Re: [RFC 4/5] cxl: Set type of region to that of the first endpoint

[Ben Cheatham]

On 9/24/24 9:46 PM, Huang Ying wrote:
> The type of region is hard-coded as type 3 expander now, because this
> is the only supported device type.  As a preparation to support type 2
> accelerators, we set the type of region to that of the first endpoint.
> Then, we will check whether the type of region is same as the type of
> other endpoints of the region.  Because what we really need is to make
> sure the type of all endpoints of a region is same.
> 
> The target type of endpoint devices comes from expander/accelerator
> device drivers via struct cxl_dev_state.
> 
> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
> Cc: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
> Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
> Cc: Alison Schofield <alison.schofield@xxxxxxxxx>
> Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
> Cc: Alejandro Lucero <alucerop@xxxxxxx>
> ---
>  drivers/cxl/acpi.c        |  1 -
>  drivers/cxl/core/hdm.c    | 28 +++++++++++++---------------
>  drivers/cxl/core/port.c   |  2 ++
>  drivers/cxl/core/region.c | 13 +++++++------
>  drivers/cxl/cxl.h         |  1 +
>  5 files changed, 23 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 21486e471305..29c2a44b122c 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -382,7 +382,6 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
>  
>  	cxld = &cxlrd->cxlsd.cxld;
>  	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
> -	cxld->target_type = CXL_DECODER_EXPANDER;
>  	cxld->hpa_range = (struct range) {
>  		.start = cfmws->base_hpa,
>  		.end = cfmws->base_hpa + cfmws->window_size - 1,
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index 478fb6691759..c9accf8be71f 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -841,18 +841,25 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
>  		.end = base + size - 1,
>  	};
>  
> +	if (cxled) {
> +		struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> +		struct cxl_dev_state *cxlds = cxlmd->cxlds;
> +
> +		if (cxlds->type == CXL_DEVTYPE_CLASSMEM)
> +			cxld->target_type = CXL_DECODER_EXPANDER;
> +		else
> +			cxld->target_type = CXL_DECODER_ACCEL;
> +	}
> +
>  	/* decoders are enabled if committed */
>  	if (committed) {
>  		cxld->flags |= CXL_DECODER_F_ENABLE;
>  		if (ctrl & CXL_HDM_DECODER0_CTRL_LOCK)
>  			cxld->flags |= CXL_DECODER_F_LOCK;
> -		if (FIELD_GET(CXL_HDM_DECODER0_CTRL_HOSTONLY, ctrl)) {
> -			cxld->target_type = CXL_DECODER_EXPANDER;
> +		if (FIELD_GET(CXL_HDM_DECODER0_CTRL_HOSTONLY, ctrl))
>  			cxld->coherence = CXL_DECODER_HOSTONLYCOH;
> -		} else {
> -			cxld->target_type = CXL_DECODER_ACCEL;
> +		else
>  			cxld->coherence = CXL_DECODER_DEVCOH;
> -		}
>  
>  		guard(rwsem_write)(&cxl_region_rwsem);
>  		if (cxld->id != cxl_num_decoders_committed(port)) {
> @@ -874,21 +881,12 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
>  			struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
>  			struct cxl_dev_state *cxlds = cxlmd->cxlds;
>  
> -			/*
> -			 * Default by devtype until a device arrives that needs
> -			 * more precision.
> -			 */
> -			if (cxlds->type == CXL_DEVTYPE_CLASSMEM)
> -				cxld->target_type = CXL_DECODER_EXPANDER;
> -			else
> -				cxld->target_type = CXL_DECODER_ACCEL;
>  			if (cxlds->coherence == CXL_DEVCOH_HOSTONLY)
>  				cxld->coherence = CXL_DECODER_HOSTONLYCOH;
>  			else
>  				cxld->coherence = CXL_DECODER_DEVCOH;
>  		} else {
> -			/* To be overridden by region type/coherence at commit time */
> -			cxld->target_type = CXL_DECODER_EXPANDER;
> +			/* To be overridden by region coherence at commit time */
>  			cxld->coherence = CXL_DECODER_HOSTONLYCOH;
>  		}
>  
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 2dee78e9b90c..5633b7316cb3 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -139,6 +139,8 @@ static ssize_t target_type_show(struct device *dev,
>  		return sysfs_emit(buf, "accelerator\n");
>  	case CXL_DECODER_EXPANDER:
>  		return sysfs_emit(buf, "expander\n");
> +	default:
> +		break;

You can drop this imo. It doesn't change anything functionally considering
the break is immediately followed by a return.

Thanks,
Ben

>  	}
>  	return -ENXIO;
>  }
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index cec7d08b6f44..9c68ec445128 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1926,7 +1926,10 @@ static int cxl_region_attach(struct cxl_region *cxlr,
>  		return -ENXIO;
>  	}
>  
> -	if (cxled->cxld.target_type != cxlr->type) {
> +	/* Set the type of region to that of the first endpoint */
> +	if (cxlr->type == CXL_DECODER_INVALID) {
> +		cxlr->type = cxled->cxld.target_type;
> +	} else if (cxled->cxld.target_type != cxlr->type) {
>  		dev_dbg(&cxlr->dev, "%s:%s type mismatch: %d vs %d\n",
>  			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
>  			cxled->cxld.target_type, cxlr->type);
> @@ -2482,7 +2485,6 @@ static int cxl_region_calculate_adistance(struct notifier_block *nb,
>   * @cxlrd: root decoder
>   * @id: memregion id to create, or memregion_free() on failure
>   * @mode: mode for the endpoint decoders of this region
> - * @type: select whether this is an expander or accelerator (type-2 or type-3)
>   *
>   * This is the second step of region initialization. Regions exist within an
>   * address space which is mapped by a @cxlrd.
> @@ -2492,8 +2494,7 @@ static int cxl_region_calculate_adistance(struct notifier_block *nb,
>   */
>  static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
>  					      int id,
> -					      enum cxl_decoder_mode mode,
> -					      enum cxl_decoder_type type)
> +					      enum cxl_decoder_mode mode)
>  {
>  	struct cxl_port *port = to_cxl_port(cxlrd->cxlsd.cxld.dev.parent);
>  	struct cxl_region *cxlr;
> @@ -2504,7 +2505,7 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
>  	if (IS_ERR(cxlr))
>  		return cxlr;
>  	cxlr->mode = mode;
> -	cxlr->type = type;
> +	cxlr->type = CXL_DECODER_INVALID;
>  
>  	dev = &cxlr->dev;
>  	rc = dev_set_name(dev, "region%d", id);
> @@ -2576,7 +2577,7 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
>  		return ERR_PTR(-EBUSY);
>  	}
>  
> -	return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_EXPANDER);
> +	return devm_cxl_add_region(cxlrd, id, mode);
>  }
>  
>  static ssize_t create_pmem_region_store(struct device *dev,
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 99398c868d82..2a2d2c483654 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -324,6 +324,7 @@ resource_size_t cxl_rcd_component_reg_phys(struct device *dev,
>  #define CXL_DECODER_F_MASK        GENMASK(5, 0)
>  
>  enum cxl_decoder_type {
> +	CXL_DECODER_INVALID,
>  	CXL_DECODER_ACCEL = 2,
>  	CXL_DECODER_EXPANDER = 3,
>  };