[v7,02/11] cxl: Add callback to parse the DSLBIS subtable from CDAT

Commit Message

Dave Jiang June 16, 2023, 9:41 p.m. UTC

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.

Coherent Device Attribute Table 1.03 2.1 Device Scoped Latency and
Bandwidth Information Structure (DSLBIS)

Reviewed-by: Jonathan Cameron <[e-mail]>
Signed-off-by: Dave Jiang <[e-mail]>

---
v6:
- Clarify cxl_cdat_endpoint_process() error paths for readability. (Jonathan)
- Adjust dslbis ptr from header.
v5:
- Remove macro for common headers. (Jonathan)
- Use acpi_table_parse_cdat().
- Remove unlikely(). (Dan)
v3:
- Added spec section in commit header. (Alison)
- Remove void * recast. (Alison)
- Rework comment. (Alison)
- Move CDAT parse to cxl_endpoint_port_probe()
- Convert to use 'struct node_hmem_attrs'

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 |  102 ++++++++++++++++++++++++++++++++++++++++++++++-
 drivers/cxl/cxl.h       |    2 +
 2 files changed, 102 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
index a858fd1b5744..361983393666 100644
--- a/drivers/cxl/core/cdat.c
+++ b/drivers/cxl/core/cdat.c
@@ -2,6 +2,7 @@ 
 /* Copyright(c) 2023 Intel Corporation. All rights reserved. */
 #include <linux/acpi.h>
 #include <linux/fw_table.h>
+#include <linux/overflow.h>
 #include "cxlpci.h"
 #include "cxl.h"
 
@@ -37,10 +38,107 @@  static int cdat_dsmas_handler(union acpi_subtable_headers *header, void *arg,
 	return 0;
 }
 
+static void cxl_access_coordinate_set(struct access_coordinate *coord,
+				      int access, unsigned int val)
+{
+	switch (access) {
+	case ACPI_HMAT_ACCESS_LATENCY:
+		coord->read_latency = val;
+		coord->write_latency = val;
+		break;
+	case ACPI_HMAT_READ_LATENCY:
+		coord->read_latency = val;
+		break;
+	case ACPI_HMAT_WRITE_LATENCY:
+		coord->write_latency = val;
+		break;
+	case ACPI_HMAT_ACCESS_BANDWIDTH:
+		coord->read_bandwidth = val;
+		coord->write_bandwidth = val;
+		break;
+	case ACPI_HMAT_READ_BANDWIDTH:
+		coord->read_bandwidth = val;
+		break;
+	case ACPI_HMAT_WRITE_BANDWIDTH:
+		coord->write_bandwidth = val;
+		break;
+	}
+}
+
+static int cdat_dslbis_handler(union acpi_subtable_headers *header, void *arg,
+			       const unsigned long end)
+{
+	struct acpi_cdat_header *hdr = &header->cdat;
+	struct acpi_cdat_dslbis *dslbis;
+	int size = sizeof(*hdr) + sizeof(*dslbis);
+	struct list_head *dsmas_list = arg;
+	struct dsmas_entry *dent;
+	u16 len;
+
+	len = le16_to_cpu((__force __le16)hdr->length);
+	if (len != size || (unsigned long)hdr + len > end) {
+		pr_warn("Malformed DSLBIS table length: (%u:%u)\n", size, len);
+		return -EINVAL;
+	}
+
+	/* Skip common header */
+	dslbis = (struct acpi_cdat_dslbis *)(hdr + 1);
+
+	/* Skip unrecognized data type */
+	if (dslbis->data_type > ACPI_HMAT_WRITE_BANDWIDTH)
+		return 0;
+
+	list_for_each_entry(dent, dsmas_list, list) {
+		__le64 le_base;
+		__le16 le_val;
+		u64 val;
+		int rc;
+
+		if (dslbis->handle != dent->handle)
+			continue;
+
+		/* Not a memory type, skip */
+		if ((dslbis->flags & ACPI_HMAT_MEMORY_HIERARCHY) !=
+		    ACPI_HMAT_MEMORY)
+			return 0;
+
+		le_base = (__force __le64)dslbis->entry_base_unit;
+		le_val = (__force __le16)dslbis->entry[0];
+		rc = check_mul_overflow(le64_to_cpu(le_base),
+					le16_to_cpu(le_val), &val);
+		if (rc)
+			pr_warn("DSLBIS value overflowed.\n");
+
+		cxl_access_coordinate_set(&dent->coord, dslbis->data_type, val);
+		break;
+	}
+
+	return 0;
+}
+
+static int cdat_table_parse_output(int rc)
+{
+	if (rc < 0)
+		return rc;
+	if (rc == 0)
+		return -ENOENT;
+
+	return 0;
+}
+
 int cxl_cdat_endpoint_process(struct cxl_port *port, struct list_head *list)
 {
-	return cdat_table_parse(ACPI_CDAT_TYPE_DSMAS, cdat_dsmas_handler,
-				list, port->cdat.table);
+	int rc;
+
+	rc = cdat_table_parse(ACPI_CDAT_TYPE_DSMAS, cdat_dsmas_handler,
+			      list, port->cdat.table);
+	rc = cdat_table_parse_output(rc);
+	if (rc)
+		return rc;
+
+	rc = cdat_table_parse(ACPI_CDAT_TYPE_DSLBIS, cdat_dslbis_handler,
+			      list, port->cdat.table);
+	return cdat_table_parse_output(rc);
 }
 EXPORT_SYMBOL_NS_GPL(cxl_cdat_endpoint_process, CXL);
 
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f4b6b34721f9..b431847c4eb5 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -8,6 +8,7 @@ 
 #include <linux/bitfield.h>
 #include <linux/bitops.h>
 #include <linux/list.h>
+#include <linux/node.h>
 #include <linux/log2.h>
 #include <linux/io.h>
 
@@ -798,6 +799,7 @@  struct dsmas_entry {
 	struct list_head list;
 	struct range dpa_range;
 	u8 handle;
+	struct access_coordinate coord;
 };
 
 #ifdef CONFIG_FIRMWARE_TABLE