intel_iommu: allow migration

IOMMU needs to be migrated before all the PCI devices (in case there are
devices that will request for address translation). So marking it with a
priority higher than the default (which PCI devices and other belong).
Migration framework handled the rest.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/intel_iommu.c

@@ -1996,7 +1996,27 @@ static void vtd_iommu_notify_flag_changed(MemoryRegion *iommu,
 
 static const VMStateDescription vtd_vmstate = {
     .name = "iommu-intel",
-    .unmigratable = 1,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .priority = MIG_PRI_IOMMU,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(root, IntelIOMMUState),
+        VMSTATE_UINT64(intr_root, IntelIOMMUState),
+        VMSTATE_UINT64(iq, IntelIOMMUState),
+        VMSTATE_UINT32(intr_size, IntelIOMMUState),
+        VMSTATE_UINT16(iq_head, IntelIOMMUState),
+        VMSTATE_UINT16(iq_tail, IntelIOMMUState),
+        VMSTATE_UINT16(iq_size, IntelIOMMUState),
+        VMSTATE_UINT16(next_frcd_reg, IntelIOMMUState),
+        VMSTATE_UINT8_ARRAY(csr, IntelIOMMUState, DMAR_REG_SIZE),
+        VMSTATE_UINT8(iq_last_desc_type, IntelIOMMUState),
+        VMSTATE_BOOL(root_extended, IntelIOMMUState),
+        VMSTATE_BOOL(dmar_enabled, IntelIOMMUState),
+        VMSTATE_BOOL(qi_enabled, IntelIOMMUState),
+        VMSTATE_BOOL(intr_enabled, IntelIOMMUState),
+        VMSTATE_BOOL(intr_eime, IntelIOMMUState),
+        VMSTATE_END_OF_LIST()
+    }
 };
 
 static const MemoryRegionOps vtd_mem_ops = {

include/migration/vmstate.h

@@ -188,6 +188,7 @@ enum VMStateFlags {
 
 typedef enum {
     MIG_PRI_DEFAULT = 0,
+    MIG_PRI_IOMMU,              /* Must happen before PCI devices */
     MIG_PRI_MAX,
 } MigrationPriority;