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

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>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1601140919420.3575@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 5 insertions, 1 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index f25321894ad2..fdb0fbfb1197 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/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