Re: [PATCH v2 3/5] cxl: Introduce 'struct cxl_dpa_partition' and 'struct cxl_range_info'

[Ira Weiny <ira.weiny@intel.com>]

Dan Williams wrote:

[snip]

> +/* if this fails the caller must destroy @cxlds, there is no recovery */
> +int cxl_dpa_setup(struct cxl_dev_state *cxlds, const struct cxl_dpa_info *info)
> +{
> +	struct device *dev = cxlds->dev;
> +
> +	guard(rwsem_write)(&cxl_dpa_rwsem);
> +
> +	if (cxlds->nr_partitions)
> +		return -EBUSY;
> +
> +	if (!info->size || !info->nr_partitions) {
> +		cxlds->dpa_res = DEFINE_RES_MEM(0, 0);
> +		cxlds->nr_partitions = 0;
> +		return 0;
> +	}
> +
> +	cxlds->dpa_res = DEFINE_RES_MEM(0, info->size);
> +
> +	for (int i = 0; i < info->nr_partitions; i++) {
> +		const struct cxl_dpa_part_info *part = &info->part[i];
> +		const char *desc;
> +		int rc;
> +
> +		if (part->mode == CXL_PARTMODE_RAM)
> +			desc = "ram";
> +		else if (part->mode == CXL_PARTMODE_PMEM)
> +			desc = "pmem";
> +		else
> +			desc = "";

This can be a follow on patch but why not allow devices to name their
partitions?

> +		cxlds->part[i].perf.qos_class = CXL_QOS_CLASS_INVALID;
> +		cxlds->part[i].mode = part->mode;
> +		rc = add_dpa_res(dev, &cxlds->dpa_res, &cxlds->part[i].res,
> +				 part->range.start, range_len(&part->range),
> +				 desc);
> +		if (rc)
> +			return rc;
> +		cxlds->nr_partitions++;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(cxl_dpa_setup);
> +
>  int devm_cxl_dpa_reserve(struct cxl_endpoint_decoder *cxled,
>  				resource_size_t base, resource_size_t len,
>  				resource_size_t skipped)

[snip]

>  
> -static inline struct resource *to_ram_res(struct cxl_dev_state *cxlds)
> +
> +/* Static RAM is only expected at partition 0. */

Is this because the spec requires RAM first and the partition array must
remain in DPA order?

This could be in a follow on patch, but unless I'm missing something the
partition information must be specified in increasing DPA order.  Perhaps
that is accounted for in this series later.

Regardless for this patch I don't see any brokeness.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>