[PATCH v2 0/3] cxl: Format the device serial number as unsigned

[PATCH v2 0/3] cxl: Format the device serial number as unsigned

[Alison Schofield]

This series supersedes the previously posted standalone fix:
  cxl/pmem: Format nvdimm serial number as decimal

That patch addressed the immediate auto-unlock failure caused by the
kernel formatting the nvdimm security key description differently than
the decimal 'id' sysfs attribute used by ndctl.

Further review uncovered a second formatting issue affecting the same
serial number. The CXL device serial number is a u64 PCIe Device Serial
Number, yet several kernel interfaces format it with signed "%lld".
Devices whose vendor OUI sets bit 63 therefore appear with negative
decimal serial numbers.

Serials with bit 64 set are expected. The most significant byte of the
PCIe Device Serial Number contains the vendor OUI, so vendors such as
Montage naturally produce serial numbers with bit 63 set.

Rather than merge the decimal-format fix and immediately follow it with
another patch changing the same code to "%llu", fold both fixes into a
single series that consistently formats CXL serial numbers as unsigned
where appropriate and adds cxl_test coverage for the large serial case.


Alison Schofield (3):
  cxl/pmem: Format the nvdimm serial number as unsigned decimal
  cxl/core: Format the memdev serial number as unsigned in TP_printk
  cxl/test: Assign one mock memdev a full-width serial number

 Documentation/ABI/testing/sysfs-bus-nvdimm |  3 ++-
 drivers/cxl/core/pmem.c                    | 10 ++++++----
 drivers/cxl/core/trace.h                   | 10 +++++-----
 drivers/cxl/cxl.h                          |  3 ++-
 drivers/cxl/pmem.c                         |  2 +-
 tools/testing/cxl/test/mem.c               | 15 ++++++++++++++-
 6 files changed, 30 insertions(+), 13 deletions(-)


base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
-- 
2.37.3

[PATCH v2 1/3] cxl/pmem: Format the nvdimm serial number as unsigned decimal

[Alison Schofield]

The CXL NVDIMM security passphrase key description and the nvdimm 'id'
sysfs attribute are both derived from the CXL device serial number,
but the serial number is not formatted consistently.

The key description is formatted in hexadecimal while the 'id'
attribute is formatted in decimal. As a result, ndctl stores the key
using a decimal description while the kernel later looks it up using
a hexadecimal description. For serial numbers of 10 and above, the
descriptions no longer match, preventing automatic unlock after
reboot.

The decimal formatting has a second problem. Both the key description
and the 'id' attribute use the signed %lld format for a u64 PCIe
Device Serial Number. Devices whose vendor OUI sets bit 63, such as
Montage CXL devices, appear with negative decimal serial numbers.

Format the security key description and 'id' attribute as unsigned
decimal, %llu, and document that the 'id' attribute is an unsigned
decimal value.

The key lookup mismatch was exposed by CXL unit test cxl-security.sh
when cxl_test mock serial numbers were extended to 10 and above.

Cc: <stable@vger.kernel.org>
Fixes: b5807c80b5bc ("cxl: add dimm_id support for __nvdimm_create()")
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 Documentation/ABI/testing/sysfs-bus-nvdimm |  3 ++-
 drivers/cxl/core/pmem.c                    | 10 ++++++----
 drivers/cxl/cxl.h                          |  3 ++-
 drivers/cxl/pmem.c                         |  2 +-
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-nvdimm b/Documentation/ABI/testing/sysfs-bus-nvdimm
index 64eb8f4c6a41..46dafd8482b9 100644
--- a/Documentation/ABI/testing/sysfs-bus-nvdimm
+++ b/Documentation/ABI/testing/sysfs-bus-nvdimm
@@ -48,7 +48,8 @@ What:		/sys/bus/nd/devices/nmemX/cxl/id
 Date:		November 2022
 KernelVersion:	6.2
 Contact:	Dave Jiang <dave.jiang@intel.com>
-Description:	(RO) Show the id (serial) of the device. This is CXL specific.
+Description:	(RO) Show the id (serial) of the device, formatted as an
+		unsigned 64-bit decimal value. This is CXL specific.
 
 What:		/sys/bus/nd/devices/nmemX/cxl/provider
 Date:		November 2022
diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c
index 68462e38a977..5a3bb7e8a1f1 100644
--- a/drivers/cxl/core/pmem.c
+++ b/drivers/cxl/core/pmem.c
@@ -219,12 +219,14 @@ static struct cxl_nvdimm *cxl_nvdimm_alloc(struct cxl_nvdimm_bridge *cxl_nvb,
 	dev->bus = &cxl_bus_type;
 	dev->type = &cxl_nvdimm_type;
 	/*
-	 * A "%llx" string is 17-bytes vs dimm_id that is max
-	 * NVDIMM_KEY_DESC_LEN
+	 * dev_id is the nvdimm dimm_id used for security key lookup.
+	 * It must match id_show(), which emits the CXL serial as an
+	 * unsigned decimal. A u64 decimal string is at most 20 digits
+	 * plus NUL.
 	 */
-	BUILD_BUG_ON(sizeof(cxl_nvd->dev_id) < 17 ||
+	BUILD_BUG_ON(sizeof(cxl_nvd->dev_id) < 21 ||
 		     sizeof(cxl_nvd->dev_id) > NVDIMM_KEY_DESC_LEN);
-	sprintf(cxl_nvd->dev_id, "%llx", cxlmd->cxlds->serial);
+	sprintf(cxl_nvd->dev_id, "%llu", cxlmd->cxlds->serial);
 
 	return cxl_nvd;
 }
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index c0e5308e4d1b..d683ae5e0f7d 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -503,7 +503,8 @@ struct cxl_nvdimm_bridge {
 	struct nvdimm_bus_descriptor nd_desc;
 };
 
-#define CXL_DEV_ID_LEN 19
+/* Holds a u64 serial as a decimal string: up to 20 digits + NUL */
+#define CXL_DEV_ID_LEN 21
 
 enum {
 	CXL_NVD_F_INVALIDATED = 0,
diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
index 261dff7ced9f..a9f50281875d 100644
--- a/drivers/cxl/pmem.c
+++ b/drivers/cxl/pmem.c
@@ -52,7 +52,7 @@ static ssize_t id_show(struct device *dev, struct device_attribute *attr, char *
 	struct cxl_nvdimm *cxl_nvd = nvdimm_provider_data(nvdimm);
 	struct cxl_dev_state *cxlds = cxl_nvd->cxlmd->cxlds;
 
-	return sysfs_emit(buf, "%lld\n", cxlds->serial);
+	return sysfs_emit(buf, "%llu\n", cxlds->serial);
 }
 static DEVICE_ATTR_RO(id);
 
-- 
2.37.3

[PATCH v2 2/3] cxl/core: Format the memdev serial number as unsigned in TP_printk

[Alison Schofield]

The CXL memdev serial number is a u64 PCIe Device Serial Number, but
the tracepoints format it with %lld. Devices whose vendor OUI sets
bit 63 therefore appear with negative serial numbers in formatted
trace output.

Note that the trace data itself is already stored correctly as u64.

Format the TP_printk serial as unsigned decimal, %llu, to match the
underlying value.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 drivers/cxl/core/trace.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
index d37876096dd7..c379d60047fc 100644
--- a/drivers/cxl/core/trace.h
+++ b/drivers/cxl/core/trace.h
@@ -107,7 +107,7 @@ TRACE_EVENT(cxl_aer_uncorrectable_error,
 		memcpy(__entry->header_log, hl,
 			CXL_HEADERLOG_TRACE_SIZE_U32 * sizeof(u32));
 	),
-	TP_printk("memdev=%s host=%s serial=%lld: status: '%s' first_error: '%s'",
+	TP_printk("memdev=%s host=%s serial=%llu: status: '%s' first_error: '%s'",
 		  __get_str(memdev), __get_str(host), __entry->serial,
 		  show_uc_errs(__entry->status),
 		  show_uc_errs(__entry->first_error)
@@ -166,7 +166,7 @@ TRACE_EVENT(cxl_aer_correctable_error,
 		__entry->serial = cxlmd->cxlds->serial;
 		__entry->status = status;
 	),
-	TP_printk("memdev=%s host=%s serial=%lld: status: '%s'",
+	TP_printk("memdev=%s host=%s serial=%llu: status: '%s'",
 		  __get_str(memdev), __get_str(host), __entry->serial,
 		  show_ce_errs(__entry->status)
 	)
@@ -206,7 +206,7 @@ TRACE_EVENT(cxl_overflow,
 		__entry->last_ts = le64_to_cpu(payload->last_overflow_timestamp);
 	),
 
-	TP_printk("memdev=%s host=%s serial=%lld: log=%s : %u records from %llu to %llu",
+	TP_printk("memdev=%s host=%s serial=%llu: log=%s : %u records from %llu to %llu",
 		__get_str(memdev), __get_str(host), __entry->serial,
 		cxl_event_log_type_str(__entry->log), __entry->count,
 		__entry->first_ts, __entry->last_ts)
@@ -279,7 +279,7 @@ TRACE_EVENT(cxl_overflow,
 	__entry->hdr_head_id = (hdr).head_id
 
 #define CXL_EVT_TP_printk(fmt, ...) \
-	TP_printk("memdev=%s host=%s serial=%lld log=%s : time=%llu uuid=%pUb "	\
+	TP_printk("memdev=%s host=%s serial=%llu log=%s : time=%llu uuid=%pUb "	\
 		"len=%d flags='%s' handle=%x related_handle=%x "		\
 		"maint_op_class=%u maint_op_sub_class=%u "			\
 		"ld_id=%x head_id=%x : " fmt,					\
@@ -1088,7 +1088,7 @@ TRACE_EVENT(cxl_poison,
 		}
 	    ),
 
-	TP_printk("memdev=%s host=%s serial=%lld trace_type=%s region=%s "  \
+	TP_printk("memdev=%s host=%s serial=%llu trace_type=%s region=%s "  \
 		"region_uuid=%pU hpa=0x%llx hpa_alias0=0x%llx dpa=0x%llx " \
 		"dpa_length=0x%x source=%s flags=%s overflow_time=%llu",
 		__get_str(memdev),
-- 
2.37.3

[PATCH v2 3/3] cxl/test: Assign one mock memdev a full-width serial number

[Alison Schofield]

Mock memdev serial numbers have historically been derived from
pdev->id, leaving them single-digit. As a result they never exercised
either the decimal-vs-hex security-key lookup or unsigned formatting
of large serial numbers.

Give one mock memdev a full-width serial with bit 63 set. This mirrors
real hardware (for example, Montage devices) and provides a test
device that exposes both the hexadecimal-vs-decimal and signed-vs-
unsigned formatting differences.

This enables adding a new test case to cxl-security.sh that does an
auto-unlock using a mock device whose serial exposes both formatting
differences.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 tools/testing/cxl/test/mem.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index a1d170f88fee..42f5ffd29651 100644
--- a/tools/testing/cxl/test/mem.c
+++ b/tools/testing/cxl/test/mem.c
@@ -1714,6 +1714,7 @@ static int cxl_mock_mem_probe(struct platform_device *pdev)
 	struct cxl_mockmem_data *mdata;
 	struct cxl_mailbox *cxl_mbox;
 	struct cxl_dpa_info range_info = { 0 };
+	u64 serial;
 	int rc;
 
 	/* Increase async probe race window */
@@ -1740,7 +1741,19 @@ static int cxl_mock_mem_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
-	mds = cxl_memdev_state_create(dev, pdev->id + 1, 0);
+	/*
+	 * Mock serials have historically been derived from pdev->id and stayed
+	 * single-digit, so they never exercised either decimal-vs-hex key
+	 * lookup or unsigned formatting. Give one mock device a full-width
+	 * serial with bit 63 set, matching real hardware such as Montage CXL
+	 * devices. pdev->id 7 is unused by the auto-region topology.
+	 */
+	if (pdev->id == 7)
+		serial = 0x8a34567890abcdef;
+	else
+		serial = pdev->id + 1;
+
+	mds = cxl_memdev_state_create(dev, serial, 0);
 	if (IS_ERR(mds))
 		return PTR_ERR(mds);
 
-- 
2.37.3

Re: [PATCH v2 1/3] cxl/pmem: Format the nvdimm serial number as unsigned decimal

[Richard Cheng]

On Wed, Jul 01, 2026 at 05:30:44PM +0800, Alison Schofield wrote:
> The CXL NVDIMM security passphrase key description and the nvdimm 'id'
> sysfs attribute are both derived from the CXL device serial number,
> but the serial number is not formatted consistently.
> 
> The key description is formatted in hexadecimal while the 'id'
> attribute is formatted in decimal. As a result, ndctl stores the key
> using a decimal description while the kernel later looks it up using
> a hexadecimal description. For serial numbers of 10 and above, the
> descriptions no longer match, preventing automatic unlock after
> reboot.
> 
> The decimal formatting has a second problem. Both the key description
> and the 'id' attribute use the signed %lld format for a u64 PCIe
> Device Serial Number. Devices whose vendor OUI sets bit 63, such as
> Montage CXL devices, appear with negative decimal serial numbers.
> 
> Format the security key description and 'id' attribute as unsigned
> decimal, %llu, and document that the 'id' attribute is an unsigned
> decimal value.
> 
> The key lookup mismatch was exposed by CXL unit test cxl-security.sh
> when cxl_test mock serial numbers were extended to 10 and above.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: b5807c80b5bc ("cxl: add dimm_id support for __nvdimm_create()")
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> ---
>  Documentation/ABI/testing/sysfs-bus-nvdimm |  3 ++-
>  drivers/cxl/core/pmem.c                    | 10 ++++++----
>  drivers/cxl/cxl.h                          |  3 ++-
>  drivers/cxl/pmem.c                         |  2 +-
>  4 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-nvdimm b/Documentation/ABI/testing/sysfs-bus-nvdimm
> index 64eb8f4c6a41..46dafd8482b9 100644
> --- a/Documentation/ABI/testing/sysfs-bus-nvdimm
> +++ b/Documentation/ABI/testing/sysfs-bus-nvdimm
> @@ -48,7 +48,8 @@ What:		/sys/bus/nd/devices/nmemX/cxl/id
>  Date:		November 2022
>  KernelVersion:	6.2
>  Contact:	Dave Jiang <dave.jiang@intel.com>
> -Description:	(RO) Show the id (serial) of the device. This is CXL specific.
> +Description:	(RO) Show the id (serial) of the device, formatted as an
> +		unsigned 64-bit decimal value. This is CXL specific.
>  
>  What:		/sys/bus/nd/devices/nmemX/cxl/provider
>  Date:		November 2022
> diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c
> index 68462e38a977..5a3bb7e8a1f1 100644
> --- a/drivers/cxl/core/pmem.c
> +++ b/drivers/cxl/core/pmem.c
> @@ -219,12 +219,14 @@ static struct cxl_nvdimm *cxl_nvdimm_alloc(struct cxl_nvdimm_bridge *cxl_nvb,
>  	dev->bus = &cxl_bus_type;
>  	dev->type = &cxl_nvdimm_type;
>  	/*
> -	 * A "%llx" string is 17-bytes vs dimm_id that is max
> -	 * NVDIMM_KEY_DESC_LEN
> +	 * dev_id is the nvdimm dimm_id used for security key lookup.
> +	 * It must match id_show(), which emits the CXL serial as an
> +	 * unsigned decimal. A u64 decimal string is at most 20 digits
> +	 * plus NUL.
>  	 */
> -	BUILD_BUG_ON(sizeof(cxl_nvd->dev_id) < 17 ||
> +	BUILD_BUG_ON(sizeof(cxl_nvd->dev_id) < 21 ||
>  		     sizeof(cxl_nvd->dev_id) > NVDIMM_KEY_DESC_LEN);
> -	sprintf(cxl_nvd->dev_id, "%llx", cxlmd->cxlds->serial);
> +	sprintf(cxl_nvd->dev_id, "%llu", cxlmd->cxlds->serial);
> 

Hi Alison,

How should existing keys for high-bit serial numbers be migrated?

This patch changes both the sysfs  ID and kernel key description to unsigned
decimal. ndctl persists the old sysfs string in the key-blob filename and reloads it unchanged.

I wonder how's the old key being migrated ? I don't think the patch rename files under /etc/ndctl/keys , so ndctl may reload the existing secret
while the new kernel searches for the positive new label.

--Richard
 
>  	return cxl_nvd;
>  }
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index c0e5308e4d1b..d683ae5e0f7d 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -503,7 +503,8 @@ struct cxl_nvdimm_bridge {
>  	struct nvdimm_bus_descriptor nd_desc;
>  };
>  
> -#define CXL_DEV_ID_LEN 19
> +/* Holds a u64 serial as a decimal string: up to 20 digits + NUL */
> +#define CXL_DEV_ID_LEN 21
>  
>  enum {
>  	CXL_NVD_F_INVALIDATED = 0,
> diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
> index 261dff7ced9f..a9f50281875d 100644
> --- a/drivers/cxl/pmem.c
> +++ b/drivers/cxl/pmem.c
> @@ -52,7 +52,7 @@ static ssize_t id_show(struct device *dev, struct device_attribute *attr, char *
>  	struct cxl_nvdimm *cxl_nvd = nvdimm_provider_data(nvdimm);
>  	struct cxl_dev_state *cxlds = cxl_nvd->cxlmd->cxlds;
>  
> -	return sysfs_emit(buf, "%lld\n", cxlds->serial);
> +	return sysfs_emit(buf, "%llu\n", cxlds->serial);
>  }
>  static DEVICE_ATTR_RO(id);
>  
> -- 
> 2.37.3
> 
>