[PATCH] arm/xen: Initialize event channels earlier

[Julien Grall]

Event channels driver needs to be initialized very early. Until now, Xen
initialization was done after all CPUs was bring up.

We can safely move the initialization to an early initcall.

Also use a cpu notifier to:
    - Register the VCPU when the CPU is prepared
    - Enable event channel IRQ when the CPU is running

Signed-off-by: Julien Grall <julien.grall at linaro.org>
---
 arch/arm/xen/enlighten.c |   84 ++++++++++++++++++++++++++++++----------------
 1 file changed, 55 insertions(+), 29 deletions(-)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 293eeea..39b668e 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -23,6 +23,7 @@
 #include <linux/of_address.h>
 #include <linux/cpuidle.h>
 #include <linux/cpufreq.h>
+#include <linux/cpu.h>
 
 #include <linux/mm.h>
 
@@ -154,12 +155,11 @@ int xen_unmap_domain_mfn_range(struct vm_area_struct *vma,
 }
 EXPORT_SYMBOL_GPL(xen_unmap_domain_mfn_range);
 
-static void __init xen_percpu_init(void *unused)
+static void xen_percpu_init(int cpu)
 {
 	struct vcpu_register_vcpu_info info;
 	struct vcpu_info *vcpup;
 	int err;
-	int cpu = get_cpu();
 
 	pr_info("Xen: initializing cpu%d\n", cpu);
 	vcpup = per_cpu_ptr(xen_vcpu_info, cpu);
@@ -170,9 +170,11 @@ static void __init xen_percpu_init(void *unused)
 	err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, cpu, &info);
 	BUG_ON(err);
 	per_cpu(xen_vcpu, cpu) = vcpup;
+}
 
+static void xen_interrupt_init(void)
+{
 	enable_percpu_irq(xen_events_irq, 0);
-	put_cpu();
 }
 
 static void xen_restart(enum reboot_mode reboot_mode, const char *cmd)
@@ -193,6 +195,36 @@ static void xen_power_off(void)
 		BUG();
 }
 
+static irqreturn_t xen_arm_callback(int irq, void *arg)
+{
+	xen_hvm_evtchn_do_upcall();
+	return IRQ_HANDLED;
+}
+
+static int xen_cpu_notification(struct notifier_block *self,
+				unsigned long action,
+				void *hcpu)
+{
+	int cpu = (long)hcpu;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		xen_percpu_init(cpu);
+		break;
+	case CPU_STARTING:
+		xen_interrupt_init();
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block xen_cpu_notifier = {
+	.notifier_call = xen_cpu_notification,
+};
+
 /*
  * see Documentation/devicetree/bindings/arm/xen.txt for the
  * documentation of the Xen Device Tree format.
@@ -209,6 +241,7 @@ static int __init xen_guest_init(void)
 	const char *xen_prefix = "xen,xen-";
 	struct resource res;
 	phys_addr_t grant_frames;
+	int cpu;
 
 	node = of_find_compatible_node(NULL, NULL, "xen,xen");
 	if (!node) {
@@ -281,9 +314,27 @@ static int __init xen_guest_init(void)
 	disable_cpuidle();
 	disable_cpufreq();
 
+	xen_init_IRQ();
+
+	if (xen_events_irq < 0)
+		return -ENODEV;
+
+	if (request_percpu_irq(xen_events_irq, xen_arm_callback,
+			       "events", &xen_vcpu)) {
+		pr_err("Error request IRQ %d\n", xen_events_irq);
+		return -EINVAL;
+	}
+
+	cpu = get_cpu();
+	xen_percpu_init(cpu);
+	xen_interrupt_init();
+	put_cpu();
+
+	register_cpu_notifier(&xen_cpu_notifier);
+
 	return 0;
 }
-core_initcall(xen_guest_init);
+early_initcall(xen_guest_init);
 
 static int __init xen_pm_init(void)
 {
@@ -297,31 +348,6 @@ static int __init xen_pm_init(void)
 }
 late_initcall(xen_pm_init);
 
-static irqreturn_t xen_arm_callback(int irq, void *arg)
-{
-	xen_hvm_evtchn_do_upcall();
-	return IRQ_HANDLED;
-}
-
-static int __init xen_init_events(void)
-{
-	if (!xen_domain() || xen_events_irq < 0)
-		return -ENODEV;
-
-	xen_init_IRQ();
-
-	if (request_percpu_irq(xen_events_irq, xen_arm_callback,
-			"events", &xen_vcpu)) {
-		pr_err("Error requesting IRQ %d\n", xen_events_irq);
-		return -EINVAL;
-	}
-
-	on_each_cpu(xen_percpu_init, NULL, 0);
-
-	return 0;
-}
-postcore_initcall(xen_init_events);
-
 /* In the hypervisor.S file. */
 EXPORT_SYMBOL_GPL(HYPERVISOR_event_channel_op);
 EXPORT_SYMBOL_GPL(HYPERVISOR_grant_table_op);
-- 
1.7.10.4