Re: [RFC PATCH v2 3/3] cxl/test: Exercise explicit Type-2 RAM region creation

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

On 10/7/26 2:05 AM, Richard Cheng wrote:
> Add a second mock Type-2 accelerator without a FW-provided region.
> Register its memdev, try attachment, and explicitly create a 256 MB RAM
> region when needed.
> 
> Check the returned HPA range and retain the original accelerator on
> devm_cxl_probe_mem(). Preserve MANUAL DEVMEM configuration after
> disabled reply or failed saved-state restoration.
> 

Thanks for doing this Richard! Really appreciate it. Also nice to see an example of how it will be used.

DJ

> Signed-off-by: Richard Cheng <icheng@nvidia.com>
> ---
> Changelog:
> 
> v1 -> v2:
> - Use separate registration, creation and attachment APIs
> - Request 256 MB from 512 MB capacity
> - Preserve DEVMEM config after failed restoration
> ---
>  tools/testing/cxl/test/accel.c | 28 +++++++++++++++++++-
>  tools/testing/cxl/test/cxl.c   | 47 +++++++++++++++++++++++++++++-----
>  2 files changed, 68 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/testing/cxl/test/accel.c b/tools/testing/cxl/test/accel.c
> index 8e6f4687ca02..83962702145d 100644
> --- a/tools/testing/cxl/test/accel.c
> +++ b/tools/testing/cxl/test/accel.c
> @@ -20,6 +20,7 @@ static int cxl_mock_accel_probe(struct platform_device *pdev)
>  	struct cxl_dev_state *cxlds;
>  	struct cxl_memdev *cxlmd;
>  	struct range mock_range;
> +	u64 region_size = pdev->id == 0 ? SZ_512M : SZ_256M;
>  	int rc;
>  
>  	cxl_accel = devm_cxl_dev_state_create(&pdev->dev, CXL_DEVTYPE_DEVMEM,
> @@ -35,9 +36,34 @@ static int cxl_mock_accel_probe(struct platform_device *pdev)
>  	if (rc)
>  		return rc;
>  
> -	cxlmd = devm_cxl_probe_mem(cxlds, &mock_range);
> +	/* Keep the firmware-configured accelerator on the legacy API. */
> +	if (pdev->id == 0)
> +		cxlmd = devm_cxl_probe_mem(cxlds, &mock_range);
> +	else
> +		cxlmd = devm_cxl_register_mem(cxlds);
>  	if (IS_ERR(cxlmd))
>  		return PTR_ERR(cxlmd);
> +
> +	if (pdev->id != 0) {
> +		rc = devm_cxl_attach_mem_region(cxlmd, &mock_range);
> +		if (rc == -ENXIO) {
> +			/* The provider chooses to map half its volatile capacity. */
> +			rc = devm_cxl_create_ram_region(cxlmd, region_size);
> +			if (rc)
> +				return rc;
> +			rc = devm_cxl_attach_mem_region(cxlmd, &mock_range);
> +		}
> +		if (rc)
> +			return rc;
> +	}
> +
> +	if (mock_range.start > mock_range.end ||
> +	    range_len(&mock_range) != region_size) {
> +		dev_err(dev,
> +			"accelerator%d returned invalid HPA range %pra (expected %llu bytes)\n",
> +			pdev->id, &mock_range, region_size);
> +		return -ERANGE;
> +	}
>  	cxl_accel->cxlmd = cxlmd;
>  
>  	dev_dbg(dev, "Probed mock accelerator with range %pra\n", &mock_range);
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index 3eb1051b1ee8..4fab2572a1aa 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -29,7 +29,7 @@ static bool mock_zero_size_decoders;
>  #define NR_CXL_SWITCH_PORTS 2
>  #define NR_CXL_PORT_DECODERS 8
>  #define NR_BRIDGES (NR_CXL_HOST_BRIDGES + NR_CXL_SINGLE_HOST + NR_CXL_RCH)
> -#define NR_CXL_TYPE2_ACCEL 1
> +#define NR_CXL_TYPE2_ACCEL 2
>  
>  #define MOCK_AUTO_REGION_SIZE_DEFAULT SZ_512M
>  static int mock_auto_region_size = MOCK_AUTO_REGION_SIZE_DEFAULT;
> @@ -494,7 +494,17 @@ static void cfmws_elc_update(struct acpi_cedt_cfmws *window, int index)
>  
>  static void update_type2_cfmws(void)
>  {
> +	struct acpi_cedt_cfmws *window = &mock_cedt.cfmws1.cfmws;
> +
>  	memcpy(&mock_cedt.cfmws0.cfmws, &type2_cfmws0, sizeof(type2_cfmws0));
> +
> +	/* Give the unconfigured accelerator its own single-target window. */
> +	window->header.length = sizeof(*window) +
> +				sizeof(mock_cedt.cfmws1.target[0]);
> +	window->interleave_ways = 0;
> +	window->restrictions = ACPI_CEDT_CFMWS_RESTRICT_DEVMEM |
> +			       ACPI_CEDT_CFMWS_RESTRICT_VOLATILE;
> +	mock_cedt.cfmws1.target[0] = 1;
>  }
>  
>  static int populate_cedt(void)
> @@ -1122,6 +1132,7 @@ enum cxld_init_type {
>  	MOCK_DECODER_INIT_SAVED,
>  	MOCK_DECODER_INIT_TYPE3_AUTO,
>  	MOCK_DECODER_INIT_TYPE2_AUTO,
> +	MOCK_DECODER_INIT_TYPE2_MANUAL,
>  };
>  
>  static enum cxld_init_type get_decoder_init_type(struct cxl_decoder *cxld,
> @@ -1131,12 +1142,13 @@ static enum cxld_init_type get_decoder_init_type(struct cxl_decoder *cxld,
>  {
>  	struct cxl_test_decoder *found_td = cxld_registry_find(cxld);
>  
> -	if (found_td) {
> -		*td = found_td;
> -		return MOCK_DECODER_INIT_SAVED;
> -	}
> +	*td = found_td;
> +	if (type2_test && is_endpoint_decoder(&cxld->dev) && pdev->id == 1 &&
> +	    cxld->id == 0)
> +		return MOCK_DECODER_INIT_TYPE2_MANUAL;
>  
> -	*td = NULL;
> +	if (found_td)
> +		return MOCK_DECODER_INIT_SAVED;
>  
>  	/*
>  	 * The first decoder on the first 2 devices on the first switch
> @@ -1170,6 +1182,27 @@ static bool mock_decoder_handle_saved(struct cxl_decoder *cxld, struct cxl_test_
>  	return false;
>  }
>  
> +static bool mock_init_hdm_type2_manual(struct cxl_endpoint_decoder *cxled,
> +				       struct cxl_test_decoder *td)
> +{
> +	struct cxl_decoder *cxld = &cxled->cxld;
> +
> +	if (td) {
> +		if (mock_decoder_handle_saved(cxld, td))
> +			return true;
> +	} else {
> +		init_disabled_mock_decoder(cxld);
> +	}
> +
> +	/* Preserve DEVMEM on disabled replay and failed saved-state restore. */
> +	cxld->target_type = CXL_DECODER_DEVMEM;
> +	cxld->interleave_granularity = CXL_DECODER_MIN_GRANULARITY;
> +	if (!td)
> +		WARN_ON_ONCE(!cxld_registry_new(cxld));
> +
> +	return false;
> +}
> +
>  static void mock_init_hdm_type2_cxled(struct cxl_endpoint_decoder *cxled,
>  				      struct cxl_port *port)
>  {
> @@ -1445,6 +1478,8 @@ static bool mock_init_hdm_decoder(struct cxl_decoder *cxld)
>  	case MOCK_DECODER_INIT_TYPE2_AUTO:
>  		mock_init_hdm_type2_cxled(cxled, port);
>  		return false;
> +	case MOCK_DECODER_INIT_TYPE2_MANUAL:
> +		return mock_init_hdm_type2_manual(cxled, td);
>  	default:
>  		return false;
>  	}