diff mbox series

[v4,04/23] cxl: Add common helpers for cdat parsing

Message ID 168193568543.1178687.3067575213689202382.stgit@djiang5-mobl3
State New
Headers show
Series cxl: Add support for QTG ID retrieval for CXL subsystem | expand

Commit Message

Dave Jiang April 19, 2023, 8:21 p.m. UTC 
Add helper functions to parse the CDAT table and provide a callback to
parse the sub-table. Helpers are provided for DSMAS and DSLBIS sub-table
parsing. The code is patterned after the ACPI table parsing helpers.

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

---
v2:
- Use local headers to handle LE instead of ACPI header
- Reduce complexity of parser function. (Jonathan)
- Directly access header type. (Jonathan)
- Simplify header ptr math. (Jonathan)
- Move parsed counter to the correct location. (Jonathan)
- Add LE to host conversion for entry length
---
 drivers/cxl/core/Makefile |    1 
 drivers/cxl/core/cdat.c   |  100 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/cxlpci.h      |   29 +++++++++++++
 3 files changed, 130 insertions(+)
 create mode 100644 drivers/cxl/core/cdat.c

Comments

Dan Williams April 24, 2023, 10:33 p.m. UTC | #1 
Dave Jiang wrote:
> Add helper functions to parse the CDAT table and provide a callback to
> parse the sub-table. Helpers are provided for DSMAS and DSLBIS sub-table
> parsing. The code is patterned after the ACPI table parsing helpers.

It seems a shame that CDAT is so ACPI-like, but can't reuse the ACPI
table parsing infrastructure. Can this not be achieved by modifying some
of the helpers helpers in drivers/acpi/tables.c to take a passed in
@table_header?
Dave Jiang April 25, 2023, 4 p.m. UTC | #2 
On 4/24/23 3:33 PM, Dan Williams wrote:
> Dave Jiang wrote:
>> Add helper functions to parse the CDAT table and provide a callback to
>> parse the sub-table. Helpers are provided for DSMAS and DSLBIS sub-table
>> parsing. The code is patterned after the ACPI table parsing helpers.
> 
> It seems a shame that CDAT is so ACPI-like, but can't reuse the ACPI
> table parsing infrastructure. Can this not be achieved by modifying some
> of the helpers helpers in drivers/acpi/tables.c to take a passed in
> @table_header?

Rafael,
Do you have any issues with adding some endieness support in 
drivers/acpi/tables.c in order to support CDAT parsing by BE hosts? To 
start off with something like below?

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index 7b4680da57d7..e63e2daf151d 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -287,6 +287,12 @@ acpi_get_subtable_type(char *id)
         return ACPI_SUBTABLE_COMMON;
  }

+static unsigned long __init_or_acpilib
+acpi_table_get_length(struct acpi_table_header *hdr)
+{
+       return le32_to_cpu((__force __le32)hdr->length);
+}
+
  static __init_or_acpilib bool has_handler(struct acpi_subtable_proc *proc)
  {
         return proc->handler || proc->handler_arg;
@@ -337,7 +343,8 @@ static int __init_or_acpilib acpi_parse_entries_array(
         int errs = 0;
         int i;

-       table_end = (unsigned long)table_header + table_header->length;
+       table_end = (unsigned long)table_header +
+                   acpi_table_get_length(table_header);

         /* Parse all entries looking for a match. */
Dan Williams April 27, 2023, 12:09 a.m. UTC | #3 
Dave Jiang wrote:
> 
> 
> On 4/24/23 3:33 PM, Dan Williams wrote:
> > Dave Jiang wrote:
> >> Add helper functions to parse the CDAT table and provide a callback to
> >> parse the sub-table. Helpers are provided for DSMAS and DSLBIS sub-table
> >> parsing. The code is patterned after the ACPI table parsing helpers.
> > 
> > It seems a shame that CDAT is so ACPI-like, but can't reuse the ACPI
> > table parsing infrastructure. Can this not be achieved by modifying some
> > of the helpers helpers in drivers/acpi/tables.c to take a passed in
> > @table_header?
> 
> Rafael,
> Do you have any issues with adding some endieness support in 
> drivers/acpi/tables.c in order to support CDAT parsing by BE hosts? To 
> start off with something like below?

Some additional background, recall that CDAT is an ACPI-like data
structure that lives on endpoint CXL devices to describe the access
characteristics of the device's memory similar to SRAT+HMAT for
host-memory. Unlike ACPI that is guaranteed to be deployed on a
little-endian host-cpu, a big-endian host might also encounter CXL
endpoints.

This reuse ends up at ~50 lines and duplication ends up at ~100 lines.
Not a huge win, but a win nonetheless.

> 
> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> index 7b4680da57d7..e63e2daf151d 100644
> --- a/drivers/acpi/tables.c
> +++ b/drivers/acpi/tables.c
> @@ -287,6 +287,12 @@ acpi_get_subtable_type(char *id)
>          return ACPI_SUBTABLE_COMMON;
>   }
> 
> +static unsigned long __init_or_acpilib
> +acpi_table_get_length(struct acpi_table_header *hdr)
> +{
> +       return le32_to_cpu((__force __le32)hdr->length);
> +}
> +
>   static __init_or_acpilib bool has_handler(struct acpi_subtable_proc *proc)
>   {
>          return proc->handler || proc->handler_arg;
> @@ -337,7 +343,8 @@ static int __init_or_acpilib acpi_parse_entries_array(
>          int errs = 0;
>          int i;
> 
> -       table_end = (unsigned long)table_header + table_header->length;
> +       table_end = (unsigned long)table_header +
> +                   acpi_table_get_length(table_header);
> 
>          /* Parse all entries looking for a match. */
>
diff mbox series

Patch

diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index ca4ae31d8f57..867a8014b462 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -12,5 +12,6 @@  cxl_core-y += memdev.o
 cxl_core-y += mbox.o
 cxl_core-y += pci.o
 cxl_core-y += hdm.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..210f4499bddb
--- /dev/null
+++ b/drivers/cxl/core/cdat.c
@@ -0,0 +1,100 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2023 Intel Corporation. All rights reserved. */
+#include "cxlpci.h"
+#include "cxl.h"
+
+static bool has_handler(struct cdat_subtable_proc *proc)
+{
+	return proc->handler;
+}
+
+static int call_handler(struct cdat_subtable_proc *proc,
+			struct cdat_subtable_entry *ent)
+{
+	if (has_handler(proc))
+		return proc->handler(ent->hdr, proc->arg);
+	return -EINVAL;
+}
+
+static bool cdat_is_subtable_match(struct cdat_subtable_entry *ent)
+{
+	return ent->hdr->type == ent->type;
+}
+
+static int cdat_table_parse_entries(enum cdat_type type,
+				    struct cdat_header *table_header,
+				    struct cdat_subtable_proc *proc)
+{
+	unsigned long table_end, entry_len;
+	struct cdat_subtable_entry entry;
+	int count = 0;
+	int rc;
+
+	if (!has_handler(proc))
+		return -EINVAL;
+
+	table_end = (unsigned long)table_header + table_header->length;
+
+	if (type >= CDAT_TYPE_RESERVED)
+		return -EINVAL;
+
+	entry.type = type;
+	entry.hdr = (struct cdat_entry_header *)(table_header + 1);
+
+	while ((unsigned long)entry.hdr < table_end) {
+		entry_len = le16_to_cpu(entry.hdr->length);
+
+		if ((unsigned long)entry.hdr + entry_len > table_end)
+			return -EINVAL;
+
+		if (entry_len == 0)
+			return -EINVAL;
+
+		if (cdat_is_subtable_match(&entry)) {
+			rc = call_handler(proc, &entry);
+			if (rc)
+				return rc;
+			count++;
+		}
+
+		entry.hdr = (struct cdat_entry_header *)((unsigned long)entry.hdr + entry_len);
+	}
+
+	return count;
+}
+
+int cdat_table_parse_dsmas(struct cdat_header *table,
+			   cdat_tbl_entry_handler handler, void *arg)
+{
+	struct cdat_subtable_proc proc = {
+		.handler	= handler,
+		.arg		= arg,
+	};
+
+	return cdat_table_parse_entries(CDAT_TYPE_DSMAS, table, &proc);
+}
+EXPORT_SYMBOL_NS_GPL(cdat_table_parse_dsmas, CXL);
+
+int cdat_table_parse_dslbis(struct cdat_header *table,
+			    cdat_tbl_entry_handler handler, void *arg)
+{
+	struct cdat_subtable_proc proc = {
+		.handler	= handler,
+		.arg		= arg,
+	};
+
+	return cdat_table_parse_entries(CDAT_TYPE_DSLBIS, table, &proc);
+}
+EXPORT_SYMBOL_NS_GPL(cdat_table_parse_dslbis, CXL);
+
+int cdat_table_parse_sslbis(struct cdat_header *table,
+			    cdat_tbl_entry_handler handler, void *arg)
+{
+	struct cdat_subtable_proc proc = {
+		.handler	= handler,
+		.arg		= arg,
+	};
+
+	return cdat_table_parse_entries(CDAT_TYPE_SSLBIS, table, &proc);
+}
+EXPORT_SYMBOL_NS_GPL(cdat_table_parse_sslbis, CXL);
diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
index 0465ef963cd6..45e2f2bf5ef8 100644
--- a/drivers/cxl/cxlpci.h
+++ b/drivers/cxl/cxlpci.h
@@ -76,12 +76,34 @@  struct cdat_header {
 	__le32 sequence;
 } __packed;
 
+enum cdat_type {
+	CDAT_TYPE_DSMAS = 0,
+	CDAT_TYPE_DSLBIS,
+	CDAT_TYPE_DSMSCIS,
+	CDAT_TYPE_DSIS,
+	CDAT_TYPE_DSEMTS,
+	CDAT_TYPE_SSLBIS,
+	CDAT_TYPE_RESERVED
+};
+
 struct cdat_entry_header {
 	u8 type;
 	u8 reserved;
 	__le16 length;
 } __packed;
 
+typedef int (*cdat_tbl_entry_handler)(struct cdat_entry_header *header, void *arg);
+
+struct cdat_subtable_proc {
+	cdat_tbl_entry_handler handler;
+	void *arg;
+};
+
+struct cdat_subtable_entry {
+	struct cdat_entry_header *hdr;
+	enum cdat_type type;
+};
+
 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,
@@ -90,4 +112,11 @@  void read_cdat_data(struct cxl_port *port);
 void cxl_cor_error_detected(struct pci_dev *pdev);
 pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
 				    pci_channel_state_t state);
+
+#define cdat_table_parse(x) \
+int cdat_table_parse_##x(struct cdat_header *table, \
+			 cdat_tbl_entry_handler handler, void *arg)
+cdat_table_parse(dsmas);
+cdat_table_parse(dslbis);
+cdat_table_parse(sslbis);
 #endif /* __CXL_PCI_H__ */