[PATCH 3.4 107/146] xen/events: don't bind non-percpu VIRQs with percpu chip

From: lizf
Date: Tue Sep 15 2015 - 05:24:28 EST


From: David Vrabel <david.vrabel@xxxxxxxxxx>

3.4.109-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit 77bb3dfdc0d554befad58fdefbc41be5bc3ed38a upstream.

A non-percpu VIRQ (e.g., VIRQ_CONSOLE) may be freed on a different
VCPU than it is bound to. This can result in a race between
handle_percpu_irq() and removing the action in __free_irq() because
handle_percpu_irq() does not take desc->lock. The interrupt handler
sees a NULL action and oopses.

Only use the percpu chip/handler for per-CPU VIRQs (like VIRQ_TIMER).

# cat /proc/interrupts | grep virq
40: 87246 0 xen-percpu-virq timer0
44: 0 0 xen-percpu-virq debug0
47: 0 20995 xen-percpu-virq timer1
51: 0 0 xen-percpu-virq debug1
69: 0 0 xen-dyn-virq xen-pcpu
74: 0 0 xen-dyn-virq mce
75: 29 0 xen-dyn-virq hvc_console

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
[lizf: Backported to 3.4: adjust filename]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
drivers/tty/hvc/hvc_xen.c | 2 +-
drivers/xen/events.c | 12 ++++++++----
include/xen/events.h | 2 +-
3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 53e02b7..160b1f3 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -290,7 +290,7 @@ static int xen_initial_domain_console_init(void)
return -ENOMEM;
}

- info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
+ info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
info->vtermno = HVC_COOKIE;

spin_lock(&xencons_lock);
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index fdf842c..d6e2dee 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -906,7 +906,7 @@ static int find_virq(unsigned int virq, unsigned int cpu)
return rc;
}

-int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
+int bind_virq_to_irq(unsigned int virq, unsigned int cpu, bool percpu)
{
struct evtchn_bind_virq bind_virq;
int evtchn, irq, ret;
@@ -920,8 +920,12 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
if (irq == -1)
goto out;

- irq_set_chip_and_handler_name(irq, &xen_percpu_chip,
- handle_percpu_irq, "virq");
+ if (percpu)
+ irq_set_chip_and_handler_name(irq, &xen_percpu_chip,
+ handle_percpu_irq, "virq");
+ else
+ irq_set_chip_and_handler_name(irq, &xen_dynamic_chip,
+ handle_edge_irq, "virq");

bind_virq.virq = virq;
bind_virq.vcpu = cpu;
@@ -1042,7 +1046,7 @@ int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
{
int irq, retval;

- irq = bind_virq_to_irq(virq, cpu);
+ irq = bind_virq_to_irq(virq, cpu, irqflags & IRQF_PERCPU);
if (irq < 0)
return irq;
retval = request_irq(irq, handler, irqflags, devname, dev_id);
diff --git a/include/xen/events.h b/include/xen/events.h
index 04399b2..f9cb630 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -12,7 +12,7 @@ int bind_evtchn_to_irqhandler(unsigned int evtchn,
irq_handler_t handler,
unsigned long irqflags, const char *devname,
void *dev_id);
-int bind_virq_to_irq(unsigned int virq, unsigned int cpu);
+int bind_virq_to_irq(unsigned int virq, unsigned int cpu, bool percpu);
int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
irq_handler_t handler,
unsigned long irqflags, const char *devname,
--
1.9.1

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