hw/arm_gic: Correctly restore nested irq priority

Upon activating an interrupt, set the corresponding priority bit in the
APR/NSAPR registers without touching the currently set bits. In the event
of nested interrupts, the GIC will then have the information it needs to
restore the priority of the pre-empted interrupt once the higher priority
interrupt finishes execution.

Signed-off-by: François Baldassari <francois@pebble.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
index d71aeb8..13e297d 100644 (file)
--- a/hw/intc/arm_gic.c
+++ b/hw/intc/arm_gic.c
@@ -254,9 +254,9 @@ static void gic_activate_irq(GICState *s, int cpu, int irq)
     int bitno = preemption_level % 32;
 
     if (gic_has_groups(s) && GIC_TEST_GROUP(irq, (1 << cpu))) {
-        s->nsapr[regno][cpu] &= (1 << bitno);
+        s->nsapr[regno][cpu] |= (1 << bitno);
     } else {
-        s->apr[regno][cpu] &= (1 << bitno);
+        s->apr[regno][cpu] |= (1 << bitno);
     }
 
     s->running_priority[cpu] = prio;