[PATCH v2 3/3] hw/cxl: Check for multiple mappings of memory backends.

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

Similar protection to that provided for -numa memdev=x
to make sure that memory used to back a type3 device is not also mapped
as normal RAM, or for multiple type3 devices.

This is an easy footgun to remove and seems multiple people have
run into it.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 hw/mem/cxl_type3.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
index 35ac59883a..e7fbbb4d51 100644
--- a/hw/mem/cxl_type3.c
+++ b/hw/mem/cxl_type3.c
@@ -737,6 +737,11 @@ static bool cxl_setup_memory(CXLType3Dev *ct3d, Error **errp)
             error_setg(errp, "volatile memdev must have backing device");
             return false;
         }
+        if (host_memory_backend_is_mapped(ct3d->hostvmem)) {
+            error_setg(errp, "memory backend %s can't be used multiple times.",
+               object_get_canonical_path_component(OBJECT(ct3d->hostvmem)));
+            return false;
+        }
         memory_region_set_nonvolatile(vmr, false);
         memory_region_set_enabled(vmr, true);
         host_memory_backend_set_mapped(ct3d->hostvmem, true);
@@ -760,6 +765,11 @@ static bool cxl_setup_memory(CXLType3Dev *ct3d, Error **errp)
             error_setg(errp, "persistent memdev must have backing device");
             return false;
         }
+        if (host_memory_backend_is_mapped(ct3d->hostpmem)) {
+            error_setg(errp, "memory backend %s can't be used multiple times.",
+               object_get_canonical_path_component(OBJECT(ct3d->hostpmem)));
+            return false;
+        }
         memory_region_set_nonvolatile(pmr, true);
         memory_region_set_enabled(pmr, true);
         host_memory_backend_set_mapped(ct3d->hostpmem, true);
@@ -790,6 +800,11 @@ static bool cxl_setup_memory(CXLType3Dev *ct3d, Error **errp)
             return false;
         }
 
+        if (host_memory_backend_is_mapped(ct3d->dc.host_dc)) {
+            error_setg(errp, "memory backend %s can't be used multiple times.",
+               object_get_canonical_path_component(OBJECT(ct3d->dc.host_dc)));
+            return false;
+        }
         /*
          * Set DC regions as volatile for now, non-volatile support can
          * be added in the future if needed.
-- 
2.43.0