From: Dan Williams <[email protected]>
Ensure that cxl_acpi has published CXL Window resources before dax_hmem
walks Soft Reserved ranges.
Replace MODULE_SOFTDEP("pre: cxl_acpi") with an explicit, synchronous
request_module("cxl_acpi"). MODULE_SOFTDEP() only guarantees eventual
loading, it does not enforce that the dependency has finished init
before the current module runs. This can cause dax_hmem to start before
cxl_acpi has populated the resource tree, breaking detection of overlaps
between Soft Reserved and CXL Windows.
Also, request cxl_pci before dax_hmem walks Soft Reserved ranges. Unlike
cxl_acpi, cxl_pci attach is asynchronous and creates dependent devices
that trigger further module loads. Asynchronous probe flushing
(wait_for_device_probe()) is added later in the series in a deferred
context before dax_hmem makes ownership decisions for Soft Reserved
ranges.
Add an additional explicit Kconfig ordering so that CXL_ACPI and CXL_PCI
must be initialized before DEV_DAX_HMEM. This prevents dax_hmem from
consuming Soft Reserved ranges before CXL drivers have had a chance to
claim them.
Signed-off-by: Dan Williams <[email protected]>
Signed-off-by: Smita Koralahalli <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
---
drivers/dax/Kconfig | 2 ++
drivers/dax/hmem/hmem.c | 17 ++++++++++-------
2 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
index d656e4c0eb84..3683bb3f2311 100644
--- a/drivers/dax/Kconfig
+++ b/drivers/dax/Kconfig
@@ -48,6 +48,8 @@ config DEV_DAX_CXL
tristate "CXL DAX: direct access to CXL RAM regions"
depends on CXL_BUS && CXL_REGION && DEV_DAX
default CXL_REGION && DEV_DAX
+ depends on CXL_ACPI >= DEV_DAX_HMEM
+ depends on CXL_PCI >= DEV_DAX_HMEM
help
CXL RAM regions are either mapped by platform-firmware
and published in the initial system-memory map as "System RAM", mapped
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 48f4642f4bb8..02e79c7adf75 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -141,6 +141,16 @@ static __init int dax_hmem_init(void)
{
int rc;
+ /*
+ * Ensure that cxl_acpi and cxl_pci have a chance to kick off
+ * CXL topology discovery at least once before scanning the
+ * iomem resource tree for IORES_DESC_CXL resources.
+ */
+ if (IS_ENABLED(CONFIG_DEV_DAX_CXL)) {
+ request_module("cxl_acpi");
+ request_module("cxl_pci");
+ }
+
rc = platform_driver_register(&dax_hmem_platform_driver);
if (rc)
return rc;
@@ -161,13 +171,6 @@ static __exit void dax_hmem_exit(void)
module_init(dax_hmem_init);
module_exit(dax_hmem_exit);
-/* Allow for CXL to define its own dax regions */
-#if IS_ENABLED(CONFIG_CXL_REGION)
-#if IS_MODULE(CONFIG_CXL_ACPI)
-MODULE_SOFTDEP("pre: cxl_acpi");
-#endif
-#endif
-
MODULE_ALIAS("platform:hmem*");
MODULE_ALIAS("platform:hmem_platform*");
MODULE_DESCRIPTION("HMEM DAX: direct access to 'specific purpose' memory");
--
2.17.1
