Re: [PATCH v4 15/21] cxl/pmem: Translate NVDIMM label commands to CXL label commands

[Ben Widawsky <ben.widawsky@intel.com>]

On 21-09-08 22:12:54, Dan Williams wrote:
> 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.
> 
> Acked-by: Ben Widawsky <ben.widawsky@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/cxl/pmem.c |  125 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 121 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
> index a972af7a6e0b..29d24f13aa73 100644
> --- a/drivers/cxl/pmem.c
> +++ b/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>
> @@ -48,10 +49,10 @@ 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;
>  	struct nvdimm *nvdimm = NULL;
> -	unsigned long flags = 0;
>  	int rc = -ENXIO;
>  
>  	cxl_nvb = cxl_find_nvdimm_bridge();
> @@ -66,8 +67,11 @@ static int cxl_nvdimm_probe(struct device *dev)
>  
>  	set_bit(NDD_LABELING, &flags);
>  	rc = -ENOMEM;
> -	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);
>  	dev_set_drvdata(dev, nvdimm);
>  
>  out_unlock:
> @@ -89,11 +93,124 @@ 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, int *cmd_rc)
> +{
> +	if (sizeof(*cmd) > buf_len)
> +		return -EINVAL;
> +
> +	*cmd = (struct nd_cmd_get_config_size) {
> +		 .config_size = cxlm->lsa_size,
> +		 .max_xfer = cxlm->payload_size,
> +	};
> +	*cmd_rc = 0;
> +
> +	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, int *cmd_rc)
> +{
> +	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;
> +	*cmd_rc = 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, int *cmd_rc)
> +{
> +	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]);
> +	*cmd_rc = 0;
> +	kvfree(set_lsa);
> +
> +	return rc;
> +}
> +
> +static int cxl_pmem_nvdimm_ctl(struct nvdimm *nvdimm, unsigned int cmd,
> +			       void *buf, unsigned int buf_len, int *cmd_rc)
> +{
> +	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, cmd_rc);
> +	case ND_CMD_GET_CONFIG_DATA:
> +		return cxl_pmem_get_config_data(cxlm, buf, buf_len, cmd_rc);
> +	case ND_CMD_SET_CONFIG_DATA:
> +		return cxl_pmem_set_config_data(cxlm, buf, buf_len, cmd_rc);
> +	default:
> +		return -ENOTTY;
> +	}
> +}
> +

Is there some intended purpose for passing cmd_rc down, if it isn't actually
ever used? Perhaps add it when needed later?

>  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;
> +	if (!nvdimm)
> +		return -ENOTTY;
> +	return cxl_pmem_nvdimm_ctl(nvdimm, cmd, buf, buf_len, cmd_rc);
>  }
>  
>  static bool online_nvdimm_bus(struct cxl_nvdimm_bridge *cxl_nvb)
>