Re: [PATCH v12 3/8] cxl/cdat: Gather DSMAS data for DCD partitions

On Fri, Jul 31, 2026 at 01:48:08AM -0700, Anisa Su wrote:
> From: Ira Weiny <[email protected]>
> 
> 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 <[email protected]>
> Co-developed-by: Anisa Su <[email protected]>
> Signed-off-by: Anisa Su <[email protected]>
> Tested-by: Wonjae Lee <[email protected]>
> Tested-by: Junhee Park <[email protected]>
> Tested-by: Heesoo Kim <[email protected]>
> Reviewed-by: Dave Jiang <[email protected]>
> ---
>  drivers/cxl/core/cdat.c | 13 +++++++++++++
>  drivers/cxl/core/hdm.c  |  1 +
>  drivers/cxl/core/mbox.c | 22 ++++++++++++++++------
>  drivers/cxl/cxlmem.h    |  2 ++
>  include/cxl/cxl.h       |  4 ++++
>  5 files changed, 36 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
> index 5c9f07262513..37136b2cf7e4 100644
> --- a/drivers/cxl/core/cdat.c
> +++ b/drivers/cxl/core/cdat.c
> @@ -17,6 +17,7 @@ struct dsmas_entry {
>  	struct access_coordinate cdat_coord[ACCESS_COORDINATE_MAX];
>  	int entries;
>  	int qos_class;
> +	bool shareable;
>  };
>  
>  static u32 cdat_normalize(u16 entry, u64 base, u8 type)
> @@ -74,6 +75,7 @@ static int cdat_dsmas_handler(union acpi_subtable_headers *header, void *arg,
>  		return -ENOMEM;
>  
>  	dent->handle = dsmas->dsmad_handle;
> +	dent->shareable = dsmas->flags & ACPI_CDAT_DSMAS_SHAREABLE;
>  	dent->dpa_range.start = le64_to_cpu((__force __le64)dsmas->dpa_base_address);
>  	dent->dpa_range.end = le64_to_cpu((__force __le64)dsmas->dpa_base_address) +
>  			      le64_to_cpu((__force __le64)dsmas->dpa_length) - 1;
> @@ -266,15 +268,26 @@ static void cxl_memdev_set_qos_class(struct cxl_dev_state *cxlds,
>  		bool found = false;
>  
>  		for (int i = 0; i < cxlds->nr_partitions; i++) {
> +			enum cxl_partition_mode mode = cxlds->part[i].mode;
>  			struct resource *res = &cxlds->part[i].res;
> +			u8 handle = cxlds->part[i].handle;
>  			struct range range = {
>  				.start = res->start,
>  				.end = res->end,
>  			};
>  
>  			if (range_contains(&range, &dent->dpa_range)) {
> +				if (mode == CXL_PARTMODE_DYNAMIC_RAM_1 &&
> +				    dent->handle != handle) {
> +					dev_warn(dev,
> +						 "Dynamic RAM perf mismatch; %pra (%u) vs %pra (%u)\n",
> +						 &range, handle, &dent->dpa_range,
> +						 dent->handle);
> +					continue;

Seems like the above message needs to say that the DSMAD handle from
mbox disagrees w CDAT DSMAS handle. Those (%u) that are handles have
no description.
With the above mismatch and continue, the loop exits w found still
false. Is that really true?


> +				}
>  				update_perf_entry(dev, dent,
>  						  &cxlds->part[i].perf);
> +				cxlds->part[i].shareable = dent->shareable;


why is shareable assigned for every node, and not only DYNAMIC_RAM_1

>  				found = true;
>  				break;
>  			}

Above nesting can be improved. Inverting range_contains() to unindent
the main body. A 'part' local pointer would reduce repeated indexing.


> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index 0ef076c08ed2..7f63b86887f4 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -477,6 +477,7 @@ int cxl_dpa_setup(struct cxl_dev_state *cxlds, const struct cxl_dpa_info *info)
>  
>  		cxlds->part[i].perf.qos_class = CXL_QOS_CLASS_INVALID;
>  		cxlds->part[i].mode = part->mode;
> +		cxlds->part[i].handle = part->handle;
>  
>  		/* Require ordered + contiguous partitions */
>  		if (i) {
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index d79019fbd790..a6cdea9f4080 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -1357,10 +1357,16 @@ static int cxl_dc_check(struct device *dev, struct cxl_dc_partition_info *part_a
>  {
>  	u64 blk_size = le64_to_cpu(dev_part->block_size);
>  	u64 len = le64_to_cpu(dev_part->length);
> +	u32 handle = le32_to_cpu(dev_part->dsmad_handle);
>  
>  	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;
> +	if (handle & ~0xFF) {
> +		dev_warn(dev, "DSMAD handle 0x%x has non-zero reserved bits\n", handle);

I don't see reserve bits for a DSMAD handle. I think this check is valid
but the message has the wrong constraint. Expect it is a CDAT constraint.


> +		return -EINVAL;
> +	}
> +	part_array[index].handle = handle;
>  
>  	/* Check partitions are in increasing DPA order */
>  	if (index > 0) {
> @@ -1536,6 +1542,7 @@ 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 %llu size %llu\n",
>  		dc_info->start, dc_info->size);
>  
> @@ -1543,7 +1550,8 @@ int cxl_dev_dc_identify(struct cxl_mailbox *mbox,
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_dev_dc_identify, "CXL");
>  
> -static void add_part(struct cxl_dpa_info *info, u64 start, u64 size, enum cxl_partition_mode mode)
> +static void add_part(struct cxl_dpa_info *info, u64 start, u64 size,
> +		     enum cxl_partition_mode mode, u8 handle)
>  {
>  	int i = info->nr_partitions;
>  
> @@ -1555,6 +1563,7 @@ static void add_part(struct cxl_dpa_info *info, u64 start, u64 size, enum cxl_pa
>  		.end = start + size - 1,
>  	};
>  	info->part[i].mode = mode;
> +	info->part[i].handle = handle;
>  	info->nr_partitions++;
>  }
>  
> @@ -1572,9 +1581,9 @@ int cxl_mem_dpa_fetch(struct cxl_memdev_state *mds, struct cxl_dpa_info *info)
>  	info->size = mds->total_bytes;
>  
>  	if (mds->partition_align_bytes == 0) {
> -		add_part(info, 0, mds->volatile_only_bytes, CXL_PARTMODE_RAM);
> +		add_part(info, 0, mds->volatile_only_bytes, CXL_PARTMODE_RAM, 0);
>  		add_part(info, mds->volatile_only_bytes,
> -			 mds->persistent_only_bytes, CXL_PARTMODE_PMEM);
> +			 mds->persistent_only_bytes, CXL_PARTMODE_PMEM, 0);
>  		return 0;
>  	}
>  
> @@ -1584,9 +1593,9 @@ int cxl_mem_dpa_fetch(struct cxl_memdev_state *mds, struct cxl_dpa_info *info)
>  		return rc;
>  	}
>  
> -	add_part(info, 0, mds->active_volatile_bytes, CXL_PARTMODE_RAM);
> +	add_part(info, 0, mds->active_volatile_bytes, CXL_PARTMODE_RAM, 0);
>  	add_part(info, mds->active_volatile_bytes, mds->active_persistent_bytes,
> -		 CXL_PARTMODE_PMEM);
> +		 CXL_PARTMODE_PMEM, 0);
>  
>  	return 0;
>  }
> @@ -1638,7 +1647,8 @@ void cxl_configure_dcd(struct cxl_memdev_state *mds, struct cxl_dpa_info *info)
>  	info->size += dc_info.size;
>  	dev_dbg(dev, "Adding dynamic ram partition 1; %llu size %llu\n",
>  		dc_info.start, dc_info.size);
> -	add_part(info, dc_info.start, dc_info.size, CXL_PARTMODE_DYNAMIC_RAM_1);
> +	add_part(info, dc_info.start, dc_info.size, CXL_PARTMODE_DYNAMIC_RAM_1,
> +		 dc_info.handle);
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_configure_dcd, "CXL");
>  
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index a9782939d82b..eb1e6f7a2038 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -140,6 +140,7 @@ 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;
>  };
> @@ -853,6 +854,7 @@ int cxl_dev_state_identify(struct cxl_memdev_state *mds);
>  struct cxl_dc_partition_info {
>  	u64 start;
>  	u64 size;
> +	u8 handle;
>  };
>  
>  int cxl_dev_dc_identify(struct cxl_mailbox *mbox,
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index 87c2bd73df21..baf0132c70a3 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -141,11 +141,15 @@ enum cxl_partition_mode {
>   * @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: DSMAS handle intended to represent this partition

What is with the 'intended'? Either it represents the partition
or the match failed.


> + * @shareable: Is the partition sharable (from its CDAT DSMAS entry)
                                   ^
				   shareable


>   */
>  struct cxl_dpa_partition {
>  	struct resource res;
>  	struct cxl_dpa_perf perf;
>  	enum cxl_partition_mode mode;
> +	u8 handle;
> +	bool shareable;
>  };
>  
>  #define CXL_NR_PARTITIONS_MAX 3
> -- 
> 2.43.0
>