						NMI_VECTOR);
+		}
 		start = jiffies;
 		while (!cpumask_empty(mce_inject_cpumask)) {
 			if (!time_before(jiffies, start + 2*HZ)) {
 				printk(KERN_ERR
-				"Timeout waiting for mce inject NMI %lx\n",
+				"Timeout waiting for mce inject %lx\n",
 					*cpumask_bits(mce_inject_cpumask));
 				break;
 			}
-- 
1.7.7.rc0.70.g82660

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