[PATCH v3 3/3] ACPI: APEI: GHES: Add NVIDIA vendor CPER record handler

Add support for decoding NVIDIA-specific CPER sections delivered via
the APEI GHES vendor record notifier chain. NVIDIA hardware generates
vendor-specific CPER sections containing error signatures and diagnostic
register dumps. This implementation registers a notifier_block with the
GHES vendor record notifier and decodes these sections, printing error
details via dev_info().

The driver binds to ACPI device NVDA2012, present on NVIDIA server
platforms. The NVIDIA CPER section contains a fixed header with error
metadata (signature, error type, severity, socket) followed by
variable-length register address-value pairs for hardware diagnostics.

This work is based on libcper [0].

Example output:
nvidia-ghes NVDA2012:00: NVIDIA CPER section, error_data_length: 544
nvidia-ghes NVDA2012:00: signature: CMET-INFO
nvidia-ghes NVDA2012:00: error_type: 0
nvidia-ghes NVDA2012:00: error_instance: 0
nvidia-ghes NVDA2012:00: severity: 3
nvidia-ghes NVDA2012:00: socket: 0
nvidia-ghes NVDA2012:00: number_regs: 32
nvidia-ghes NVDA2012:00: instance_base: 0x0000000000000000
nvidia-ghes NVDA2012:00: register[0]: address=0x8000000100000000 value=0x0000000100000000

[0] https://github.com/openbmc/libcper/commit/683e055061ce
Cc: Shiju Jose <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Signed-off-by: Kai-Heng Feng <[email protected]>
---
v3:
  - NVIDIA_GHES to GHES_NVIDIA.
  - Better error handling in probe()
  - "int i" in for loop.
v2:
  - Use right headers.
  - Use embedded struct and __counted_by.
  - Drop __packed.
  - Remove unecessary casts. 
  - Use * in sizeof().
  - Use devm_kmalloc() and struct assignment.
  - Use dev_err_probe and new devm helper.

 MAINTAINERS                     |   6 ++
 drivers/acpi/apei/Kconfig       |  14 +++
 drivers/acpi/apei/Makefile      |   1 +
 drivers/acpi/apei/ghes-nvidia.c | 149 ++++++++++++++++++++++++++++++++
 4 files changed, 170 insertions(+)
 create mode 100644 drivers/acpi/apei/ghes-nvidia.c

diff --git a/MAINTAINERS b/MAINTAINERS
index c3fe46d7c4bc..94608f8e247e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18919,6 +18919,12 @@ S:	Maintained
 F:	drivers/video/fbdev/nvidia/
 F:	drivers/video/fbdev/riva/
 
+NVIDIA GHES VENDOR CPER RECORD HANDLER
+M:	Kai-Heng Feng <[email protected]>
+L:	[email protected]
+S:	Maintained
+F:	drivers/acpi/apei/nvidia-ghes.c
+
 NVIDIA VRS RTC DRIVER
 M:	Shubhi Garg <[email protected]>
 L:	[email protected]
diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
index 070c07d68dfb..428458c623f0 100644
--- a/drivers/acpi/apei/Kconfig
+++ b/drivers/acpi/apei/Kconfig
@@ -74,6 +74,20 @@ config ACPI_APEI_EINJ_CXL
 
 	  If unsure say 'n'
 
+config ACPI_APEI_GHES_NVIDIA
+	tristate "NVIDIA GHES vendor record handler"
+	depends on ACPI_APEI_GHES
+	help
+	  Support for decoding NVIDIA-specific CPER sections delivered via
+	  the APEI GHES vendor record notifier chain. Registers a handler
+	  for the NVIDIA section GUID and logs error signatures, severity,
+	  socket, and diagnostic register address-value pairs.
+
+	  Enable on NVIDIA server platforms (e.g. DGX, HGX) that expose
+	  ACPI device NVDA2012 in their firmware tables.
+
+	  If unsure, say N.
+
 config ACPI_APEI_ERST_DEBUG
 	tristate "APEI Error Record Serialization Table (ERST) Debug Support"
 	depends on ACPI_APEI
diff --git a/drivers/acpi/apei/Makefile b/drivers/acpi/apei/Makefile
index 1a0b85923cd4..66588d6be56f 100644
--- a/drivers/acpi/apei/Makefile
+++ b/drivers/acpi/apei/Makefile
@@ -10,5 +10,6 @@ obj-$(CONFIG_ACPI_APEI_EINJ)	+= einj.o
 einj-y				:= einj-core.o
 einj-$(CONFIG_ACPI_APEI_EINJ_CXL) += einj-cxl.o
 obj-$(CONFIG_ACPI_APEI_ERST_DEBUG) += erst-dbg.o
+obj-$(CONFIG_ACPI_APEI_GHES_NVIDIA) += ghes-nvidia.o
 
 apei-y := apei-base.o hest.o erst.o bert.o
diff --git a/drivers/acpi/apei/ghes-nvidia.c b/drivers/acpi/apei/ghes-nvidia.c
new file mode 100644
index 000000000000..597275d81de8
--- /dev/null
+++ b/drivers/acpi/apei/ghes-nvidia.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * NVIDIA GHES vendor record handler
+ *
+ * Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ */
+
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/uuid.h>
+#include <acpi/ghes.h>
+
+static const guid_t nvidia_sec_guid =
+	GUID_INIT(0x6d5244f2, 0x2712, 0x11ec,
+		  0xbe, 0xa7, 0xcb, 0x3f, 0xdb, 0x95, 0xc7, 0x86);
+
+struct cper_sec_nvidia {
+	char	signature[16];
+	__le16	error_type;
+	__le16	error_instance;
+	u8	severity;
+	u8	socket;
+	u8	number_regs;
+	u8	reserved;
+	__le64	instance_base;
+	struct {
+		__le64	addr;
+		__le64	val;
+	} regs[] __counted_by(number_regs);
+};
+
+struct nvidia_ghes_private {
+	struct notifier_block	nb;
+	struct device		*dev;
+};
+
+static void nvidia_ghes_print_error(struct device *dev,
+				    const struct cper_sec_nvidia *nvidia_err,
+				    size_t error_data_length, bool fatal)
+{
+	const char *level = fatal ? KERN_ERR : KERN_INFO;
+	size_t min_size;
+
+	dev_printk(level, dev, "signature: %.16s\n", nvidia_err->signature);
+	dev_printk(level, dev, "error_type: %u\n", le16_to_cpu(nvidia_err->error_type));
+	dev_printk(level, dev, "error_instance: %u\n", le16_to_cpu(nvidia_err->error_instance));
+	dev_printk(level, dev, "severity: %u\n", nvidia_err->severity);
+	dev_printk(level, dev, "socket: %u\n", nvidia_err->socket);
+	dev_printk(level, dev, "number_regs: %u\n", nvidia_err->number_regs);
+	dev_printk(level, dev, "instance_base: 0x%016llx\n",
+		   le64_to_cpu(nvidia_err->instance_base));
+
+	if (nvidia_err->number_regs == 0)
+		return;
+
+	/*
+	 * Validate that all registers fit within error_data_length.
+	 * Each register pair is two little-endian u64s.
+	 */
+	min_size = struct_size(nvidia_err, regs, nvidia_err->number_regs);
+	if (error_data_length < min_size) {
+		dev_err(dev, "Invalid number_regs %u (section size %zu, need %zu)\n",
+			nvidia_err->number_regs, error_data_length, min_size);
+		return;
+	}
+
+	for (int i = 0; i < nvidia_err->number_regs; i++)
+		dev_printk(level, dev, "register[%d]: address=0x%016llx value=0x%016llx\n",
+			   i, le64_to_cpu(nvidia_err->regs[i].addr),
+			   le64_to_cpu(nvidia_err->regs[i].val));
+}
+
+static int nvidia_ghes_notify(struct notifier_block *nb,
+			      unsigned long event, void *data)
+{
+	struct acpi_hest_generic_data *gdata = data;
+	struct nvidia_ghes_private *priv;
+	const struct cper_sec_nvidia *nvidia_err;
+	guid_t sec_guid;
+
+	import_guid(&sec_guid, gdata->section_type);
+	if (!guid_equal(&sec_guid, &nvidia_sec_guid))
+		return NOTIFY_DONE;
+
+	priv = container_of(nb, struct nvidia_ghes_private, nb);
+
+	if (acpi_hest_get_error_length(gdata) < sizeof(*nvidia_err)) {
+		dev_err(priv->dev, "Section too small (%d < %zu)\n",
+			acpi_hest_get_error_length(gdata), sizeof(*nvidia_err));
+		return NOTIFY_OK;
+	}
+
+	nvidia_err = acpi_hest_get_payload(gdata);
+
+	if (event >= GHES_SEV_RECOVERABLE)
+		dev_err(priv->dev, "NVIDIA CPER section, error_data_length: %u\n",
+			acpi_hest_get_error_length(gdata));
+	else
+		dev_info(priv->dev, "NVIDIA CPER section, error_data_length: %u\n",
+			 acpi_hest_get_error_length(gdata));
+
+	nvidia_ghes_print_error(priv->dev, nvidia_err, acpi_hest_get_error_length(gdata),
+				event >= GHES_SEV_RECOVERABLE);
+
+	return NOTIFY_OK;
+}
+
+static int nvidia_ghes_probe(struct platform_device *pdev)
+{
+	struct nvidia_ghes_private *priv;
+	int ret;
+
+	priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	*priv = (struct nvidia_ghes_private) {
+		.nb.notifier_call = nvidia_ghes_notify,
+		.dev = &pdev->dev,
+	};
+
+	ret = devm_ghes_register_vendor_record_notifier(&pdev->dev, &priv->nb);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret,
+				     "Failed to register NVIDIA GHES vendor record notifier\n");
+
+	return 0;
+}
+
+static const struct acpi_device_id nvidia_ghes_acpi_match[] = {
+	{ "NVDA2012" },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, nvidia_ghes_acpi_match);
+
+static struct platform_driver nvidia_ghes_driver = {
+	.driver = {
+		.name = "nvidia-ghes",
+		.acpi_match_table = nvidia_ghes_acpi_match,
+	},
+	.probe = nvidia_ghes_probe,
+};
+module_platform_driver(nvidia_ghes_driver);
+
+MODULE_AUTHOR("Kai-Heng Feng <[email protected]>");
+MODULE_DESCRIPTION("NVIDIA GHES vendor CPER record handler");
+MODULE_LICENSE("GPL");
-- 
2.50.1 (Apple Git-155)