cxl/pmem: Translate NVDIMM label commands to CXL label commands

The LIBNVDIMM IOCTL UAPI calls back to the nvdimm-bus-provider to
translate the Linux command payload to the device native command format.
The LIBNVDIMM commands get-config-size, get-config-data, and
set-config-data, map to the CXL memory device commands device-identify,
get-lsa, and set-lsa. Recall that the label-storage-area (LSA) on an
NVDIMM device arranges for the provisioning of namespaces. Additionally
for CXL the LSA is used for provisioning regions as well.

The data from device-identify is already cached in the 'struct cxl_mem'
instance associated with @cxl_nvd, so that payload return is simply
crafted and no CXL command is issued. The conversion for get-lsa is
straightforward, but the conversion for set-lsa requires an allocation
to append the set-lsa header in front of the payload.

Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163122524923.2534512.9431316965424264864.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/pmem.c

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright(c) 2021 Intel Corporation. All rights reserved. */
 #include <linux/libnvdimm.h>
+#include <asm/unaligned.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/ndctl.h>
@@ -47,9 +48,9 @@ static int cxl_nvdimm_probe(struct device *dev)
 {
 	struct cxl_nvdimm *cxl_nvd = to_cxl_nvdimm(dev);
 	struct cxl_memdev *cxlmd = cxl_nvd->cxlmd;
+	unsigned long flags = 0, cmd_mask = 0;
 	struct cxl_mem *cxlm = cxlmd->cxlm;
 	struct cxl_nvdimm_bridge *cxl_nvb;
-	unsigned long flags = 0;
 	struct nvdimm *nvdimm;
 	int rc;
 
@@ -69,8 +70,11 @@ static int cxl_nvdimm_probe(struct device *dev)
 		goto out;
 
 	set_bit(NDD_LABELING, &flags);
-	nvdimm = nvdimm_create(cxl_nvb->nvdimm_bus, cxl_nvd, NULL, flags, 0, 0,
-			       NULL);
+	set_bit(ND_CMD_GET_CONFIG_SIZE, &cmd_mask);
+	set_bit(ND_CMD_GET_CONFIG_DATA, &cmd_mask);
+	set_bit(ND_CMD_SET_CONFIG_DATA, &cmd_mask);
+	nvdimm = nvdimm_create(cxl_nvb->nvdimm_bus, cxl_nvd, NULL, flags,
+			       cmd_mask, 0, NULL);
 	if (!nvdimm) {
 		rc = -ENOMEM;
 		goto out;
@@ -91,11 +95,127 @@ static struct cxl_driver cxl_nvdimm_driver = {
 	.id = CXL_DEVICE_NVDIMM,
 };
 
+static int cxl_pmem_get_config_size(struct cxl_mem *cxlm,
+				    struct nd_cmd_get_config_size *cmd,
+				    unsigned int buf_len)
+{
+	if (sizeof(*cmd) > buf_len)
+		return -EINVAL;
+
+	*cmd = (struct nd_cmd_get_config_size) {
+		 .config_size = cxlm->lsa_size,
+		 .max_xfer = cxlm->payload_size,
+	};
+
+	return 0;
+}
+
+static int cxl_pmem_get_config_data(struct cxl_mem *cxlm,
+				    struct nd_cmd_get_config_data_hdr *cmd,
+				    unsigned int buf_len)
+{
+	struct cxl_mbox_get_lsa {
+		u32 offset;
+		u32 length;
+	} get_lsa;
+	int rc;
+
+	if (sizeof(*cmd) > buf_len)
+		return -EINVAL;
+	if (struct_size(cmd, out_buf, cmd->in_length) > buf_len)
+		return -EINVAL;
+
+	get_lsa = (struct cxl_mbox_get_lsa) {
+		.offset = cmd->in_offset,
+		.length = cmd->in_length,
+	};
+
+	rc = cxl_mem_mbox_send_cmd(cxlm, CXL_MBOX_OP_GET_LSA, &get_lsa,
+				   sizeof(get_lsa), cmd->out_buf,
+				   cmd->in_length);
+	cmd->status = 0;
+
+	return rc;
+}
+
+static int cxl_pmem_set_config_data(struct cxl_mem *cxlm,
+				    struct nd_cmd_set_config_hdr *cmd,
+				    unsigned int buf_len)
+{
+	struct cxl_mbox_set_lsa {
+		u32 offset;
+		u32 reserved;
+		u8 data[];
+	} *set_lsa;
+	int rc;
+
+	if (sizeof(*cmd) > buf_len)
+		return -EINVAL;
+
+	/* 4-byte status follows the input data in the payload */
+	if (struct_size(cmd, in_buf, cmd->in_length) + 4 > buf_len)
+		return -EINVAL;
+
+	set_lsa =
+		kvzalloc(struct_size(set_lsa, data, cmd->in_length), GFP_KERNEL);
+	if (!set_lsa)
+		return -ENOMEM;
+
+	*set_lsa = (struct cxl_mbox_set_lsa) {
+		.offset = cmd->in_offset,
+	};
+	memcpy(set_lsa->data, cmd->in_buf, cmd->in_length);
+
+	rc = cxl_mem_mbox_send_cmd(cxlm, CXL_MBOX_OP_SET_LSA, set_lsa,
+				   struct_size(set_lsa, data, cmd->in_length),
+				   NULL, 0);
+
+	/*
+	 * Set "firmware" status (4-packed bytes at the end of the input
+	 * payload.
+	 */
+	put_unaligned(0, (u32 *) &cmd->in_buf[cmd->in_length]);
+	kvfree(set_lsa);
+
+	return rc;
+}
+
+static int cxl_pmem_nvdimm_ctl(struct nvdimm *nvdimm, unsigned int cmd,
+			       void *buf, unsigned int buf_len)
+{
+	struct cxl_nvdimm *cxl_nvd = nvdimm_provider_data(nvdimm);
+	unsigned long cmd_mask = nvdimm_cmd_mask(nvdimm);
+	struct cxl_memdev *cxlmd = cxl_nvd->cxlmd;
+	struct cxl_mem *cxlm = cxlmd->cxlm;
+
+	if (!test_bit(cmd, &cmd_mask))
+		return -ENOTTY;
+
+	switch (cmd) {
+	case ND_CMD_GET_CONFIG_SIZE:
+		return cxl_pmem_get_config_size(cxlm, buf, buf_len);
+	case ND_CMD_GET_CONFIG_DATA:
+		return cxl_pmem_get_config_data(cxlm, buf, buf_len);
+	case ND_CMD_SET_CONFIG_DATA:
+		return cxl_pmem_set_config_data(cxlm, buf, buf_len);
+	default:
+		return -ENOTTY;
+	}
+}
+
 static int cxl_pmem_ctl(struct nvdimm_bus_descriptor *nd_desc,
 			struct nvdimm *nvdimm, unsigned int cmd, void *buf,
 			unsigned int buf_len, int *cmd_rc)
 {
-	return -ENOTTY;
+	/*
+	 * No firmware response to translate, let the transport error
+	 * code take precedence.
+	 */
+	*cmd_rc = 0;
+
+	if (!nvdimm)
+		return -ENOTTY;
+	return cxl_pmem_nvdimm_ctl(nvdimm, cmd, buf, buf_len);
 }
 
 static bool online_nvdimm_bus(struct cxl_nvdimm_bridge *cxl_nvb)