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From:   Ira Weiny <ira.weiny@intel.com>
Date:   Tue, 17 Jan 2023 21:53:36 -0800
Subject: [PATCH v7 1/8] cxl/mem: Read, trace, and clear events on driver load
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Message-Id: <20221216-cxl-ev-log-v7-1-2316a5c8f7d8@intel.com>
References: <20221216-cxl-ev-log-v7-0-2316a5c8f7d8@intel.com>
In-Reply-To: <20221216-cxl-ev-log-v7-0-2316a5c8f7d8@intel.com>
To:     Dan Williams <dan.j.williams@intel.com>
Cc:     Bjorn Helgaas <bhelgaas@google.com>,
        Alison Schofield <alison.schofield@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Ben Widawsky <bwidawsk@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-acpi@vger.kernel.org, linux-cxl@vger.kernel.org
Precedence: bulk

CXL devices have multiple event logs which can be queried for CXL event
records.  Devices are required to support the storage of at least one
event record in each event log type.

Devices track event log overflow by incrementing a counter and tracking
the time of the first and last overflow event seen.

Software queries events via the Get Event Record mailbox command; CXL
rev 3.0 section 8.2.9.2.2 and clears events via CXL rev 3.0 section
8.2.9.2.3 Clear Event Records mailbox command.

If the result of negotiating CXL Error Reporting Control is OS control,
read and clear all event logs on driver load.

Ensure a clean slate of events by reading and clearing the events on
driver load.

The status register is not used because a device may continue to trigger
events and the only requirement is to empty the log at least once.  This
allows for the required transition from empty to non-empty for interrupt
generation.  Handling of interrupts is in a follow on patch.

The device can return up to 1MB worth of event records per query.
Allocate a shared large buffer to handle the max number of records based
on the mailbox payload size.

This patch traces a raw event record and leaves specific event record
type tracing to subsequent patches.  Macros are created to aid in
tracing the common CXL Event header fields.

Each record is cleared explicitly.  A clear all bit is specified but is
only valid when the log overflows.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes in v7:
        Jonathan
		Picked up Jonathans review
		Shorten dev error line lengths
		Return error from devm_add_action_or_reset
	Jonathan/Dan
		Make struct cxl_mbox_clear_event_payload a dynamic struct
		Clarify meaning of CXL_CLEAR_EVENT_MAX_HANDLES
	Jonathan
		Only allocate buffer if native cxl error is true
---
 drivers/cxl/core/mbox.c  | 148 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/core/trace.h | 120 ++++++++++++++++++++++++++++++++++++++
 drivers/cxl/cxl.h        |  12 ++++
 drivers/cxl/cxlmem.h     |  79 +++++++++++++++++++++++++
 drivers/cxl/pci.c        |  42 ++++++++++++++
 5 files changed, 401 insertions(+)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index b03fba212799..c329c1e67a2c 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -8,6 +8,7 @@
 #include <cxl.h>
 
 #include "core.h"
+#include "trace.h"
 
 static bool cxl_raw_allow_all;
 
@@ -717,6 +718,152 @@ int cxl_enumerate_cmds(struct cxl_dev_state *cxlds)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_enumerate_cmds, CXL);
 
+static int cxl_clear_event_record(struct cxl_dev_state *cxlds,
+				  enum cxl_event_log_type log,
+				  struct cxl_get_event_payload *get_pl)
+{
+	struct cxl_mbox_clear_event_payload *payload;
+	u16 total = le16_to_cpu(get_pl->record_count);
+	u8 max_handles = CXL_CLEAR_EVENT_MAX_HANDLES;
+	size_t pl_size = struct_size(payload, handles, max_handles);
+	struct cxl_mbox_cmd mbox_cmd;
+	u16 cnt;
+	int rc = 0;
+	int i;
+
+	/* Payload size may limit the max handles */
+	if (pl_size > cxlds->payload_size) {
+		max_handles = (cxlds->payload_size - sizeof(*payload)) /
+				sizeof(__le16);
+		pl_size = struct_size(payload, handles, max_handles);
+	}
+
+	payload = kvzalloc(pl_size, GFP_KERNEL);
+	if (!payload)
+		return -ENOMEM;
+
+	*payload = (struct cxl_mbox_clear_event_payload) {
+		.event_log = log,
+	};
+
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_CLEAR_EVENT_RECORD,
+		.payload_in = payload,
+		.size_in = pl_size,
+	};
+
+	/*
+	 * Clear Event Records uses u8 for the handle cnt while Get Event
+	 * Record can return up to 0xffff records.
+	 */
+	i = 0;
+	for (cnt = 0; cnt < total; cnt++) {
+		payload->handles[i++] = get_pl->records[cnt].hdr.handle;
+		dev_dbg(cxlds->dev, "Event log '%d': Clearing %u\n",
+			log, le16_to_cpu(payload->handles[i]));
+
+		if (i == max_handles) {
+			payload->nr_recs = i;
+			rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
+			if (rc)
+				goto free_pl;
+			i = 0;
+		}
+	}
+
+	/* Clear what is left if any */
+	if (i) {
+		payload->nr_recs = i;
+		mbox_cmd.size_in = struct_size(payload, handles, i);
+		rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
+		if (rc)
+			goto free_pl;
+	}
+
+free_pl:
+	kvfree(payload);
+	return rc;
+}
+
+static void cxl_mem_get_records_log(struct cxl_dev_state *cxlds,
+				    enum cxl_event_log_type type)
+{
+	struct cxl_get_event_payload *payload;
+	struct cxl_mbox_cmd mbox_cmd;
+	u8 log_type = type;
+	u16 nr_rec;
+
+	mutex_lock(&cxlds->event.log_lock);
+	payload = cxlds->event.buf;
+
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_GET_EVENT_RECORD,
+		.payload_in = &log_type,
+		.size_in = sizeof(log_type),
+		.payload_out = payload,
+		.size_out = cxlds->payload_size,
+		.min_out = struct_size(payload, records, 0),
+	};
+
+	do {
+		int rc, i;
+
+		rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
+		if (rc) {
+			dev_err_ratelimited(cxlds->dev,
+				"Event log '%d': Failed to query event records : %d",
+				type, rc);
+			break;
+		}
+
+		nr_rec = le16_to_cpu(payload->record_count);
+		if (!nr_rec)
+			break;
+
+		for (i = 0; i < nr_rec; i++)
+			trace_cxl_generic_event(cxlds->dev, type,
+						&payload->records[i]);
+
+		if (payload->flags & CXL_GET_EVENT_FLAG_OVERFLOW)
+			trace_cxl_overflow(cxlds->dev, type, payload);
+
+		rc = cxl_clear_event_record(cxlds, type, payload);
+		if (rc) {
+			dev_err_ratelimited(cxlds->dev,
+				"Event log '%d': Failed to clear events : %d",
+				type, rc);
+			break;
+		}
+	} while (nr_rec);
+
+	mutex_unlock(&cxlds->event.log_lock);
+}
+
+/**
+ * cxl_mem_get_event_records - Get Event Records from the device
+ * @cxlds: The device data for the operation
+ *
+ * Retrieve all event records available on the device, report them as trace
+ * events, and clear them.
+ *
+ * See CXL rev 3.0 @8.2.9.2.2 Get Event Records
+ * See CXL rev 3.0 @8.2.9.2.3 Clear Event Records
+ */
+void cxl_mem_get_event_records(struct cxl_dev_state *cxlds, u32 status)
+{
+	dev_dbg(cxlds->dev, "Reading event logs: %x\n", status);
+
+	if (status & CXLDEV_EVENT_STATUS_FATAL)
+		cxl_mem_get_records_log(cxlds, CXL_EVENT_TYPE_FATAL);
+	if (status & CXLDEV_EVENT_STATUS_FAIL)
+		cxl_mem_get_records_log(cxlds, CXL_EVENT_TYPE_FAIL);
+	if (status & CXLDEV_EVENT_STATUS_WARN)
+		cxl_mem_get_records_log(cxlds, CXL_EVENT_TYPE_WARN);
+	if (status & CXLDEV_EVENT_STATUS_INFO)
+		cxl_mem_get_records_log(cxlds, CXL_EVENT_TYPE_INFO);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_mem_get_event_records, CXL);
+
 /**
  * cxl_mem_get_partition_info - Get partition info
  * @cxlds: The device data for the operation
@@ -868,6 +1015,7 @@ struct cxl_dev_state *cxl_dev_state_create(struct device *dev)
 	}
 
 	mutex_init(&cxlds->mbox_mutex);
+	mutex_init(&cxlds->event.log_lock);
 	cxlds->dev = dev;
 
 	return cxlds;
diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
index 20ca2fe2ca8e..6898212fcb47 100644
--- a/drivers/cxl/core/trace.h
+++ b/drivers/cxl/core/trace.h
@@ -6,7 +6,9 @@
 #if !defined(_CXL_EVENTS_H) || defined(TRACE_HEADER_MULTI_READ)
 #define _CXL_EVENTS_H
 
+#include <asm-generic/unaligned.h>
 #include <cxl.h>
+#include <cxlmem.h>
 #include <linux/tracepoint.h>
 
 #define CXL_RAS_UC_CACHE_DATA_PARITY	BIT(0)
@@ -103,6 +105,124 @@ TRACE_EVENT(cxl_aer_correctable_error,
 	)
 );
 
+#include <linux/tracepoint.h>
+
+#define cxl_event_log_type_str(type)				\
+	__print_symbolic(type,					\
+		{ CXL_EVENT_TYPE_INFO, "Informational" },	\
+		{ CXL_EVENT_TYPE_WARN, "Warning" },		\
+		{ CXL_EVENT_TYPE_FAIL, "Failure" },		\
+		{ CXL_EVENT_TYPE_FATAL, "Fatal" })
+
+TRACE_EVENT(cxl_overflow,
+
+	TP_PROTO(const struct device *dev, enum cxl_event_log_type log,
+		 struct cxl_get_event_payload *payload),
+
+	TP_ARGS(dev, log, payload),
+
+	TP_STRUCT__entry(
+		__string(dev_name, dev_name(dev))
+		__field(int, log)
+		__field(u64, first_ts)
+		__field(u64, last_ts)
+		__field(u16, count)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev_name, dev_name(dev));
+		__entry->log = log;
+		__entry->count = le16_to_cpu(payload->overflow_err_count);
+		__entry->first_ts = le64_to_cpu(payload->first_overflow_timestamp);
+		__entry->last_ts = le64_to_cpu(payload->last_overflow_timestamp);
+	),
+
+	TP_printk("%s: log=%s : %u records from %llu to %llu",
+		__get_str(dev_name), cxl_event_log_type_str(__entry->log),
+		__entry->count, __entry->first_ts, __entry->last_ts)
+
+);
+
+/*
+ * Common Event Record Format
+ * CXL 3.0 section 8.2.9.2.1; Table 8-42
+ */
+#define CXL_EVENT_RECORD_FLAG_PERMANENT		BIT(2)
+#define CXL_EVENT_RECORD_FLAG_MAINT_NEEDED	BIT(3)
+#define CXL_EVENT_RECORD_FLAG_PERF_DEGRADED	BIT(4)
+#define CXL_EVENT_RECORD_FLAG_HW_REPLACE	BIT(5)
+#define show_hdr_flags(flags)	__print_flags(flags, " | ",			   \
+	{ CXL_EVENT_RECORD_FLAG_PERMANENT,	"PERMANENT_CONDITION"		}, \
+	{ CXL_EVENT_RECORD_FLAG_MAINT_NEEDED,	"MAINTENANCE_NEEDED"		}, \
+	{ CXL_EVENT_RECORD_FLAG_PERF_DEGRADED,	"PERFORMANCE_DEGRADED"		}, \
+	{ CXL_EVENT_RECORD_FLAG_HW_REPLACE,	"HARDWARE_REPLACEMENT_NEEDED"	}  \
+)
+
+/*
+ * Define macros for the common header of each CXL event.
+ *
+ * Tracepoints using these macros must do 3 things:
+ *
+ *	1) Add CXL_EVT_TP_entry to TP_STRUCT__entry
+ *	2) Use CXL_EVT_TP_fast_assign within TP_fast_assign;
+ *	   pass the dev, log, and CXL event header
+ *	3) Use CXL_EVT_TP_printk() instead of TP_printk()
+ *
+ * See the generic_event tracepoint as an example.
+ */
+#define CXL_EVT_TP_entry					\
+	__string(dev_name, dev_name(dev))			\
+	__field(int, log)					\
+	__field_struct(uuid_t, hdr_uuid)			\
+	__field(u32, hdr_flags)					\
+	__field(u16, hdr_handle)				\
+	__field(u16, hdr_related_handle)			\
+	__field(u64, hdr_timestamp)				\
+	__field(u8, hdr_length)					\
+	__field(u8, hdr_maint_op_class)
+
+#define CXL_EVT_TP_fast_assign(dev, l, hdr)					\
+	__assign_str(dev_name, dev_name(dev));					\
+	__entry->log = (l);							\
+	memcpy(&__entry->hdr_uuid, &(hdr).id, sizeof(uuid_t));			\
+	__entry->hdr_length = (hdr).length;					\
+	__entry->hdr_flags = get_unaligned_le24((hdr).flags);			\
+	__entry->hdr_handle = le16_to_cpu((hdr).handle);			\
+	__entry->hdr_related_handle = le16_to_cpu((hdr).related_handle);	\
+	__entry->hdr_timestamp = le64_to_cpu((hdr).timestamp);			\
+	__entry->hdr_maint_op_class = (hdr).maint_op_class
+
+#define CXL_EVT_TP_printk(fmt, ...) \
+	TP_printk("%s log=%s : time=%llu uuid=%pUb len=%d flags='%s' "		\
+		"handle=%x related_handle=%x maint_op_class=%u"			\
+		" : " fmt,							\
+		__get_str(dev_name), cxl_event_log_type_str(__entry->log),	\
+		__entry->hdr_timestamp, &__entry->hdr_uuid, __entry->hdr_length,\
+		show_hdr_flags(__entry->hdr_flags), __entry->hdr_handle,	\
+		__entry->hdr_related_handle, __entry->hdr_maint_op_class,	\
+		##__VA_ARGS__)
+
+TRACE_EVENT(cxl_generic_event,
+
+	TP_PROTO(const struct device *dev, enum cxl_event_log_type log,
+		 struct cxl_event_record_raw *rec),
+
+	TP_ARGS(dev, log, rec),
+
+	TP_STRUCT__entry(
+		CXL_EVT_TP_entry
+		__array(u8, data, CXL_EVENT_RECORD_DATA_LENGTH)
+	),
+
+	TP_fast_assign(
+		CXL_EVT_TP_fast_assign(dev, log, rec->hdr);
+		memcpy(__entry->data, &rec->data, CXL_EVENT_RECORD_DATA_LENGTH);
+	),
+
+	CXL_EVT_TP_printk("%s",
+		__print_hex(__entry->data, CXL_EVENT_RECORD_DATA_LENGTH))
+);
+
 #endif /* _CXL_EVENTS_H */
 
 #define TRACE_INCLUDE_FILE trace
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index aa3af3bb73b2..5974d1082210 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -156,6 +156,18 @@ static inline int ways_to_eiw(unsigned int ways, u8 *eiw)
 #define CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX 0x3
 #define CXLDEV_CAP_CAP_ID_MEMDEV 0x4000
 
+/* CXL 3.0 8.2.8.3.1 Event Status Register */
+#define CXLDEV_DEV_EVENT_STATUS_OFFSET		0x00
+#define CXLDEV_EVENT_STATUS_INFO		BIT(0)
+#define CXLDEV_EVENT_STATUS_WARN		BIT(1)
+#define CXLDEV_EVENT_STATUS_FAIL		BIT(2)
+#define CXLDEV_EVENT_STATUS_FATAL		BIT(3)
+
+#define CXLDEV_EVENT_STATUS_ALL (CXLDEV_EVENT_STATUS_INFO |	\
+				 CXLDEV_EVENT_STATUS_WARN |	\
+				 CXLDEV_EVENT_STATUS_FAIL |	\
+				 CXLDEV_EVENT_STATUS_FATAL)
+
 /* CXL 2.0 8.2.8.4 Mailbox Registers */
 #define CXLDEV_MBOX_CAPS_OFFSET 0x00
 #define   CXLDEV_MBOX_CAP_PAYLOAD_SIZE_MASK GENMASK(4, 0)
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index ab138004f644..0f272206e294 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -4,6 +4,7 @@
 #define __CXL_MEM_H__
 #include <uapi/linux/cxl_mem.h>
 #include <linux/cdev.h>
+#include <linux/uuid.h>
 #include "cxl.h"
 
 /* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
@@ -193,6 +194,17 @@ struct cxl_endpoint_dvsec_info {
 	struct range dvsec_range[2];
 };
 
+/**
+ * struct cxl_event_state - Event log driver state
+ *
+ * @event_buf: Buffer to receive event data
+ * @event_log_lock: Serialize event_buf and log use
+ */
+struct cxl_event_state {
+	struct cxl_get_event_payload *buf;
+	struct mutex log_lock;
+};
+
 /**
  * struct cxl_dev_state - The driver device state
  *
@@ -266,12 +278,16 @@ struct cxl_dev_state {
 
 	struct xarray doe_mbs;
 
+	struct cxl_event_state event;
+
 	int (*mbox_send)(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *cmd);
 };
 
 enum cxl_opcode {
 	CXL_MBOX_OP_INVALID		= 0x0000,
 	CXL_MBOX_OP_RAW			= CXL_MBOX_OP_INVALID,
+	CXL_MBOX_OP_GET_EVENT_RECORD	= 0x0100,
+	CXL_MBOX_OP_CLEAR_EVENT_RECORD	= 0x0101,
 	CXL_MBOX_OP_GET_FW_INFO		= 0x0200,
 	CXL_MBOX_OP_ACTIVATE_FW		= 0x0202,
 	CXL_MBOX_OP_GET_SUPPORTED_LOGS	= 0x0400,
@@ -347,6 +363,68 @@ struct cxl_mbox_identify {
 	u8 qos_telemetry_caps;
 } __packed;
 
+/*
+ * Common Event Record Format
+ * CXL rev 3.0 section 8.2.9.2.1; Table 8-42
+ */
+struct cxl_event_record_hdr {
+	uuid_t id;
+	u8 length;
+	u8 flags[3];
+	__le16 handle;
+	__le16 related_handle;
+	__le64 timestamp;
+	u8 maint_op_class;
+	u8 reserved[15];
+} __packed;
+
+#define CXL_EVENT_RECORD_DATA_LENGTH 0x50
+struct cxl_event_record_raw {
+	struct cxl_event_record_hdr hdr;
+	u8 data[CXL_EVENT_RECORD_DATA_LENGTH];
+} __packed;
+
+/*
+ * Get Event Records output payload
+ * CXL rev 3.0 section 8.2.9.2.2; Table 8-50
+ */
+#define CXL_GET_EVENT_FLAG_OVERFLOW		BIT(0)
+#define CXL_GET_EVENT_FLAG_MORE_RECORDS		BIT(1)
+struct cxl_get_event_payload {
+	u8 flags;
+	u8 reserved1;
+	__le16 overflow_err_count;
+	__le64 first_overflow_timestamp;
+	__le64 last_overflow_timestamp;
+	__le16 record_count;
+	u8 reserved2[10];
+	struct cxl_event_record_raw records[];
+} __packed;
+
+/*
+ * CXL rev 3.0 section 8.2.9.2.2; Table 8-49
+ */
+enum cxl_event_log_type {
+	CXL_EVENT_TYPE_INFO = 0x00,
+	CXL_EVENT_TYPE_WARN,
+	CXL_EVENT_TYPE_FAIL,
+	CXL_EVENT_TYPE_FATAL,
+	CXL_EVENT_TYPE_MAX
+};
+
+/*
+ * Clear Event Records input payload
+ * CXL rev 3.0 section 8.2.9.2.3; Table 8-51
+ */
+struct cxl_mbox_clear_event_payload {
+	u8 event_log;		/* enum cxl_event_log_type */
+	u8 clear_flags;
+	u8 nr_recs;
+	u8 reserved[3];
+	__le16 handles[];
+} __packed;
+#define CXL_CLEAR_EVENT_MAX_HANDLES 0xff /* max based on nr_recs */
+
 struct cxl_mbox_get_partition_info {
 	__le64 active_volatile_cap;
 	__le64 active_persistent_cap;
@@ -441,6 +519,7 @@ int cxl_mem_create_range_info(struct cxl_dev_state *cxlds);
 struct cxl_dev_state *cxl_dev_state_create(struct device *dev);
 void set_exclusive_cxl_commands(struct cxl_dev_state *cxlds, unsigned long *cmds);
 void clear_exclusive_cxl_commands(struct cxl_dev_state *cxlds, unsigned long *cmds);
+void cxl_mem_get_event_records(struct cxl_dev_state *cxlds, u32 status);
 #ifdef CONFIG_CXL_SUSPEND
 void cxl_mem_active_inc(void);
 void cxl_mem_active_dec(void);
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 3a66aadb4df0..0fd7742ee70c 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -417,8 +417,39 @@ static void disable_aer(void *pdev)
 	pci_disable_pcie_error_reporting(pdev);
 }
 
+static void cxl_mem_free_event_buffer(void *buf)
+{
+	kvfree(buf);
+}
+
+/*
+ * There is a single buffer for reading event logs from the mailbox.  All logs
+ * share this buffer protected by the cxlds->event_log_lock.
+ */
+static int cxl_mem_alloc_event_buf(struct cxl_dev_state *cxlds)
+{
+	struct cxl_get_event_payload *buf;
+	int rc;
+
+	dev_dbg(cxlds->dev, "Allocating event buffer size %zu\n",
+		cxlds->payload_size);
+
+	buf = kvmalloc(cxlds->payload_size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	rc = devm_add_action_or_reset(cxlds->dev, cxl_mem_free_event_buffer,
+				      buf);
+	if (rc)
+		return rc;
+
+	cxlds->event.buf = buf;
+	return 0;
+}
+
 static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
+	struct pci_host_bridge *host_bridge = pci_find_host_bridge(pdev->bus);
 	struct cxl_register_map map;
 	struct cxl_memdev *cxlmd;
 	struct cxl_dev_state *cxlds;
@@ -494,6 +525,17 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (IS_ERR(cxlmd))
 		return PTR_ERR(cxlmd);
 
+	/*
+	 * When BIOS maintains CXL error reporting control, it will process
+	 * event records.  Only one agent can do so.
+	 */
+	if (host_bridge->native_cxl_error) {
+		rc = cxl_mem_alloc_event_buf(cxlds);
+		if (rc)
+			return rc;
+		cxl_mem_get_event_records(cxlds, CXLDEV_EVENT_STATUS_ALL);
+	}
+
 	if (cxlds->regs.ras) {
 		pci_enable_pcie_error_reporting(pdev);
 		rc = devm_add_action_or_reset(&pdev->dev, disable_aer, pdev);

-- 
2.39.0