[PATCH v4 09/14] cxl/acpi: Prepare use of EFI runtime services

Robert Richter
2025-11-03T18:49:33Z

In order to use EFI runtime services, esp. ACPI PRM which uses the
efi_rts_wq workqueue, initialize EFI before CXL ACPI.

There is a subsys_initcall order dependency if driver is builtin:

subsys_initcall(cxl_acpi_init);
subsys_initcall(efisubsys_init);

Prevent the efi_rts_wq workqueue being used by cxl_acpi_init() before
its allocation. Use subsys_initcall_sync(cxl_acpi_init) to always run
efisubsys_init() first.

Reported-by: Gregory Price <gourry@gourry.net>
Tested-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Signed-off-by: Robert Richter <rrichter@amd.com>
---
drivers/cxl/acpi.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 1ab780edf141..a54d56376787 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -996,8 +996,12 @@ static void __exit cxl_acpi_exit(void)
cxl_bus_drain();
}

-/* load before dax_hmem sees 'Soft Reserved' CXL ranges */
-subsys_initcall(cxl_acpi_init);
+/*
+ * Load before dax_hmem sees 'Soft Reserved' CXL ranges. Use
+ * subsys_initcall_sync() since there is an order dependency with
+ * subsys_initcall(efisubsys_init), which must run first.
+ */
+subsys_initcall_sync(cxl_acpi_init);

/*
* Arrange for host-bridge ports to be active synchronous with
--
2.47.3