[Qemu-devel] [PATCH RFC 1/2] memory: make MemoryRegion alias migratable

[Igor Mammedov <imammedo@redhat.com>]

use qemu_ram_alloc_from_ptr() to create aliased RAMBlock
to the part of original memory region.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 exec.c   | 7 ++++---
 memory.c | 5 +++++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/exec.c b/exec.c
index 3e78de3b8f..daef0cd54f 100644
--- a/exec.c
+++ b/exec.c
@@ -2313,7 +2313,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp, bool shared)
                                         new_block->used_length,
                                         DIRTY_CLIENTS_ALL);
 
-    if (new_block->host) {
+    if (new_block->host && !new_block->mr->alias) {
         qemu_ram_setup_dump(new_block->host, new_block->max_length);
         qemu_madvise(new_block->host, new_block->max_length, QEMU_MADV_HUGEPAGE);
         /* MADV_DONTFORK is also needed by KVM in absence of synchronous MMU */
@@ -2671,7 +2671,8 @@ RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
 
     rcu_read_lock();
     block = atomic_rcu_read(&ram_list.mru_block);
-    if (block && block->host && host - block->host < block->max_length) {
+    if (block && !block->mr->alias && block->host &&
+        host - block->host < block->max_length) {
         goto found;
     }
 
@@ -2680,7 +2681,7 @@ RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
         if (block->host == NULL) {
             continue;
         }
-        if (host - block->host < block->max_length) {
+        if (!block->mr->alias && host - block->host < block->max_length) {
             goto found;
         }
     }
diff --git a/memory.c b/memory.c
index 5d8c9a9234..d710c17a26 100644
--- a/memory.c
+++ b/memory.c
@@ -1678,6 +1678,11 @@ void memory_region_init_alias(MemoryRegion *mr,
     memory_region_init(mr, owner, name, size);
     mr->alias = orig;
     mr->alias_offset = offset;
+    if (orig->ram_block && size) {
+        mr->ram_block = qemu_ram_alloc_from_ptr(size,
+                                                orig->ram_block->host + offset,
+                                                mr, &error_fatal);
+    }
 }
 
 void memory_region_init_rom_nomigrate(MemoryRegion *mr,
-- 
2.18.1