linux-kernel - Re: [RFC PATCH 01/20] nvdimm/label: Introduce NDD_CXL

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Message-ID: <686574227268c_30f2b7294f@iweiny-mobl.notmuch>
Date: Wed, 2 Jul 2025 13:02:10 -0500
From: Ira Weiny <ira.weiny@...el.com>
To: Neeraj Kumar <s.neeraj@...sung.com>, <dan.j.williams@...el.com>,
	<dave@...olabs.net>, <jonathan.cameron@...wei.com>, <dave.jiang@...el.com>,
	<alison.schofield@...el.com>, <vishal.l.verma@...el.com>,
	<ira.weiny@...el.com>
CC: <a.manzanares@...sung.com>, <nifan.cxl@...il.com>, <anisa.su@...sung.com>,
	<vishak.g@...sung.com>, <krish.reddy@...sung.com>, <arun.george@...sung.com>,
	<alok.rathore@...sung.com>, <s.neeraj@...sung.com>,
	<neeraj.kernel@...il.com>, <linux-kernel@...r.kernel.org>,
	<linux-cxl@...r.kernel.org>, <nvdimm@...ts.linux.dev>,
	<gost.dev@...sung.com>, <cpgs@...sung.com>
Subject: Re: [RFC PATCH 01/20] nvdimm/label: Introduce NDD_CXL_LABEL flag to
 set cxl label format

Neeraj Kumar wrote:
> NDD_CXL_LABEL is introduced to set cxl LSA 2.1 label format
> Accordingly updated label index version

I'm not following why CXL specific code needs to be in nvdimm?

I did not get a cover letter in this thread and looking at lore I don't
see one either:

https://lore.kernel.org/all/158453976.61750165203630.JavaMail.epsvc@epcpadp1new/

So perhaps I am completely out of the loop here?  Could you point me at a
cover letter?

Ira

> 
> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>
> ---
>  drivers/nvdimm/dimm.c      |  1 +
>  drivers/nvdimm/dimm_devs.c | 10 ++++++++++
>  drivers/nvdimm/label.c     | 16 ++++++++++++----
>  drivers/nvdimm/nd.h        |  1 +
>  include/linux/libnvdimm.h  |  3 +++
>  5 files changed, 27 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/nvdimm/dimm.c b/drivers/nvdimm/dimm.c
> index 91d9163ee303..8753b5cd91cc 100644
> --- a/drivers/nvdimm/dimm.c
> +++ b/drivers/nvdimm/dimm.c
> @@ -62,6 +62,7 @@ static int nvdimm_probe(struct device *dev)
>  	if (rc < 0)
>  		dev_dbg(dev, "failed to unlock dimm: %d\n", rc);
>  
> +	ndd->cxl = nvdimm_check_cxl_label_format(ndd->dev);
>  
>  	/*
>  	 * EACCES failures reading the namespace label-area-properties
> diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
> index 21498d461fde..e8f545f889fd 100644
> --- a/drivers/nvdimm/dimm_devs.c
> +++ b/drivers/nvdimm/dimm_devs.c
> @@ -18,6 +18,16 @@
>  
>  static DEFINE_IDA(dimm_ida);
>  
> +bool nvdimm_check_cxl_label_format(struct device *dev)
> +{
> +	struct nvdimm *nvdimm = to_nvdimm(dev);
> +
> +	if (test_bit(NDD_CXL_LABEL, &nvdimm->flags))
> +		return true;
> +
> +	return false;
> +}
> +
>  /*
>   * Retrieve bus and dimm handle and return if this bus supports
>   * get_config_data commands
> diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c
> index 082253a3a956..48b5ba90216d 100644
> --- a/drivers/nvdimm/label.c
> +++ b/drivers/nvdimm/label.c
> @@ -687,11 +687,19 @@ static int nd_label_write_index(struct nvdimm_drvdata *ndd, int index, u32 seq,
>  		- (unsigned long) to_namespace_index(ndd, 0);
>  	nsindex->labeloff = __cpu_to_le64(offset);
>  	nsindex->nslot = __cpu_to_le32(nslot);
> -	nsindex->major = __cpu_to_le16(1);
> -	if (sizeof_namespace_label(ndd) < 256)
> +
> +	/* Support CXL LSA 2.1 label format */
> +	if (ndd->cxl) {
> +		nsindex->major = __cpu_to_le16(2);
>  		nsindex->minor = __cpu_to_le16(1);
> -	else
> -		nsindex->minor = __cpu_to_le16(2);
> +	} else {
> +		nsindex->major = __cpu_to_le16(1);
> +		if (sizeof_namespace_label(ndd) < 256)
> +			nsindex->minor = __cpu_to_le16(1);
> +		else
> +			nsindex->minor = __cpu_to_le16(2);
> +	}
> +
>  	nsindex->checksum = __cpu_to_le64(0);
>  	if (flags & ND_NSINDEX_INIT) {
>  		unsigned long *free = (unsigned long *) nsindex->free;
> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
> index 5ca06e9a2d29..304f0e9904f1 100644
> --- a/drivers/nvdimm/nd.h
> +++ b/drivers/nvdimm/nd.h
> @@ -522,6 +522,7 @@ void nvdimm_set_labeling(struct device *dev);
>  void nvdimm_set_locked(struct device *dev);
>  void nvdimm_clear_locked(struct device *dev);
>  int nvdimm_security_setup_events(struct device *dev);
> +bool nvdimm_check_cxl_label_format(struct device *dev);
>  #if IS_ENABLED(CONFIG_NVDIMM_KEYS)
>  int nvdimm_security_unlock(struct device *dev);
>  #else
> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
> index e772aae71843..0a55900842c8 100644
> --- a/include/linux/libnvdimm.h
> +++ b/include/linux/libnvdimm.h
> @@ -44,6 +44,9 @@ enum {
>  	/* dimm provider wants synchronous registration by __nvdimm_create() */
>  	NDD_REGISTER_SYNC = 8,
>  
> +	/* dimm supports region labels (LSA Format 2.1) */
> +	NDD_CXL_LABEL = 9,
> +
>  	/* need to set a limit somewhere, but yes, this is likely overkill */
>  	ND_IOCTL_MAX_BUFLEN = SZ_4M,
>  	ND_CMD_MAX_ELEM = 5,
> -- 
> 2.34.1
> 
>