Hi Philippe,
On 2021/5/27 21:44, Philippe Mathieu-Daudé wrote:
On 5/27/21 2:31 PM, Kunkun Jiang wrote:
In the vfio_migration_init(), the SaveVMHandler is registered for
VFIO device. But it lacks the operation of 'unregister'. It will
lead to 'Segmentation fault (core dumped)' in
qemu_savevm_state_setup(), if performing live migration after a
VFIO device is hot deleted.
Fixes: 7c2f5f75f94 (vfio: Register SaveVMHandlers for VFIO device)
Reported-by: Qixin Gan <[email protected]>
Signed-off-by: Kunkun Jiang <[email protected]>
Cc: [email protected]
---
hw/vfio/migration.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 201642d75e..ef397ebe6c 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -892,6 +892,7 @@ void vfio_migration_finalize(VFIODevice *vbasedev)
remove_migration_state_change_notifier(&migration->migration_state);
qemu_del_vm_change_state_handler(migration->vm_state);
+ unregister_savevm(VMSTATE_IF(vbasedev->dev), "vfio", vbasedev);
Hmm what about devices using "%s/vfio" id?
The unregister_savevm() needs 'VMSTATEIf *obj'. If we pass a non-null 'obj'
to unregister_svevm(), it will handle the devices using "%s/vfio" id with
the following code:
if (obj) {
char *oid = vmstate_if_get_id(obj);
if (oid) {
pstrcpy(id, sizeof(id), oid);
pstrcat(id, sizeof(id), "/");
g_free(oid);
}
}
pstrcat(id, sizeof(id), idstr);
By the way, I'm puzzled that register_savevm_live() and unregister_savevm()
handle devices using "%s/vfio" id differently. So I learned the commit
history of register_savevm_live() and unregister_savevm().
In the beginning, both them need 'DeviceState *dev', which are replaced
with VMStateIf in 3cad405babb. Later in ce62df5378b, the 'dev' was removed,
because no caller of register_savevm_live() need to pass a non-null 'dev'
at that time.
So now the vfio devices need to handle the 'id' first and then call
register_savevm_live(). I am wondering whether we need to add
'VMSTATEIf *obj' in register_savevm_live(). What do you think of this?
Thanks,
Kunkun Jiang
vfio_migration_exit(vbasedev);
}
.
