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

[Richard Cheng <icheng@nvidia.com>]

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.

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;
 	}
-- 
2.43.0