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

[Anisa Su <anisa.su887@gmail.com>]

On Wed, May 27, 2026 at 02:34:31PM -0700, Dave Jiang wrote:
> 
> 
> 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
> 
Updated!
> > 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
> 
Added!
> > 
> > ---
> > 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
> 
dropped
> > +{
> > +	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
> 
also dropped
> > +{
> > +	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);
> 
replaced
> > +}
> > +
> >  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) = {};
> 
done :)
> >  	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
> 
Added
> DJ
> 
Thanks!
Anisa
> >  /* 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
> >  };
> >  
>