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

commit e23b257c 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@nanosSigned-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/x86/kernel/apic/io_apic.c

@@ -2521,6 +2521,7 @@ void __init setup_ioapic_dest(void)
 {
 	int pin, ioapic, irq, irq_entry;
 	const struct cpumask *mask;
+	struct irq_desc *desc;
 	struct irq_data *idata;
 	struct irq_chip *chip;
 
@@ -2536,7 +2537,9 @@ void __init setup_ioapic_dest(void)
 		if (irq < 0 || !mp_init_irq_at_boot(ioapic, irq))
 			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
@@ -2550,6 +2553,7 @@ void __init setup_ioapic_dest(void)
 		/* Might be lapic_chip for irq 0 */
 		if (chip->irq_set_affinity)
 			chip->irq_set_affinity(idata, mask, false);
+		raw_spin_unlock_irq(&desc->lock);
 	}
 }
 #endif