>From 4fe7614f2087117aa912fd3d33d43ba02f2b50b1 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Thu, 11 Mar 2021 11:40:21 -0500
Subject: [PATCH] memory: Make sure root MR won't be added as subregion

Add a bool for MR to mark whether this MR is a root MR of an AS.  We bail out
asap if this MR is added as a subregion of another MR.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/exec/memory.h | 1 +
 softmmu/memory.c      | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index c6fb714e499..211f10e877e 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -477,6 +477,7 @@ struct MemoryRegion {
     bool ram_device;
     bool enabled;
     bool warning_printed; /* For reservations */
+    bool is_root_mr;
     uint8_t vga_logging_count;
     MemoryRegion *alias;
     hwaddr alias_offset;
diff --git a/softmmu/memory.c b/softmmu/memory.c
index 874a8fccdee..aebaa956258 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -2442,6 +2442,7 @@ static void memory_region_add_subregion_common(MemoryRegion *mr,
                                                MemoryRegion *subregion)
 {
     assert(!subregion->container);
+    assert(!subregion->is_root_mr);
     subregion->container = mr;
     subregion->addr = offset;
     memory_region_update_container_subregions(subregion);
@@ -2819,6 +2820,7 @@ void address_space_init(AddressSpace *as, MemoryRegion *root, const char *name)
 {
     memory_region_ref(root);
     as->root = root;
+    root->is_root_mr = true;
     as->current_map = NULL;
     as->ioeventfd_nb = 0;
     as->ioeventfds = NULL;
-- 
2.26.2