linux-kernel - Re: [PATCH V2 10/20] nvdimm/region_label: Preserve cxl region information from region label

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Message-ID: <20250813161151.00006d59@huawei.com>
Date: Wed, 13 Aug 2025 16:11:51 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Neeraj Kumar <s.neeraj@...sung.com>
CC: <linux-cxl@...r.kernel.org>, <nvdimm@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, <gost.dev@...sung.com>,
	<a.manzanares@...sung.com>, <vishak.g@...sung.com>, <neeraj.kernel@...il.com>
Subject: Re: [PATCH V2 10/20] nvdimm/region_label: Preserve cxl region
 information from region label

On Wed, 30 Jul 2025 17:41:59 +0530
Neeraj Kumar <s.neeraj@...sung.com> wrote:

> Preserve region information from region label during nvdimm_probe. This
> preserved region information is used for creating cxl region to achieve
> region persistency across reboot.
> 
> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>

See below.

> diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c
> index 064a945dcdd1..bcac05371f87 100644
> --- a/drivers/nvdimm/label.c
> +++ b/drivers/nvdimm/label.c
> @@ -473,6 +473,47 @@ int nd_label_reserve_dpa(struct nvdimm_drvdata *ndd)
>  	return 0;
>  }
>  
> +int nvdimm_cxl_region_preserve(struct nvdimm_drvdata *ndd)
> +{
> +	struct nvdimm *nvdimm = to_nvdimm(ndd->dev);
> +	struct cxl_pmem_region_params *params = &nvdimm->cxl_region_params;
> +	struct nd_namespace_index *nsindex;
> +	unsigned long *free;
> +	u32 nslot, slot;
> +
> +	if (!preamble_current(ndd, &nsindex, &free, &nslot))
> +		return 0; /* no label, nothing to preserve */
> +
> +	for_each_clear_bit_le(slot, free, nslot) {
> +		struct nd_lsa_label *nd_label;
> +		struct cxl_region_label *rg_label;
> +		uuid_t rg_type, region_type;
> +
> +		nd_label = to_label(ndd, slot);
> +		rg_label = &nd_label->rg_label;
> +		uuid_parse(CXL_REGION_UUID, &region_type);
> +		import_uuid(&rg_type, nd_label->rg_label.type);
> +
> +		/* REVISIT: Currently preserving only one region */

In practice, is this a significant issue or not?  I.e. should we not
merge this series until this has been revisited?

> +		if (uuid_equal(&region_type, &rg_type)) {
> +			nvdimm->is_region_label = true;
> +			import_uuid(&params->uuid, rg_label->uuid);
> +			params->flags = __le32_to_cpu(rg_label->flags);
> +			params->nlabel = __le16_to_cpu(rg_label->nlabel);
> +			params->position = __le16_to_cpu(rg_label->position);
> +			params->dpa = __le64_to_cpu(rg_label->dpa);
> +			params->rawsize = __le64_to_cpu(rg_label->rawsize);
> +			params->hpa = __le64_to_cpu(rg_label->hpa);
> +			params->slot = __le32_to_cpu(rg_label->slot);
> +			params->ig = __le32_to_cpu(rg_label->ig);
> +			params->align = __le32_to_cpu(rg_label->align);
> +			break;
> +		}
> +	}
> +
> +	return 0;
> +}