CP-20679: cope when pgpu metadata is unobtainable

The code that fetched the pgpu metadata from the Nvidia driver was
assuming that this would always work for every GPU made by Nvidia.

In fact only some Nvidia GPUs support the feature, and even where
the feature is available, and the Nvidia driver has been installed
on the host, that Nvidia driver has not yet been loaded when xapi
starts on host boot.

Therefore this commit catches the exception
Gpumon_interface.NvmlInterfaceNotAvailable
and the exception handler returns and empty list for the metadata.

Signed-off-by: Thomas Sanders <[email protected]>

Author: thomassa

ocaml/xapi/xapi_pgpu.ml

@@ -38,9 +38,13 @@ let fetch_compatibility_metadata ~__context ~pgpu_pci =
      Xapi_gpumon.Nvidia.get_pgpu_compatibility_metadata ~dbg ~pgpu_pci_address
   ) else []
 
+let maybe_fetch_compatibility_metadata ~__context ~pgpu_pci =
+  try fetch_compatibility_metadata ~__context ~pgpu_pci
+  with Gpumon_interface.NvmlInterfaceNotAvailable -> []
+
 let populate_compatibility_metadata ~__context ~pgpu ~pgpu_pci =
   let () = Db.PGPU.set_compatibility_metadata ~__context ~self:pgpu
-    ~value:(fetch_compatibility_metadata ~__context ~pgpu_pci)
+    ~value:(maybe_fetch_compatibility_metadata ~__context ~pgpu_pci)
   in ()
 
 let create ~__context ~pCI ~gPU_group ~host ~other_config
@@ -55,7 +59,7 @@ let create ~__context ~pCI ~gPU_group ~host ~other_config
     ~gPU_group ~host ~other_config ~size
     ~supported_VGPU_max_capacities ~dom0_access
     ~is_system_display_device
-    ~compatibility_metadata:(fetch_compatibility_metadata ~__context ~pgpu_pci:pCI);
+    ~compatibility_metadata:(maybe_fetch_compatibility_metadata ~__context ~pgpu_pci:pCI);
   Db.PGPU.set_supported_VGPU_types ~__context
     ~self:pgpu ~value:supported_VGPU_types;
   Db.PGPU.set_enabled_VGPU_types ~__context