x86/amd-iommu: Fix PCI hotplug with passthrough mode

The device change notifier is initialized in the dma_ops
initialization path. But this path is never executed for
iommu=pt. Move the notifier initialization to IOMMU hardware
init code to fix this.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

arch/x86/include/asm/amd_iommu_proto.h

@@ -30,6 +30,7 @@ extern void amd_iommu_apply_erratum_63(u16 devid);
 extern void amd_iommu_reset_cmd_buffer(struct amd_iommu *iommu);
 extern int amd_iommu_init_devices(void);
 extern void amd_iommu_uninit_devices(void);
+extern void amd_iommu_init_notifier(void);
 #ifndef CONFIG_AMD_IOMMU_STATS
 
 static inline void amd_iommu_stats_init(void) { }

arch/x86/kernel/amd_iommu.c

@@ -1624,6 +1624,11 @@ static struct notifier_block device_nb = {
 	.notifier_call = device_change_notifier,
 };
 
+void amd_iommu_init_notifier(void)
+{
+	bus_register_notifier(&pci_bus_type, &device_nb);
+}
+
 /*****************************************************************************
  *
  * The next functions belong to the dma_ops mapping/unmapping code.
@@ -2250,8 +2255,6 @@ int __init amd_iommu_init_dma_ops(void)
 
 	register_iommu(&amd_iommu_ops);
 
-	bus_register_notifier(&pci_bus_type, &device_nb);
-
 	amd_iommu_stats_init();
 
 	return 0;

arch/x86/kernel/amd_iommu_init.c

@@ -1285,6 +1285,8 @@ static int __init amd_iommu_init(void)
 	if (ret)
 		goto free;
 
+	amd_iommu_init_notifier();
+
 	enable_iommus();
 
 	if (iommu_pass_through)