After CXL completes trimming SOFT RESERVED ranges that intersect with CXL regions, it invokes hmem_fallback_register_device() to register any leftover ranges. If this occurs before the DAX HMEM driver has initialized, the call becomes a no-op and those resources are lost.
To prevent this, store fallback-registered resources in a separate deferred tree (hmem_deferred_active). When the DAX HMEM driver is initialized, it walks this deferred list to properly register DAX devices. Signed-off-by: Smita Koralahalli <[email protected]> --- drivers/dax/hmem/device.c | 17 +++++++++++++---- drivers/dax/hmem/hmem.c | 1 - drivers/dax/hmem/hmem_notify.c | 2 ++ 3 files changed, 15 insertions(+), 5 deletions(-) diff --git a/drivers/dax/hmem/device.c b/drivers/dax/hmem/device.c index cc1ed7bbdb1a..41c5886a30d1 100644 --- a/drivers/dax/hmem/device.c +++ b/drivers/dax/hmem/device.c @@ -16,13 +16,21 @@ static struct resource hmem_active = { .flags = IORESOURCE_MEM, }; +static struct resource hmem_deferred_active = { + .name = "Deferred HMEM devices", + .start = 0, + .end = -1, + .flags = IORESOURCE_MEM, +}; +static struct resource *hmem_resource_root = &hmem_active; + int walk_hmem_resources(walk_hmem_fn fn) { struct resource *res; int rc = 0; mutex_lock(&hmem_resource_lock); - for (res = hmem_active.child; res; res = res->sibling) { + for (res = hmem_resource_root->child; res; res = res->sibling) { rc = fn((int) res->desc, res); if (rc) break; @@ -36,8 +44,8 @@ static void __hmem_register_resource(int target_nid, struct resource *res) { struct resource *new; - new = __request_region(&hmem_active, res->start, resource_size(res), "", - 0); + new = __request_region(hmem_resource_root, res->start, + resource_size(res), "", 0); if (!new) { pr_debug("hmem range %pr already active\n", res); return; @@ -72,7 +80,8 @@ static __init int hmem_init(void) walk_iomem_res_desc(IORES_DESC_SOFT_RESERVED, IORESOURCE_MEM, 0, -1, NULL, hmem_register_one); - } + } else + hmem_resource_root = &hmem_deferred_active; pdev = platform_device_alloc("hmem_platform", 0); if (!pdev) { diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c index 16873ae0a53b..76a381c274a8 100644 --- a/drivers/dax/hmem/hmem.c +++ b/drivers/dax/hmem/hmem.c @@ -131,7 +131,6 @@ static int dax_hmem_platform_probe(struct platform_device *pdev) if (IS_ENABLED(CONFIG_CXL_ACPI)) { hmem_register_fallback_handler(hmem_register_device); - return 0; } return walk_hmem_resources(hmem_register_device); diff --git a/drivers/dax/hmem/hmem_notify.c b/drivers/dax/hmem/hmem_notify.c index 1b366ffbda66..6c276c5bd51d 100644 --- a/drivers/dax/hmem/hmem_notify.c +++ b/drivers/dax/hmem/hmem_notify.c @@ -23,5 +23,7 @@ void hmem_fallback_register_device(int target_nid, const struct resource *res) if (hmem_fn) hmem_fn(target_nid, res); + else + hmem_register_resource(target_nid, (struct resource *)res); } EXPORT_SYMBOL_GPL(hmem_fallback_register_device); -- 2.17.1
