hw/intc/arm_gicv3_its: Implement full reset

Voiding the ITS caches is not supposed to happen via
individual register writes. So we introduced a dedicated
ITS KVM device ioctl to perform a cold reset of the ITS:
KVM_DEV_ARM_VGIC_GRP_CTRL/KVM_DEV_ARM_ITS_CTRL_RESET. Let's
use this latter if the kernel supports it.
Signed-off-by: NEric Auger <eric.auger@redhat.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1511883692-11511-5-git-send-email-eric.auger@redhat.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/intc/arm_gicv3_its_kvm.c

@@ -204,7 +204,14 @@ static void kvm_arm_its_reset(DeviceState *dev)
 
     c->parent_reset(dev);
 
-    error_report("ITS KVM: full reset is not supported by QEMU");
+    if (kvm_device_check_attr(s->dev_fd, KVM_DEV_ARM_VGIC_GRP_CTRL,
+                               KVM_DEV_ARM_ITS_CTRL_RESET)) {
+        kvm_device_access(s->dev_fd, KVM_DEV_ARM_VGIC_GRP_CTRL,
+                          KVM_DEV_ARM_ITS_CTRL_RESET, NULL, true, &error_abort);
+        return;
+    }
+
+    error_report("ITS KVM: full reset is not supported by the host kernel");
 
     if (!kvm_device_check_attr(s->dev_fd, KVM_DEV_ARM_VGIC_GRP_ITS_REGS,
                                GITS_CTLR)) {