x86/irq: Call chip->irq_set_affinity in proper context

commit e23b257c293ce4bcc8cabb2aa3097b6ed8a8261a upstream.

setup_ioapic_dest() calls irqchip->irq_set_affinity() completely
unprotected. That's wrong in several aspects:

 - it opens a race window where irq_set_affinity() can be interrupted and the
   irq chip left in unconsistent state.

 - it triggers a lockdep splat when we fix the vector race for 4.3+ because
   vector lock is taken with interrupts enabled.

The proper calling convention is irq descriptor lock held and interrupts
disabled.

Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jeremiah Mahler <jmmahler@gmail.com>
Cc: andy.shevchenko@gmail.com
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Joe Lawrence <joe.lawrence@stratus.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1601140919420.3575@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 81e08eff05eedbd2e839a14229464cbea456e84c..9b0a93bfc80033c708602050ff492b64346e830a 100644 (file)
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3538,6 +3538,7 @@ void __init setup_ioapic_dest(void)
 {
        int pin, ioapic, irq, irq_entry;
        const struct cpumask *mask;
+       struct irq_desc *desc;
        struct irq_data *idata;
 
        if (skip_ioapic_setup == 1)
@@ -3553,7 +3554,9 @@ void __init setup_ioapic_dest(void)
                if ((ioapic > 0) && (irq > 16))
                        continue;
 
-               idata = irq_get_irq_data(irq);
+               desc = irq_to_desc(irq);
+               raw_spin_lock_irq(&desc->lock);
+               idata = irq_desc_get_irq_data(desc);
 
                /*
                 * Honour affinities which have been set in early boot
@@ -3564,6 +3567,7 @@ void __init setup_ioapic_dest(void)
                        mask = apic->target_cpus();
 
                x86_io_apic_ops.set_affinity(idata, mask, false);
+               raw_spin_unlock_irq(&desc->lock);
        }
 
 }