cxl: Add callback to parse the DSMAS subtables from CDAT

Provide a callback function to the CDAT parser in order to parse the
Device Scoped Memory Affinity Structure (DSMAS). Each DSMAS structure
contains the DPA range and its associated attributes in each entry. See
the CDAT specification for details. The device handle and the DPA range
is saved and to be associated with the DSLBIS locality data when the
DSLBIS entries are parsed. The xarray is a local variable. When the
total path performance data is calculated and storred this xarray can be
discarded.

Coherent Device Attribute Table 1.03 2.1 Device Scoped memory Affinity
Structure (DSMAS)

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/170319619355.2212653.2675953129671561293.stgit@djiang5-mobl3
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

2 files changed, 93 insertions, 0 deletions

diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index 1f66b5d4d935..9259bcc6773c 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -13,5 +13,6 @@ cxl_core-y += mbox.o
 cxl_core-y += pci.o
 cxl_core-y += hdm.o
 cxl_core-y += pmu.o
+cxl_core-y += cdat.o
 cxl_core-$(CONFIG_TRACING) += trace.o
 cxl_core-$(CONFIG_CXL_REGION) += region.o
diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
new file mode 100644
index 000000000000..9bf4f53bf77f
--- /dev/null
+++ b/drivers/cxl/core/cdat.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2023 Intel Corporation. All rights reserved. */
+#include <linux/acpi.h>
+#include <linux/xarray.h>
+#include <linux/fw_table.h>
+#include "cxlpci.h"
+#include "cxl.h"
+
+struct dsmas_entry {
+	struct range dpa_range;
+	u8 handle;
+};
+
+static int cdat_dsmas_handler(union acpi_subtable_headers *header, void *arg,
+			      const unsigned long end)
+{
+	struct acpi_cdat_header *hdr = &header->cdat;
+	struct acpi_cdat_dsmas *dsmas;
+	int size = sizeof(*hdr) + sizeof(*dsmas);
+	struct xarray *dsmas_xa = arg;
+	struct dsmas_entry *dent;
+	u16 len;
+	int rc;
+
+	len = le16_to_cpu((__force __le16)hdr->length);
+	if (len != size || (unsigned long)hdr + len > end) {
+		pr_warn("Malformed DSMAS table length: (%u:%u)\n", size, len);
+		return -EINVAL;
+	}
+
+	/* Skip common header */
+	dsmas = (struct acpi_cdat_dsmas *)(hdr + 1);
+
+	dent = kzalloc(sizeof(*dent), GFP_KERNEL);
+	if (!dent)
+		return -ENOMEM;
+
+	dent->handle = dsmas->dsmad_handle;
+	dent->dpa_range.start = le64_to_cpu((__force __le64)dsmas->dpa_base_address);
+	dent->dpa_range.end = le64_to_cpu((__force __le64)dsmas->dpa_base_address) +
+			      le64_to_cpu((__force __le64)dsmas->dpa_length) - 1;
+
+	rc = xa_insert(dsmas_xa, dent->handle, dent, GFP_KERNEL);
+	if (rc) {
+		kfree(dent);
+		return rc;
+	}
+
+	return 0;
+}
+
+static int cxl_cdat_endpoint_process(struct cxl_port *port,
+				     struct xarray *dsmas_xa)
+{
+	return cdat_table_parse(ACPI_CDAT_TYPE_DSMAS, cdat_dsmas_handler,
+				dsmas_xa, port->cdat.table);
+}
+
+static void discard_dsmas(struct xarray *xa)
+{
+	unsigned long index;
+	void *ent;
+
+	xa_for_each(xa, index, ent) {
+		xa_erase(xa, index);
+		kfree(ent);
+	}
+	xa_destroy(xa);
+}
+DEFINE_FREE(dsmas, struct xarray *, if (_T) discard_dsmas(_T))
+
+void cxl_endpoint_parse_cdat(struct cxl_port *port)
+{
+	struct xarray __dsmas_xa;
+	struct xarray *dsmas_xa __free(dsmas) = &__dsmas_xa;
+	int rc;
+
+	xa_init(&__dsmas_xa);
+	if (!port->cdat.table)
+		return;
+
+	rc = cxl_cdat_endpoint_process(port, dsmas_xa);
+	if (rc < 0) {
+		dev_dbg(&port->dev, "Failed to parse CDAT: %d\n", rc);
+		return;
+	}
+
+	/* Performance data processing */
+}
+EXPORT_SYMBOL_NS_GPL(cxl_endpoint_parse_cdat, CXL);
+
+MODULE_IMPORT_NS(CXL);