[PATCH v2 06/21] cxl: Add callback to parse the DSLBIS subtable from CDAT

[Dave Jiang <dave.jiang@xxxxxxxxx>]

Provide a callback to parse the Device Scoped Latency and Bandwidth
Information Structure (DSLBIS) in the CDAT structures. The DSLBIS
contains the bandwidth and latency information that's tied to a DSMAS
handle. The driver will retrieve the read and write latency and
bandwidth associated with the DSMAS which is tied to a DPA range.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>

---
v2:
- Add size check to DSLIBIS table. (Lukas)
- Remove unnecessary entry type check. (Jonathan)
- Move data_type check to after match. (Jonathan)
- Skip unknown data type. (Jonathan)
- Add overflow check for unit multiply. (Jonathan)
- Use dev_warn() when entries parsing fail. (Jonathan)
---
 drivers/cxl/core/cdat.c |   41 +++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/cxlpci.h    |   34 +++++++++++++++++++++++++++++++++-
 drivers/cxl/port.c      |    9 ++++++++-
 3 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
index d068609fb6f9..0e88973e9f38 100644
--- a/drivers/cxl/core/cdat.c
+++ b/drivers/cxl/core/cdat.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright(c) 2023 Intel Corporation. All rights reserved. */
+#include <linux/overflow.h>
 #include "cxlpci.h"
 #include "cxl.h"
 
@@ -124,3 +125,43 @@ int cxl_dsmas_parse_entry(struct cdat_entry_header *header, void *arg)
 	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_dsmas_parse_entry, CXL);
+
+int cxl_dslbis_parse_entry(struct cdat_entry_header *header, void *arg)
+{
+	struct cdat_dslbis *dslbis = (struct cdat_dslbis *)header;
+	struct list_head *dsmas_list = (struct list_head *)arg;
+	struct dsmas_entry *dent;
+
+	if (dslbis->hdr.length != sizeof(*dslbis)) {
+		pr_warn("Malformed DSLBIS table length: (%lu:%u)\n",
+			(unsigned long)sizeof(*dslbis), dslbis->hdr.length);
+		return -EINVAL;
+	}
+
+	/* Unrecognized data type, we can skip */
+	if (dslbis->data_type >= HMAT_SLLBIS_DATA_TYPE_MAX)
+		return 0;
+
+	list_for_each_entry(dent, dsmas_list, list) {
+		u64 val;
+		int rc;
+
+		if (dslbis->handle != dent->handle)
+			continue;
+
+		/* Not a memory type, skip */
+		if ((dslbis->flags & DSLBIS_MEM_MASK) != DSLBIS_MEM_MEMORY)
+			return 0;
+
+		rc = check_mul_overflow(le64_to_cpu(dslbis->entry_base_unit),
+					le16_to_cpu(dslbis->entry[0]), &val);
+		if (unlikely(rc))
+			pr_warn("DSLBIS value overflowed!\n");
+
+		dent->qos[dslbis->data_type] = val;
+		break;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_dslbis_parse_entry, CXL);
diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
index 9a2468a93d83..1429de49e0c4 100644
--- a/drivers/cxl/cxlpci.h
+++ b/drivers/cxl/cxlpci.h
@@ -104,10 +104,21 @@ struct cdat_subtable_entry {
 	enum cdat_type type;
 };
 
+enum {
+	HMAT_SLLBIS_ACCESS_LATENCY = 0,
+	HMAT_SLLBIS_READ_LATENCY,
+	HMAT_SLLBIS_WRITE_LATENCY,
+	HMAT_SLLBIS_ACCESS_BANDWIDTH,
+	HMAT_SLLBIS_READ_BANDWIDTH,
+	HMAT_SLLBIS_WRITE_BANDWIDTH,
+	HMAT_SLLBIS_DATA_TYPE_MAX
+};
+
 struct dsmas_entry {
 	struct list_head list;
 	struct range dpa_range;
 	u8 handle;
+	u64 qos[HMAT_SLLBIS_DATA_TYPE_MAX];
 };
 
 /* Sub-table 0: Device Scoped Memory Affinity Structure (DSMAS) */
@@ -120,6 +131,23 @@ struct cdat_dsmas {
 	__le64 dpa_length;
 } __packed;
 
+/* Sub-table 1: Device Scoped Latency and Bandwidth Information Structure (DSLBIS) */
+struct cdat_dslbis {
+	struct cdat_entry_header hdr;
+	u8 handle;
+	u8 flags;
+	u8 data_type;
+	u8 reserved;
+	__le64 entry_base_unit;
+	__le16 entry[3];
+	__le16 reserved2;
+} __packed;
+
+/* Flags for subtable above */
+
+#define DSLBIS_MEM_MASK		GENMASK(3, 0)
+#define DSLBIS_MEM_MEMORY	0
+
 int devm_cxl_port_enumerate_dports(struct cxl_port *port);
 struct cxl_dev_state;
 int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
@@ -136,5 +164,9 @@ cdat_table_parse(dsmas);
 cdat_table_parse(dslbis);
 cdat_table_parse(sslbis);
 
-int cxl_dsmas_parse_entry(struct cdat_entry_header *header, void *arg);
+#define cxl_parse_entry(x) \
+int cxl_##x##_parse_entry(struct cdat_entry_header *header, void *arg)
+
+cxl_parse_entry(dsmas);
+cxl_parse_entry(dslbis);
 #endif /* __CXL_PCI_H__ */
diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
index c8136797d528..6f2b327f7128 100644
--- a/drivers/cxl/port.c
+++ b/drivers/cxl/port.c
@@ -152,8 +152,15 @@ static int cxl_port_probe(struct device *dev)
 			rc = cdat_table_parse_dsmas(port->cdat.table,
 						    cxl_dsmas_parse_entry,
 						    (void *)&dsmas_list);
-			if (rc < 0)
+			if (rc > 0) {
+				rc = cdat_table_parse_dslbis(port->cdat.table,
+							     cxl_dslbis_parse_entry,
+							     (void *)&dsmas_list);
+				if (rc <= 0)
+					dev_warn(dev, "Failed to parse DSLBIS: %d\n", rc);
+			} else {
 				dev_warn(dev, "Failed to parse DSMAS: %d\n", rc);
+			}
 
 			dsmas_list_destroy(&dsmas_list);
 		}