Re: [PATCH v10 01/31] cxl/mbox: Flag support for Dynamic Capacity Devices (DCD)

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

On 5/23/26 2:42 AM, Anisa Su wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> Per the CXL 3.1 specification software must check the Command Effects

May as well update to CXL r4.0

> Log (CEL) for dynamic capacity command support.
> 
> Detect support for the DCD commands while reading the CEL, including:
> 
> 	Get DC Config
> 	Get DC Extent List
> 	Add DC Response
> 	Release DC
> 
> Based on an original patch by Navneet Singh.
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>

missing Anisa sign off

> 
> ---
> Changes:
> [anisa: rebase]
> ---
>  drivers/cxl/core/mbox.c | 43 +++++++++++++++++++++++++++++++++++++++++
>  drivers/cxl/cxlmem.h    | 15 ++++++++++++++
>  2 files changed, 58 insertions(+)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index aaa5c6277ebf..7ef5708bf210 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -165,6 +165,42 @@ static void cxl_set_security_cmd_enabled(struct cxl_security_state *security,
>  	}
>  }
>  
> +static bool cxl_is_dcd_command(u16 opcode)
> +{
> +#define CXL_MBOX_OP_DCD_CMDS 0x48
> +
> +	return (opcode >> 8) == CXL_MBOX_OP_DCD_CMDS;
> +}
> +
> +static void cxl_set_dcd_cmd_enabled(struct cxl_memdev_state *mds, u16 opcode,
> +				    unsigned long *cmd_mask)

mds not used, consider drop

> +{
> +	switch (opcode) {
> +	case CXL_MBOX_OP_GET_DC_CONFIG:
> +		set_bit(CXL_DCD_ENABLED_GET_CONFIG, cmd_mask);
> +		break;
> +	case CXL_MBOX_OP_GET_DC_EXTENT_LIST:
> +		set_bit(CXL_DCD_ENABLED_GET_EXTENT_LIST, cmd_mask);
> +		break;
> +	case CXL_MBOX_OP_ADD_DC_RESPONSE:
> +		set_bit(CXL_DCD_ENABLED_ADD_RESPONSE, cmd_mask);
> +		break;
> +	case CXL_MBOX_OP_RELEASE_DC:
> +		set_bit(CXL_DCD_ENABLED_RELEASE, cmd_mask);
> +		break;
> +	default:
> +		break;
> +	}
> +}
> +
> +static bool cxl_verify_dcd_cmds(struct cxl_memdev_state *mds, unsigned long *cmds_seen)

mds not used. consider drop

> +{
> +	DECLARE_BITMAP(all_cmds, CXL_DCD_ENABLED_MAX);
> +
> +	bitmap_fill(all_cmds, CXL_DCD_ENABLED_MAX);
> +	return bitmap_equal(cmds_seen, all_cmds, CXL_DCD_ENABLED_MAX);

Above lines can be replaced with:
return bitmap_full(cmds_seen, CXL_DCD_ENABLED_MAX);

> +}
> +
>  static bool cxl_is_poison_command(u16 opcode)
>  {
>  #define CXL_MBOX_OP_POISON_CMDS 0x43
> @@ -757,6 +793,7 @@ static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
>  	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
>  	struct cxl_cel_entry *cel_entry;
>  	const int cel_entries = size / sizeof(*cel_entry);
> +	DECLARE_BITMAP(dcd_cmds, CXL_DCD_ENABLED_MAX);

Need to zero out the declared bitmap 'dcd_cmds' on stack before using.

	DECLARE_BITMAP(dcd_cmds, CXL_DCD_ENABLED_MAX) = {};

>  	struct device *dev = mds->cxlds.dev;
>  	int i, ro_cmds = 0, wr_cmds = 0;
>  
> @@ -785,11 +822,17 @@ static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
>  			enabled++;
>  		}
>  
> +		if (cxl_is_dcd_command(opcode)) {
> +			cxl_set_dcd_cmd_enabled(mds, opcode, dcd_cmds);
> +			enabled++;
> +		}
> +
>  		dev_dbg(dev, "Opcode 0x%04x %s\n", opcode,
>  			enabled ? "enabled" : "unsupported by driver");
>  	}
>  
>  	set_features_cap(cxl_mbox, ro_cmds, wr_cmds);
> +	mds->dcd_supported = cxl_verify_dcd_cmds(mds, dcd_cmds);
>  }
>  
>  static struct cxl_mbox_get_supported_logs *cxl_get_gsl(struct cxl_memdev_state *mds)
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 776c50d1db51..53444af448d7 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -230,6 +230,15 @@ struct cxl_event_state {
>  	struct mutex log_lock;
>  };
>  
> +/* Device enabled DCD commands */
> +enum dcd_cmd_enabled_bits {
> +	CXL_DCD_ENABLED_GET_CONFIG,
> +	CXL_DCD_ENABLED_GET_EXTENT_LIST,
> +	CXL_DCD_ENABLED_ADD_RESPONSE,
> +	CXL_DCD_ENABLED_RELEASE,
> +	CXL_DCD_ENABLED_MAX
> +};
> +

would be nice to have comment point to where in the spec this is

DJ

>  /* Device enabled poison commands */
>  enum poison_cmd_enabled_bits {
>  	CXL_POISON_ENABLED_LIST,
> @@ -405,6 +414,7 @@ static inline struct cxl_dev_state *mbox_to_cxlds(struct cxl_mailbox *cxl_mbox)
>   * @partition_align_bytes: alignment size for partition-able capacity
>   * @active_volatile_bytes: sum of hard + soft volatile
>   * @active_persistent_bytes: sum of hard + soft persistent
> + * @dcd_supported: all DCD commands are supported
>   * @event: event log driver state
>   * @poison: poison driver state info
>   * @security: security driver state info
> @@ -424,6 +434,7 @@ struct cxl_memdev_state {
>  	u64 partition_align_bytes;
>  	u64 active_volatile_bytes;
>  	u64 active_persistent_bytes;
> +	bool dcd_supported;
>  
>  	struct cxl_event_state event;
>  	struct cxl_poison_state poison;
> @@ -485,6 +496,10 @@ enum cxl_opcode {
>  	CXL_MBOX_OP_UNLOCK		= 0x4503,
>  	CXL_MBOX_OP_FREEZE_SECURITY	= 0x4504,
>  	CXL_MBOX_OP_PASSPHRASE_SECURE_ERASE	= 0x4505,
> +	CXL_MBOX_OP_GET_DC_CONFIG	= 0x4800,
> +	CXL_MBOX_OP_GET_DC_EXTENT_LIST	= 0x4801,
> +	CXL_MBOX_OP_ADD_DC_RESPONSE	= 0x4802,
> +	CXL_MBOX_OP_RELEASE_DC		= 0x4803,
>  	CXL_MBOX_OP_MAX			= 0x10000
>  };
>