xen/arm: Initialize correctly IRQ routing

When Xen initialize the GIC distributor, we need to route all the IRQs to
the boot CPU. The CPU ID can differ between Xen and the GIC.

When ITARGETSR0 is read, each field will return a value that corresponds
only to the processor reading the register. So Xen can use the PPI 0 to
initialize correctly the routing.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

xen/arch/arm/gic.c

@@ -258,9 +258,10 @@ void gic_route_dt_irq(const struct dt_irq *irq, const cpumask_t *cpu_mask,
 static void __init gic_dist_init(void)
 {
     uint32_t type;
-    uint32_t cpumask = 1 << smp_processor_id();
+    uint32_t cpumask;
     int i;
 
+    cpumask = GICD[GICD_ITARGETSR] & 0xff;
     cpumask |= cpumask << 8;
     cpumask |= cpumask << 16;