cxl/pmem: Add Disable Passphrase security command support

Create callback function to support the nvdimm_security_ops ->disable()
callback. Translate the operation to send "Disable Passphrase" security
command for CXL memory device. The operation supports disabling a
passphrase for the CXL persistent memory device. In the original
implementation of nvdimm_security_ops, this operation only supports
disabling of the user passphrase. This is due to the NFIT version of
disable passphrase only supported disabling of user passphrase. The CXL
spec allows disabling of the master passphrase as well which
nvidmm_security_ops does not support yet. In this commit, the callback
function will only support user passphrase.

See CXL rev3.0 spec section 8.2.9.8.6.3 for reference.
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/166983611878.2734609.10602135274526390127.stgit@djiang5-desk3.ch.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/core/mbox.c

@@ -67,6 +67,7 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
 	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),
+	CXL_CMD(DISABLE_PASSPHRASE, 0x40, 0, 0),
 };
 
 /*

drivers/cxl/cxlmem.h

@@ -275,6 +275,7 @@ enum cxl_opcode {
 	CXL_MBOX_OP_GET_SCAN_MEDIA	= 0x4305,
 	CXL_MBOX_OP_GET_SECURITY_STATE	= 0x4500,
 	CXL_MBOX_OP_SET_PASSPHRASE	= 0x4501,
+	CXL_MBOX_OP_DISABLE_PASSPHRASE	= 0x4502,
 	CXL_MBOX_OP_MAX			= 0x10000
 };
 
@@ -390,6 +391,13 @@ struct cxl_set_pass {
 	u8 new_pass[NVDIMM_PASSPHRASE_LEN];
 } __packed;
 
+/* disable passphrase input payload */
+struct cxl_disable_pass {
+	u8 type;
+	u8 reserved[31];
+	u8 pass[NVDIMM_PASSPHRASE_LEN];
+} __packed;
+
 enum {
 	CXL_PMEM_SEC_PASS_MASTER = 0,
 	CXL_PMEM_SEC_PASS_USER,

drivers/cxl/security.c

@@ -70,9 +70,27 @@ static int cxl_pmem_security_change_key(struct nvdimm *nvdimm,
 	return rc;
 }
 
+static int cxl_pmem_security_disable(struct nvdimm *nvdimm,
+				     const struct nvdimm_key_data *key_data)
+{
+	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_disable_pass dis_pass;
+	int rc;
+
+	dis_pass.type = CXL_PMEM_SEC_PASS_USER;
+	memcpy(dis_pass.pass, key_data->data, NVDIMM_PASSPHRASE_LEN);
+
+	rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_DISABLE_PASSPHRASE,
+			       &dis_pass, sizeof(dis_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,
+	.disable = cxl_pmem_security_disable,
 };
 
 const struct nvdimm_security_ops *cxl_security_ops = &__cxl_security_ops;

include/uapi/linux/cxl_mem.h

@@ -43,6 +43,7 @@
 	___C(GET_SCAN_MEDIA, "Get Scan Media Results"),                   \
 	___C(GET_SECURITY_STATE, "Get Security State"),			  \
 	___C(SET_PASSPHRASE, "Set Passphrase"),				  \
+	___C(DISABLE_PASSPHRASE, "Disable Passphrase"),			  \
 	___C(MAX, "invalid / last command")
 
 #define ___C(a, b) CXL_MEM_COMMAND_ID_##a