linux-kernel - Re: [PATCH v9 03/19] cxl/cdat: Gather DSMAS data for DCD partitions

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Message-ID: <20250414162914.00006bb7@huawei.com>
Date: Mon, 14 Apr 2025 16:29:14 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Ira Weiny <ira.weiny@...el.com>
CC: Dave Jiang <dave.jiang@...el.com>, Fan Ni <fan.ni@...sung.com>, "Dan
 Williams" <dan.j.williams@...el.com>, Davidlohr Bueso <dave@...olabs.net>,
	Alison Schofield <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, <linux-cxl@...r.kernel.org>,
	<nvdimm@...ts.linux.dev>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 03/19] cxl/cdat: Gather DSMAS data for DCD partitions

On Sun, 13 Apr 2025 17:52:11 -0500
Ira Weiny <ira.weiny@...el.com> wrote:

> Additional DCD partition (AKA region) information is contained in the
> DSMAS CDAT tables, including performance, read only, and shareable
> attributes.
> 
> Match DCD partitions with DSMAS tables and store the meta data.
> 
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>

> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index 866a423d6125..c589d8a330bb 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -1321,6 +1321,7 @@ static int cxl_dc_check(struct device *dev, struct cxl_dc_partition_info *part_a
>  	part_array[index].start = le64_to_cpu(dev_part->base);
>  	part_array[index].size = le64_to_cpu(dev_part->decode_length);
>  	part_array[index].size *= CXL_CAPACITY_MULTIPLIER;
> +	part_array[index].handle = le32_to_cpu(dev_part->dsmad_handle) & 0xFF;

Perhaps a comment on this.  Or a check that it is representable in
CDAT (where we only have the one byte) and a print + fail to carry on if not?

>  	len = le64_to_cpu(dev_part->length);
>  	blk_size = le64_to_cpu(dev_part->block_size);
>  
> @@ -1453,6 +1454,7 @@ int cxl_dev_dc_identify(struct cxl_mailbox *mbox,
>  	/* Return 1st partition */
>  	dc_info->start = partitions[0].start;
>  	dc_info->size = partitions[0].size;
> +	dc_info->handle = partitions[0].handle;
>  	dev_dbg(dev, "Returning partition 0 %zu size %zu\n",
>  		dc_info->start, dc_info->size);
>  
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 057933128d2c..96d8edaa5003 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -104,6 +104,7 @@ struct cxl_dpa_info {
>  	struct cxl_dpa_part_info {
>  		struct range range;
>  		enum cxl_partition_mode mode;
> +		u8 handle;
>  	} part[CXL_NR_PARTITIONS_MAX];
>  	int nr_partitions;
>  };
> @@ -387,12 +388,14 @@ enum cxl_devtype {
>   * @coord: QoS performance data (i.e. latency, bandwidth)
>   * @cdat_coord: raw QoS performance data from CDAT
>   * @qos_class: QoS Class cookies
> + * @shareable: Is the range sharable
>   */
>  struct cxl_dpa_perf {
>  	struct range dpa_range;
>  	struct access_coordinate coord[ACCESS_COORDINATE_MAX];
>  	struct access_coordinate cdat_coord[ACCESS_COORDINATE_MAX];
>  	int qos_class;
> +	bool shareable;

It feels a bit odd to have this in the dpa_perf structure as not really
a performance thing but I guess this is only convenient place to stash it.

>  };
>  
>  /**
> @@ -400,11 +403,13 @@ struct cxl_dpa_perf {
>   * @res: shortcut to the partition in the DPA resource tree (cxlds->dpa_res)
>   * @perf: performance attributes of the partition from CDAT
>   * @mode: operation mode for the DPA capacity, e.g. ram, pmem, dynamic...
> + * @handle: DMASS handle intended to represent this partition

DSMAS ?


>   */
>  struct cxl_dpa_partition {
>  	struct resource res;
>  	struct cxl_dpa_perf perf;
>  	enum cxl_partition_mode mode;
> +	u8 handle;
>  };
>  
>  /**
> @@ -881,6 +886,7 @@ struct cxl_mem_dev_info {
>  struct cxl_dc_partition_info {
>  	size_t start;
>  	size_t size;
> +	u8 handle;
>  };
>  
>  int cxl_dev_dc_identify(struct cxl_mailbox *mbox,
>