This is a note to let you know that I've just added the patch titled
cxl/mem: Fix no cxl_nvd during pmem region auto-assembling
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cxl-mem-fix-no-cxl_nvd-during-pmem-region-auto-assem.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 73e1be76584ca6235a9aff2625db0b780fa20934
Author: Li Ming <ming4.li@xxxxxxxxx>
Date: Wed Jun 12 14:44:23 2024 +0800
cxl/mem: Fix no cxl_nvd during pmem region auto-assembling
[ Upstream commit 84ec985944ef34a34a1605b93ce401aa8737af96 ]
When CXL subsystem is auto-assembling a pmem region during cxl
endpoint port probing, always hit below calltrace.
BUG: kernel NULL pointer dereference, address: 0000000000000078
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
RIP: 0010:cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem]
Call Trace:
<TASK>
? __die+0x24/0x70
? page_fault_oops+0x82/0x160
? do_user_addr_fault+0x65/0x6b0
? exc_page_fault+0x7d/0x170
? asm_exc_page_fault+0x26/0x30
? cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem]
? cxl_pmem_region_probe+0x1ac/0x360 [cxl_pmem]
cxl_bus_probe+0x1b/0x60 [cxl_core]
really_probe+0x173/0x410
? __pfx___device_attach_driver+0x10/0x10
__driver_probe_device+0x80/0x170
driver_probe_device+0x1e/0x90
__device_attach_driver+0x90/0x120
bus_for_each_drv+0x84/0xe0
__device_attach+0xbc/0x1f0
bus_probe_device+0x90/0xa0
device_add+0x51c/0x710
devm_cxl_add_pmem_region+0x1b5/0x380 [cxl_core]
cxl_bus_probe+0x1b/0x60 [cxl_core]
The cxl_nvd of the memdev needs to be available during the pmem region
probe. Currently the cxl_nvd is registered after the endpoint port probe.
The endpoint probe, in the case of autoassembly of regions, can cause a
pmem region probe requiring the not yet available cxl_nvd. Adjust the
sequence so this dependency is met.
This requires adding a port parameter to cxl_find_nvdimm_bridge() that
can be used to query the ancestor root port. The endpoint port is not
yet available, but will share a common ancestor with its parent, so
start the query from there instead.
Fixes: f17b558d6663 ("cxl/pmem: Refactor nvdimm device registration, delete the workqueue")
Co-developed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Li Ming <ming4.li@xxxxxxxxx>
Tested-by: Alison Schofield <alison.schofield@xxxxxxxxx>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Reviewed-by: Alison Schofield <alison.schofield@xxxxxxxxx>
Link: https://patch.msgid.link/20240612064423.2567625-1-ming4.li@xxxxxxxxx
Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c
index e69625a8d6a1d..c00f3a933164f 100644
--- a/drivers/cxl/core/pmem.c
+++ b/drivers/cxl/core/pmem.c
@@ -62,10 +62,14 @@ static int match_nvdimm_bridge(struct device *dev, void *data)
return is_cxl_nvdimm_bridge(dev);
}
-struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd)
+/**
+ * cxl_find_nvdimm_bridge() - find a bridge device relative to a port
+ * @port: any descendant port of an nvdimm-bridge associated
+ * root-cxl-port
+ */
+struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port)
{
- struct cxl_root *cxl_root __free(put_cxl_root) =
- find_cxl_root(cxlmd->endpoint);
+ struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
struct device *dev;
if (!cxl_root)
@@ -242,18 +246,20 @@ static void cxlmd_release_nvdimm(void *_cxlmd)
/**
* devm_cxl_add_nvdimm() - add a bridge between a cxl_memdev and an nvdimm
+ * @parent_port: parent port for the (to be added) @cxlmd endpoint port
* @cxlmd: cxl_memdev instance that will perform LIBNVDIMM operations
*
* Return: 0 on success negative error code on failure.
*/
-int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd)
+int devm_cxl_add_nvdimm(struct cxl_port *parent_port,
+ struct cxl_memdev *cxlmd)
{
struct cxl_nvdimm_bridge *cxl_nvb;
struct cxl_nvdimm *cxl_nvd;
struct device *dev;
int rc;
- cxl_nvb = cxl_find_nvdimm_bridge(cxlmd);
+ cxl_nvb = cxl_find_nvdimm_bridge(parent_port);
if (!cxl_nvb)
return -ENODEV;
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index bcb30e04e0963..857afc8b72ff1 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2712,7 +2712,7 @@ static int cxl_pmem_region_alloc(struct cxl_region *cxlr)
* bridge for one device is the same for all.
*/
if (i == 0) {
- cxl_nvb = cxl_find_nvdimm_bridge(cxlmd);
+ cxl_nvb = cxl_find_nvdimm_bridge(cxlmd->endpoint);
if (!cxl_nvb)
return -ENODEV;
cxlr->cxl_nvb = cxl_nvb;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 72fa477407689..2b82dcaf70aa6 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -848,8 +848,8 @@ struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host,
struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev);
bool is_cxl_nvdimm(struct device *dev);
bool is_cxl_nvdimm_bridge(struct device *dev);
-int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd);
-struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd);
+int devm_cxl_add_nvdimm(struct cxl_port *parent_port, struct cxl_memdev *cxlmd);
+struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port);
#ifdef CONFIG_CXL_REGION
bool is_cxl_pmem_region(struct device *dev);
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 0c79d9ce877cc..2f1b49bfe162f 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -152,6 +152,15 @@ static int cxl_mem_probe(struct device *dev)
return -ENXIO;
}
+ if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM)) {
+ rc = devm_cxl_add_nvdimm(parent_port, cxlmd);
+ if (rc) {
+ if (rc == -ENODEV)
+ dev_info(dev, "PMEM disabled by platform\n");
+ return rc;
+ }
+ }
+
if (dport->rch)
endpoint_parent = parent_port->uport_dev;
else
@@ -174,14 +183,6 @@ static int cxl_mem_probe(struct device *dev)
if (rc)
return rc;
- if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM)) {
- rc = devm_cxl_add_nvdimm(cxlmd);
- if (rc == -ENODEV)
- dev_info(dev, "PMEM disabled by platform\n");
- else
- return rc;
- }
-
/*
* The kernel may be operating out of CXL memory on this device,
* there is no spec defined way to determine whether this device
