netdev - [PATCH v6 04/28] cxl/pci: add check for validating capabilities

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Message-ID: <20241202171222.62595-5-alejandro.lucero-palau@amd.com>
Date: Mon, 2 Dec 2024 17:11:58 +0000
From: <alejandro.lucero-palau@....com>
To: <linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
	<dan.j.williams@...el.com>, <martin.habets@...inx.com>,
	<edward.cree@....com>, <davem@...emloft.net>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <edumazet@...gle.com>, <dave.jiang@...el.com>
CC: Alejandro Lucero <alucerop@....com>
Subject: [PATCH v6 04/28] cxl/pci: add check for validating capabilities

From: Alejandro Lucero <alucerop@....com>

During CXL device initialization supported capabilities by the device
are discovered. Type3 and Type2 devices have different mandatory
capabilities and a Type2 expects a specific set including optional
capabilities.

Add a function for checking expected capabilities against those found
during initialization and allow those mandatory/expected capabilities to
be a subset of the capabilities found.

Rely on this function for validating capabilities instead of when CXL
regs are probed.

Signed-off-by: Alejandro Lucero <alucerop@....com>
---
 drivers/cxl/core/pci.c  | 16 ++++++++++++++++
 drivers/cxl/core/regs.c |  9 ---------
 drivers/cxl/pci.c       | 24 ++++++++++++++++++++++++
 include/cxl/cxl.h       |  3 +++
 4 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 7114d632be04..a85b96eebfd3 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -8,6 +8,7 @@
 #include <linux/pci.h>
 #include <linux/pci-doe.h>
 #include <linux/aer.h>
+#include <cxl/cxl.h>
 #include <cxlpci.h>
 #include <cxlmem.h>
 #include <cxl.h>
@@ -1055,3 +1056,18 @@ int cxl_pci_get_bandwidth(struct pci_dev *pdev, struct access_coordinate *c)
 
 	return 0;
 }
+
+bool cxl_pci_check_caps(struct cxl_dev_state *cxlds, unsigned long *expected_caps,
+			unsigned long *current_caps)
+{
+
+	if (current_caps)
+		bitmap_copy(current_caps, cxlds->capabilities, CXL_MAX_CAPS);
+
+	dev_dbg(cxlds->dev, "Checking cxlds caps 0x%08lx vs expected caps 0x%08lx\n",
+		*cxlds->capabilities, *expected_caps);
+
+	/* Checking a minimum of mandatory/expected capabilities */
+	return bitmap_subset(expected_caps, cxlds->capabilities, CXL_MAX_CAPS);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_pci_check_caps, CXL);
diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
index fe835f6df866..70378bb80b33 100644
--- a/drivers/cxl/core/regs.c
+++ b/drivers/cxl/core/regs.c
@@ -444,15 +444,6 @@ static int cxl_probe_regs(struct cxl_register_map *map, unsigned long *caps)
 	case CXL_REGLOC_RBI_MEMDEV:
 		dev_map = &map->device_map;
 		cxl_probe_device_regs(host, base, dev_map, caps);
-		if (!dev_map->status.valid || !dev_map->mbox.valid ||
-		    !dev_map->memdev.valid) {
-			dev_err(host, "registers not found: %s%s%s\n",
-				!dev_map->status.valid ? "status " : "",
-				!dev_map->mbox.valid ? "mbox " : "",
-				!dev_map->memdev.valid ? "memdev " : "");
-			return -ENXIO;
-		}
-
 		dev_dbg(host, "Probing device registers...\n");
 		break;
 	default:
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index f6071bde437b..822030843b2f 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -903,6 +903,8 @@ __ATTRIBUTE_GROUPS(cxl_rcd);
 static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
 	struct pci_host_bridge *host_bridge = pci_find_host_bridge(pdev->bus);
+	DECLARE_BITMAP(expected, CXL_MAX_CAPS);
+	DECLARE_BITMAP(found, CXL_MAX_CAPS);
 	struct cxl_memdev_state *mds;
 	struct cxl_dev_state *cxlds;
 	struct cxl_register_map map;
@@ -964,6 +966,28 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (rc)
 		dev_dbg(&pdev->dev, "Failed to map RAS capability.\n");
 
+	bitmap_clear(expected, 0, CXL_MAX_CAPS);
+
+	/*
+	 * These are the mandatory capabilities for a Type3 device.
+	 * Only checking capabilities used by current Linux drivers.
+	 */
+	bitmap_set(expected, CXL_DEV_CAP_HDM, 1);
+	bitmap_set(expected, CXL_DEV_CAP_DEV_STATUS, 1);
+	bitmap_set(expected, CXL_DEV_CAP_MAILBOX_PRIMARY, 1);
+	bitmap_set(expected, CXL_DEV_CAP_DEV_STATUS, 1);
+
+	/*
+	 * Checking mandatory caps are there as, at least, a subset of those
+	 * found.
+	 */
+	if (!cxl_pci_check_caps(cxlds, expected, found)) {
+		dev_err(&pdev->dev,
+			"Expected mandatory capabilities not found: (%08lx - %08lx)\n",
+			*expected, *found);
+		return -ENXIO;
+	}
+
 	rc = cxl_pci_type3_init_mailbox(cxlds);
 	if (rc)
 		return rc;
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index f656fcd4945f..05f06bfd2c29 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -37,4 +37,7 @@ void cxl_set_dvsec(struct cxl_dev_state *cxlds, u16 dvsec);
 void cxl_set_serial(struct cxl_dev_state *cxlds, u64 serial);
 int cxl_set_resource(struct cxl_dev_state *cxlds, struct resource res,
 		     enum cxl_resource);
+bool cxl_pci_check_caps(struct cxl_dev_state *cxlds,
+			unsigned long *expected_caps,
+			unsigned long *current_caps);
 #endif
-- 
2.17.1