[PATCH v2 10/19] system/memory: Default to guest_memfd for RAM for in-place conversion

[Michael Roth <michael.roth@amd.com>]

memory_region_init_ram_guest_memfd_private() is called in some cases
(legacy BIOS regions / IGVM regions) to allocate a new RAM region with a
guest_memfd FD under the covers to handle private memory since the GPA
range can be converted between shared/private guest RAM.

When in-place conversion is enabled, the conversions happen with the
guest_memfd inode itself, so the same inode must be used for both shared
and private memory. Handle this accordingly when convert-in-place=true.

Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 system/memory.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/system/memory.c b/system/memory.c
index b3b678617b..ba3ef27b58 100644
--- a/system/memory.c
+++ b/system/memory.c
@@ -3623,10 +3623,27 @@ bool memory_region_init_ram_guest_memfd_private(MemoryRegion *mr,
                                                 uint64_t size,
                                                 Error **errp)
 {
-    if (!memory_region_init_ram_flags_nomigrate(mr, owner, name, size,
-                                                RAM_GUEST_MEMFD_PRIVATE, errp)) {
-        return false;
+    if (machine_require_guest_memfd_convert_in_place(current_machine)) {
+        int fd = kvm_create_guest_memfd(size, errp);
+        if (fd < 0) {
+            return false;
+        }
+
+        if (!memory_region_init_ram_from_fd(mr, owner, name, size,
+                                            RAM_SHARED |
+                                            RAM_GUEST_MEMFD_PRIVATE |
+                                            RAM_GUEST_MEMFD_SHARED,
+                                            fd, 0, errp)) {
+            close(fd);
+            return false;
+        }
+    } else {
+        if (!memory_region_init_ram_flags_nomigrate(mr, owner, name, size,
+                                                    RAM_GUEST_MEMFD_PRIVATE, errp)) {
+            return false;
+        }
     }
+
     memory_region_register_ram(mr, owner);
     return true;
 }
-- 
2.43.0