[RFC PATCH 4/6] memory: Register the RamDiscardManager instance upon guest_memfd creation

[Chenyi Qiang <chenyi.qiang@xxxxxxxxx>]

Instantiate a new guest_memfd_manager object and register it in the
target MemoryRegion. From this point, other subsystems such as VFIO can
register their listeners in guest_memfd_manager and receive conversion
events through RamDiscardManager.

Signed-off-by: Chenyi Qiang <chenyi.qiang@xxxxxxxxx>
---
 system/physmem.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/system/physmem.c b/system/physmem.c
index 33d09f7571..98072ae246 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -53,6 +53,7 @@
 #include "sysemu/hostmem.h"
 #include "sysemu/hw_accel.h"
 #include "sysemu/xen-mapcache.h"
+#include "sysemu/guest-memfd-manager.h"
 #include "trace/trace-root.h"
 
 #ifdef CONFIG_FALLOCATE_PUNCH_HOLE
@@ -1861,6 +1862,12 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
             qemu_mutex_unlock_ramlist();
             goto out_free;
         }
+
+        GuestMemfdManager *gmm = GUEST_MEMFD_MANAGER(object_new(TYPE_GUEST_MEMFD_MANAGER));
+        GuestMemfdManagerClass *gmmc = GUEST_MEMFD_MANAGER_GET_CLASS(gmm);
+        g_assert(new_block->mr);
+        gmmc->realize(OBJECT(gmm), new_block->mr, new_block->mr->size);
+        memory_region_set_ram_discard_manager(gmm->mr, RAM_DISCARD_MANAGER(gmm));
     }
 
     new_ram_size = MAX(old_ram_size,
@@ -2118,6 +2125,8 @@ static void reclaim_ramblock(RAMBlock *block)
 
     if (block->guest_memfd >= 0) {
         close(block->guest_memfd);
+        g_assert(block->mr);
+        object_unref(OBJECT(block->mr->rdm));
         ram_block_discard_require(false);
     }
 
-- 
2.43.5