[MODERATED] [PATCH v6 18/43] MDSv6

[Andi Kleen <andi@firstfloor.org>]

From: Andi Kleen <ak@linux.intel.com>
Subject:  mds: Support cpu clear in interrupts

According to an audit the majority of interrupt handlers
do not touch user data.

But some do. Add a IRQ_F_USER_DATA flag to enable
clearing after an interrupt.

Future patches will add this flag to interrupts
that need it.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 include/linux/interrupt.h | 2 ++
 kernel/irq/handle.c       | 4 ++++
 kernel/irq/manage.c       | 1 +
 3 files changed, 7 insertions(+)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 4a728dba02e2..0f8ddb7ba09b 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -61,6 +61,7 @@
  *                interrupt handler after suspending interrupts. For system
  *                wakeup devices users need to implement wakeup detection in
  *                their interrupt handlers.
+ * IRQF_USER_DATA - Interrupt does touch user data
  */
 #define IRQF_SHARED		0x00000080
 #define IRQF_PROBE_SHARED	0x00000100
@@ -74,6 +75,7 @@
 #define IRQF_NO_THREAD		0x00010000
 #define IRQF_EARLY_RESUME	0x00020000
 #define IRQF_COND_SUSPEND	0x00040000
+#define IRQF_USER_DATA		0x00080000
 
 #define IRQF_TIMER		(__IRQF_TIMER | IRQF_NO_SUSPEND | IRQF_NO_THREAD)
 
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 38554bc35375..46895311e849 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -13,6 +13,7 @@
 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
+#include <linux/clearcpu.h>
 
 #include <trace/events/irq.h>
 
@@ -149,6 +150,9 @@ irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags
 		res = action->handler(irq, action->dev_id);
 		trace_irq_handler_exit(irq, action, res);
 
+		if (action->flags & IRQF_USER_DATA)
+			lazy_clear_cpu();
+
 		if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pF enabled interrupts\n",
 			      irq, action->handler))
 			local_irq_disable();
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 84b54a17b95d..d1de8d797fc8 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1796,6 +1796,7 @@ EXPORT_SYMBOL(free_irq);
  *
  *	IRQF_SHARED		Interrupt is shared
  *	IRQF_TRIGGER_*		Specify active edge(s) or level
+ *	IRQF_USER_DATA		Handler touches user data with CPU.
  *
  */
 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
-- 
2.17.2