Introduce new flag RAM_DEFAULT_PRIVATE for RAMBlock. It's used to
indicate the default attribute,  private or not.

Set the RAM range to private explicitly when it's default private.

Originated-from: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
 accel/kvm/kvm-all.c   | 10 ++++++++++
 include/exec/memory.h |  6 ++++++
 system/memory.c       | 13 +++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index a92fff471b58..316690d113d0 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -1467,6 +1467,16 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
                     strerror(-err));
             abort();
         }
+
+        if (memory_region_is_default_private(mr)) {
+            err = kvm_set_memory_attributes_private(start_addr, slot_size);
+            if (err) {
+                error_report("%s: failed to set memory attribute private: %s\n",
+                             __func__, strerror(-err));
+                exit(1);
+            }
+        }
+
         start_addr += slot_size;
         ram_start_offset += slot_size;
         ram += slot_size;
diff --git a/include/exec/memory.h b/include/exec/memory.h
index f780367ab1bd..bdc4b98efe70 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -246,6 +246,9 @@ typedef struct IOMMUTLBEvent {
 /* RAM can be private that has kvm gmem backend */
 #define RAM_GUEST_MEMFD   (1 << 12)
 
+/* RAM is default private */
+#define RAM_DEFAULT_PRIVATE     (1 << 13)
+
 static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
                                        IOMMUNotifierFlag flags,
                                        hwaddr start, hwaddr end,
@@ -1715,6 +1718,9 @@ bool memory_region_is_protected(MemoryRegion *mr);
  */
 bool memory_region_has_guest_memfd(MemoryRegion *mr);
 
+void memory_region_set_default_private(MemoryRegion *mr);
+bool memory_region_is_default_private(MemoryRegion *mr);
+
 /**
  * memory_region_get_iommu: check whether a memory region is an iommu
  *
diff --git a/system/memory.c b/system/memory.c
index 69741d91bbb7..b0c58232b6f7 100644
--- a/system/memory.c
+++ b/system/memory.c
@@ -1867,6 +1867,19 @@ bool memory_region_has_guest_memfd(MemoryRegion *mr)
     return mr->ram_block && mr->ram_block->guest_memfd >= 0;
 }
 
+bool memory_region_is_default_private(MemoryRegion *mr)
+{
+    return memory_region_has_guest_memfd(mr) &&
+           (mr->ram_block->flags & RAM_DEFAULT_PRIVATE);
+}
+
+void memory_region_set_default_private(MemoryRegion *mr)
+{
+    if (memory_region_has_guest_memfd(mr)) {
+        mr->ram_block->flags |= RAM_DEFAULT_PRIVATE;
+    }
+}
+
 uint8_t memory_region_get_dirty_log_mask(MemoryRegion *mr)
 {
     uint8_t mask = mr->dirty_log_mask;
-- 
2.34.1