KVM: arm/arm64: vgic-new: vgic_init: implement kvm_vgic_hyp_init

Implements kvm_vgic_hyp_init and vgic_probe function.
This uses the new firmware independent VGIC probing to support both ACPI
and DT based systems (code from Marc Zyngier).

The vgic_global struct is enriched with new fields populated
by those functions.

Signed-off-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>

virt/kvm/arm/vgic/vgic-init.c

@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2015, 2016 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/uaccess.h>
+#include <linux/interrupt.h>
+#include <linux/cpu.h>
+#include <linux/kvm_host.h>
+#include <kvm/arm_vgic.h>
+#include <asm/kvm_mmu.h>
+#include "vgic.h"
+
+/* GENERIC PROBE */
+
+static void vgic_init_maintenance_interrupt(void *info)
+{
+	enable_percpu_irq(kvm_vgic_global_state.maint_irq, 0);
+}
+
+static int vgic_cpu_notify(struct notifier_block *self,
+			   unsigned long action, void *cpu)
+{
+	switch (action) {
+	case CPU_STARTING:
+	case CPU_STARTING_FROZEN:
+		vgic_init_maintenance_interrupt(NULL);
+		break;
+	case CPU_DYING:
+	case CPU_DYING_FROZEN:
+		disable_percpu_irq(kvm_vgic_global_state.maint_irq);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block vgic_cpu_nb = {
+	.notifier_call = vgic_cpu_notify,
+};
+
+static irqreturn_t vgic_maintenance_handler(int irq, void *data)
+{
+	/*
+	 * We cannot rely on the vgic maintenance interrupt to be
+	 * delivered synchronously. This means we can only use it to
+	 * exit the VM, and we perform the handling of EOIed
+	 * interrupts on the exit path (see vgic_process_maintenance).
+	 */
+	return IRQ_HANDLED;
+}
+
+/**
+ * kvm_vgic_hyp_init: populates the kvm_vgic_global_state variable
+ * according to the host GIC model. Accordingly calls either
+ * vgic_v2/v3_probe which registers the KVM_DEVICE that can be
+ * instantiated by a guest later on .
+ */
+int kvm_vgic_hyp_init(void)
+{
+	const struct gic_kvm_info *gic_kvm_info;
+	int ret;
+
+	gic_kvm_info = gic_get_kvm_info();
+	if (!gic_kvm_info)
+		return -ENODEV;
+
+	if (!gic_kvm_info->maint_irq) {
+		kvm_err("No vgic maintenance irq\n");
+		return -ENXIO;
+	}
+
+	switch (gic_kvm_info->type) {
+	case GIC_V2:
+		ret = vgic_v2_probe(gic_kvm_info);
+		break;
+	case GIC_V3:
+		ret = vgic_v3_probe(gic_kvm_info);
+		break;
+	default:
+		ret = -ENODEV;
+	};
+
+	if (ret)
+		return ret;
+
+	kvm_vgic_global_state.maint_irq = gic_kvm_info->maint_irq;
+	ret = request_percpu_irq(kvm_vgic_global_state.maint_irq,
+				 vgic_maintenance_handler,
+				 "vgic", kvm_get_running_vcpus());
+	if (ret) {
+		kvm_err("Cannot register interrupt %d\n",
+			kvm_vgic_global_state.maint_irq);
+		return ret;
+	}
+
+	ret = __register_cpu_notifier(&vgic_cpu_nb);
+	if (ret) {
+		kvm_err("Cannot register vgic CPU notifier\n");
+		goto out_free_irq;
+	}
+
+	on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
+
+	kvm_info("vgic interrupt IRQ%d\n", kvm_vgic_global_state.maint_irq);
+	return 0;
+
+out_free_irq:
+	free_percpu_irq(kvm_vgic_global_state.maint_irq,
+			kvm_get_running_vcpus());
+	return ret;
+}