[PATCH V1 25/26] migration: fix mismatched GPAs during cpr-exec

[Steve Sistare]

For cpr-exec mode, ramblock_is_ignored is always true, and the address of
each migrated memory region must match the address of the statically
initialized region on the target.  However, for a PCI rom block, the region
address is set when the guest writes to a BAR on the source, which does not
occur on the target, causing a "Mismatched GPAs" error during cpr-exec
migration.

To fix, unconditionally set the target's address to the source's address
if the region does not have an address yet.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 include/exec/memory.h | 12 ++++++++++++
 migration/ram.c       | 15 +++++++++------
 system/memory.c       | 10 ++++++++--
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index d337737..4f654b0 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -801,6 +801,7 @@ struct MemoryRegion {
     bool unmergeable;
     uint8_t dirty_log_mask;
     bool is_iommu;
+    bool has_addr;
     RAMBlock *ram_block;
     Object *owner;
     /* owner as TYPE_DEVICE. Used for re-entrancy checks in MR access hotpath 
*/
@@ -2402,6 +2403,17 @@ void memory_region_set_enabled(MemoryRegion *mr, bool 
enabled);
 void memory_region_set_address(MemoryRegion *mr, hwaddr addr);
 
 /*
+ * memory_region_set_address_only: set the address of a region.
+ *
+ * Same as memory_region_set_address, but without causing transaction side
+ * effects.
+ *
+ * @mr: the region to be updated
+ * @addr: new address, relative to container region
+ */
+void memory_region_set_address_only(MemoryRegion *mr, hwaddr addr);
+
+/*
  * memory_region_set_size: dynamically update the size of a region.
  *
  * Dynamically updates the size of a region.
diff --git a/migration/ram.c b/migration/ram.c
index add285b..7b8d7f6 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -4196,12 +4196,15 @@ static int parse_ramblock(QEMUFile *f, RAMBlock *block, 
ram_addr_t length)
     }
     if (migrate_ignore_shared()) {
         hwaddr addr = qemu_get_be64(f);
-        if (migrate_ram_is_ignored(block) &&
-            block->mr->addr != addr) {
-            error_report("Mismatched GPAs for block %s "
-                         "%" PRId64 "!= %" PRId64, block->idstr,
-                         (uint64_t)addr, (uint64_t)block->mr->addr);
-            return -EINVAL;
+        if (migrate_ram_is_ignored(block)) {
+            if (!block->mr->has_addr) {
+                memory_region_set_address_only(block->mr, addr);
+            } else if (block->mr->addr != addr) {
+                error_report("Mismatched GPAs for block %s "
+                             "%" PRId64 "!= %" PRId64, block->idstr,
+                             (uint64_t)addr, (uint64_t)block->mr->addr);
+                return -EINVAL;
+            }
         }
     }
     ret = rdma_block_notification_handle(f, block->idstr);
diff --git a/system/memory.c b/system/memory.c
index ca04a0e..3c72504 100644
--- a/system/memory.c
+++ b/system/memory.c
@@ -2665,7 +2665,7 @@ static void 
memory_region_add_subregion_common(MemoryRegion *mr,
     for (alias = subregion->alias; alias; alias = alias->alias) {
         alias->mapped_via_alias++;
     }
-    subregion->addr = offset;
+    memory_region_set_address_only(subregion, offset);
     memory_region_update_container_subregions(subregion);
 }
 
@@ -2745,10 +2745,16 @@ static void memory_region_readd_subregion(MemoryRegion 
*mr)
     }
 }
 
+void memory_region_set_address_only(MemoryRegion *mr, hwaddr addr)
+{
+    mr->addr = addr;
+    mr->has_addr = true;
+}
+
 void memory_region_set_address(MemoryRegion *mr, hwaddr addr)
 {
     if (addr != mr->addr) {
-        mr->addr = addr;
+        memory_region_set_address_only(mr, addr);
         memory_region_readd_subregion(mr);
     }
 }
-- 
1.8.3.1