Re: [PATCH v3 21/28] cxl/pmem: Translate NVDIMM label commands to CXL label commands

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Tue, 24 Aug 2021 09:07:18 -0700
Dan Williams <dan.j.williams@intel.com> 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>
Minor query inline.

> ---
>  drivers/cxl/pmem.c |  121 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 117 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
> index 469b984176a2..6cc76302c8f8 100644
> --- a/drivers/cxl/pmem.c
> +++ b/drivers/cxl/pmem.c
> @@ -52,10 +52,10 @@ static int cxl_nvdimm_probe(struct device *dev)

> +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 */
> +	*(u32 *) &cmd->in_buf[cmd->in_length] = 0;

Are we guaranteed this is aligned? Not 'locally' obvious so maybe a comment?

> +	*cmd_rc = 0;
> +	kvfree(set_lsa);
> +
> +	return rc;
> +}
> +