Re: [PATCH v18 05/20] cxl: Support dpa initialization without a mailbox

[Dave Jiang <dave.jiang@intel.com>]

On 9/18/25 2:17 AM, alejandro.lucero-palau@amd.com wrote:
> From: Alejandro Lucero <alucerop@amd.com>
> 
> Type3 relies on mailbox CXL_MBOX_OP_IDENTIFY command for initializing
> memdev state params which end up being used for DPA initialization.
> 
> Allow a Type2 driver to initialize DPA simply by giving the size of its
> volatile hardware partition.
> 
> Move related functions to memdev.
> 
> Add sfc driver as the client.
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/cxl/core/core.h            |  2 +
>  drivers/cxl/core/mbox.c            | 51 +----------------------
>  drivers/cxl/core/memdev.c          | 66 ++++++++++++++++++++++++++++++
>  drivers/net/ethernet/sfc/efx_cxl.c |  4 ++
>  include/cxl/cxl.h                  |  1 +
>  5 files changed, 74 insertions(+), 50 deletions(-)
> 
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index d96213c02fd6..c4dddbec5d6e 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -90,6 +90,8 @@ void __iomem *devm_cxl_iomap_block(struct device *dev, resource_size_t addr,
>  struct dentry *cxl_debugfs_create_dir(const char *dir);
>  int cxl_dpa_set_part(struct cxl_endpoint_decoder *cxled,
>  		     enum cxl_partition_mode mode);
> +struct cxl_memdev_state;
> +int cxl_mem_get_partition_info(struct cxl_memdev_state *mds);
>  int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, u64 size);
>  int cxl_dpa_free(struct cxl_endpoint_decoder *cxled);
>  resource_size_t cxl_dpa_size(struct cxl_endpoint_decoder *cxled);
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index bee84d0101d1..d57a0c2d39fb 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -1144,7 +1144,7 @@ EXPORT_SYMBOL_NS_GPL(cxl_mem_get_event_records, "CXL");
>   *
>   * See CXL @8.2.9.5.2.1 Get Partition Info
>   */
> -static int cxl_mem_get_partition_info(struct cxl_memdev_state *mds)
> +int cxl_mem_get_partition_info(struct cxl_memdev_state *mds)
>  {
>  	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
>  	struct cxl_mbox_get_partition_info pi;
> @@ -1300,55 +1300,6 @@ int cxl_mem_sanitize(struct cxl_memdev *cxlmd, u16 cmd)
>  	return -EBUSY;
>  }
>  
> -static void add_part(struct cxl_dpa_info *info, u64 start, u64 size, enum cxl_partition_mode mode)
> -{
> -	int i = info->nr_partitions;
> -
> -	if (size == 0)
> -		return;
> -
> -	info->part[i].range = (struct range) {
> -		.start = start,
> -		.end = start + size - 1,
> -	};
> -	info->part[i].mode = mode;
> -	info->nr_partitions++;
> -}
> -
> -int cxl_mem_dpa_fetch(struct cxl_memdev_state *mds, struct cxl_dpa_info *info)
> -{
> -	struct cxl_dev_state *cxlds = &mds->cxlds;
> -	struct device *dev = cxlds->dev;
> -	int rc;
> -
> -	if (!cxlds->media_ready) {
> -		info->size = 0;
> -		return 0;
> -	}
> -
> -	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, mds->volatile_only_bytes,
> -			 mds->persistent_only_bytes, CXL_PARTMODE_PMEM);
> -		return 0;
> -	}
> -
> -	rc = cxl_mem_get_partition_info(mds);
> -	if (rc) {
> -		dev_err(dev, "Failed to query partition information\n");
> -		return rc;
> -	}
> -
> -	add_part(info, 0, mds->active_volatile_bytes, CXL_PARTMODE_RAM);
> -	add_part(info, mds->active_volatile_bytes, mds->active_persistent_bytes,
> -		 CXL_PARTMODE_PMEM);
> -
> -	return 0;
> -}
> -EXPORT_SYMBOL_NS_GPL(cxl_mem_dpa_fetch, "CXL");
> -
>  int cxl_get_dirty_count(struct cxl_memdev_state *mds, u32 *count)
>  {
>  	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> index 97127d6067c4..d148a0c942aa 100644
> --- a/drivers/cxl/core/memdev.c
> +++ b/drivers/cxl/core/memdev.c
> @@ -556,6 +556,72 @@ bool is_cxl_memdev(const struct device *dev)
>  }
>  EXPORT_SYMBOL_NS_GPL(is_cxl_memdev, "CXL");
>  
> +static void add_part(struct cxl_dpa_info *info, u64 start, u64 size, enum cxl_partition_mode mode)
> +{
> +	int i = info->nr_partitions;
> +
> +	if (size == 0)
> +		return;
> +
> +	info->part[i].range = (struct range) {
> +		.start = start,
> +		.end = start + size - 1,
> +	};
> +	info->part[i].mode = mode;
> +	info->nr_partitions++;
> +}
> +
> +int cxl_mem_dpa_fetch(struct cxl_memdev_state *mds, struct cxl_dpa_info *info)
> +{
> +	struct cxl_dev_state *cxlds = &mds->cxlds;
> +	struct device *dev = cxlds->dev;
> +	int rc;
> +
> +	if (!cxlds->media_ready) {
> +		info->size = 0;
> +		return 0;
> +	}
> +
> +	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, mds->volatile_only_bytes,
> +			 mds->persistent_only_bytes, CXL_PARTMODE_PMEM);
> +		return 0;
> +	}
> +
> +	rc = cxl_mem_get_partition_info(mds);
> +	if (rc) {
> +		dev_err(dev, "Failed to query partition information\n");
> +		return rc;
> +	}
> +
> +	add_part(info, 0, mds->active_volatile_bytes, CXL_PARTMODE_RAM);
> +	add_part(info, mds->active_volatile_bytes, mds->active_persistent_bytes,
> +		 CXL_PARTMODE_PMEM);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_mem_dpa_fetch, "CXL");
> +
> +/**
> + * cxl_set_capacity: initialize dpa by a driver without a mailbox.
> + *
> + * @cxlds: pointer to cxl_dev_state
> + * @capacity: device volatile memory size
> + */
> +int cxl_set_capacity(struct cxl_dev_state *cxlds, u64 capacity)
> +{
> +	struct cxl_dpa_info range_info = {
> +		.size = capacity,
> +	};
> +
> +	add_part(&range_info, 0, capacity, CXL_PARTMODE_RAM);
> +	return cxl_dpa_setup(cxlds, &range_info);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_set_capacity, "CXL");
> +
>  /**
>   * set_exclusive_cxl_commands() - atomically disable user cxl commands
>   * @mds: The device state to operate on
> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
> index cdfbe546d8d8..651d26aa68dc 100644
> --- a/drivers/net/ethernet/sfc/efx_cxl.c
> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
> @@ -78,6 +78,10 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>  	 */
>  	cxl->cxlds.media_ready = true;
>  
> +	if (cxl_set_capacity(&cxl->cxlds, EFX_CTPIO_BUFFER_SIZE))
> +		return dev_err_probe(&pci_dev->dev, -ENODEV,
> +				     "dpa capacity setup failed\n");
> +
>  	probe_data->cxl = cxl;
>  
>  	return 0;
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index 3b9c8cb187a3..88dea6ac3769 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -243,4 +243,5 @@ struct cxl_dev_state *_devm_cxl_dev_state_create(struct device *dev,
>  int cxl_map_component_regs(const struct cxl_register_map *map,
>  			   struct cxl_component_regs *regs,
>  			   unsigned long map_mask);
> +int cxl_set_capacity(struct cxl_dev_state *cxlds, u64 capacity);
>  #endif /* __CXL_CXL_H__ */