cxl/pmem: Add "Set Passphrase" security command support

Create callback function to support the nvdimm_security_ops ->change_key()
callback. Translate the operation to send "Set Passphrase" security command
for CXL memory device. The operation supports setting a passphrase for the
CXL persistent memory device. It also supports the changing of the
currently set passphrase. The operation allows manipulation of a user
passphrase or a master passphrase.

See CXL rev3.0 spec section 8.2.9.8.6.2 for reference.

However, the spec leaves a gap WRT master passphrase usages. The spec does
not define any ways to retrieve the status of if the support of master
passphrase is available for the device, nor does the commands that utilize
master passphrase will return a specific error that indicates master
passphrase is not supported. If using a device does not support master
passphrase and a command is issued with a master passphrase, the error
message returned by the device will be ambiguous.
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/166983610751.2734609.4445075071552032091.stgit@djiang5-desk3.ch.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/core/mbox.c

@@ -66,6 +66,7 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
 	CXL_CMD(SCAN_MEDIA, 0x11, 0, 0),
 	CXL_CMD(GET_SCAN_MEDIA, 0, CXL_VARIABLE_PAYLOAD, 0),
 	CXL_CMD(GET_SECURITY_STATE, 0, 0x4, 0),
+	CXL_CMD(SET_PASSPHRASE, 0x60, 0, 0),
 };
 
 /*

drivers/cxl/cxlmem.h

@@ -274,6 +274,7 @@ enum cxl_opcode {
 	CXL_MBOX_OP_SCAN_MEDIA		= 0x4304,
 	CXL_MBOX_OP_GET_SCAN_MEDIA	= 0x4305,
 	CXL_MBOX_OP_GET_SECURITY_STATE	= 0x4500,
+	CXL_MBOX_OP_SET_PASSPHRASE	= 0x4501,
 	CXL_MBOX_OP_MAX			= 0x10000
 };
 
@@ -380,6 +381,20 @@ struct cxl_mem_command {
 #define CXL_PMEM_SEC_STATE_USER_PLIMIT		0x10
 #define CXL_PMEM_SEC_STATE_MASTER_PLIMIT	0x20
 
+/* set passphrase input payload */
+struct cxl_set_pass {
+	u8 type;
+	u8 reserved[31];
+	/* CXL field using NVDIMM define, same length */
+	u8 old_pass[NVDIMM_PASSPHRASE_LEN];
+	u8 new_pass[NVDIMM_PASSPHRASE_LEN];
+} __packed;
+
+enum {
+	CXL_PMEM_SEC_PASS_MASTER = 0,
+	CXL_PMEM_SEC_PASS_USER,
+};
+
 int cxl_mbox_send_cmd(struct cxl_dev_state *cxlds, u16 opcode, void *in,
 		      size_t in_size, void *out, size_t out_size);
 int cxl_dev_state_identify(struct cxl_dev_state *cxlds);

drivers/cxl/security.c

@@ -49,8 +49,30 @@ static unsigned long cxl_pmem_get_security_flags(struct nvdimm *nvdimm,
 	return security_flags;
 }
 
+static int cxl_pmem_security_change_key(struct nvdimm *nvdimm,
+					const struct nvdimm_key_data *old_data,
+					const struct nvdimm_key_data *new_data,
+					enum nvdimm_passphrase_type ptype)
+{
+	struct cxl_nvdimm *cxl_nvd = nvdimm_provider_data(nvdimm);
+	struct cxl_memdev *cxlmd = cxl_nvd->cxlmd;
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	struct cxl_set_pass set_pass;
+	int rc;
+
+	set_pass.type = ptype == NVDIMM_MASTER ?
+		CXL_PMEM_SEC_PASS_MASTER : CXL_PMEM_SEC_PASS_USER;
+	memcpy(set_pass.old_pass, old_data->data, NVDIMM_PASSPHRASE_LEN);
+	memcpy(set_pass.new_pass, new_data->data, NVDIMM_PASSPHRASE_LEN);
+
+	rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_SET_PASSPHRASE,
+			       &set_pass, sizeof(set_pass), NULL, 0);
+	return rc;
+}
+
 static const struct nvdimm_security_ops __cxl_security_ops = {
 	.get_flags = cxl_pmem_get_security_flags,
+	.change_key = cxl_pmem_security_change_key,
 };
 
 const struct nvdimm_security_ops *cxl_security_ops = &__cxl_security_ops;

include/uapi/linux/cxl_mem.h

@@ -42,6 +42,7 @@
 	___C(SCAN_MEDIA, "Scan Media"),                                   \
 	___C(GET_SCAN_MEDIA, "Get Scan Media Results"),                   \
 	___C(GET_SECURITY_STATE, "Get Security State"),			  \
+	___C(SET_PASSPHRASE, "Set Passphrase"),				  \
 	___C(MAX, "invalid / last command")
 
 #define ___C(a, b) CXL_MEM_COMMAND_ID_##a