Commit 77bb3dfd authored by David Vrabel's avatar David Vrabel
Browse files

xen/events: don't bind non-percpu VIRQs with percpu chip 



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: default avatarDavid Vrabel <david.vrabel@citrix.com>
Cc: <stable@vger.kernel.org>
parent ffb7dbed

drivers/tty/hvc/hvc_xen.c

+1 −1
Original line number Diff line number Diff line
@@ -289,7 +289,7 @@ 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);

drivers/xen/events/events_base.c

+8 −4
Original line number Diff line number Diff line
@@ -957,7 +957,7 @@ unsigned xen_evtchn_nr_channels(void) 
}

EXPORT_SYMBOL_GPL(xen_evtchn_nr_channels);



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;
@@ -971,8 +971,12 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu) 
		if (irq < 0)

			goto out;



		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;
@@ -1062,7 +1066,7 @@ 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);

include/xen/events.h

+1 −1
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ 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,

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