[PATCH v4 16/25] nvdimm/ocxl: Implement the Read Error Log command

["Alastair D'Silva" <alastair@d-silva.org>]

The read error log command extracts information from the controller's
internal error log.

This patch exposes this information in 2 ways:
- During probe, if an error occurs & a log is available, print it to the
  console
- After probe, make the error log available to userspace via an IOCTL.
  Userspace is notified of pending error logs in a later patch
  ("powerpc/powernv/pmem: Forward events to userspace")

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 .../userspace-api/ioctl/ioctl-number.rst      |   1 +
 drivers/nvdimm/ocxl/main.c                    | 240 ++++++++++++++++++
 include/uapi/nvdimm/ocxlpmem.h                |  46 ++++
 3 files changed, 287 insertions(+)
 create mode 100644 include/uapi/nvdimm/ocxlpmem.h

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 9425377615ce..ba0ce7dca643 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -340,6 +340,7 @@ Code  Seq#    Include File                                           Comments
 0xC0  00-0F  linux/usb/iowarrior.h
 0xCA  00-0F  uapi/misc/cxl.h
 0xCA  10-2F  uapi/misc/ocxl.h
+0xCA  30-3F  uapi/nvdimm/ocxlpmem.h                                  OpenCAPI Persistent Memory
 0xCA  80-BF  uapi/scsi/cxlflash_ioctl.h
 0xCB  00-1F                                                          CBM serial IEC bus in development:
                                                                      <mailto:michael.klein@puffin.lb.shuttle.de>
diff --git a/drivers/nvdimm/ocxl/main.c b/drivers/nvdimm/ocxl/main.c
index 9b85fcd3f1c9..e6be0029f658 100644
--- a/drivers/nvdimm/ocxl/main.c
+++ b/drivers/nvdimm/ocxl/main.c
@@ -13,6 +13,7 @@
 #include <linux/fs.h>
 #include <linux/mm_types.h>
 #include <linux/memory_hotplug.h>
+#include <uapi/nvdimm/ocxlpmem.h>
 #include "ocxlpmem.h"
 
 static const struct pci_device_id pci_tbl[] = {
@@ -401,10 +402,190 @@ static int file_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
+/**
+ * error_log_header_parse() - Parse the first 64 bits of the error log command response
+ * @ocxlpmem: the device metadata
+ * @length: out, returns the number of bytes in the response (excluding the 64 bit header)
+ */
+static int error_log_header_parse(struct ocxlpmem *ocxlpmem, u16 *length)
+{
+	int rc;
+	u64 val;
+	u16 data_identifier;
+	u32 data_length;
+
+	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
+				     ocxlpmem->admin_command.data_offset,
+				     OCXL_LITTLE_ENDIAN, &val);
+	if (rc)
+		return rc;
+
+	data_identifier = val >> 48;
+	data_length = val & 0xFFFF;
+
+	if (data_identifier != 0x454C) { // 'EL'
+		dev_err(&ocxlpmem->dev,
+			"Bad data identifier for error log data, expected 'EL', got '%2s' (%#x), data_length=%u\n",
+			(char *)&data_identifier,
+			(unsigned int)data_identifier, data_length);
+		return -EINVAL;
+	}
+
+	*length = data_length;
+	return 0;
+}
+
+static int read_error_log(struct ocxlpmem *ocxlpmem,
+			  struct ioctl_ocxlpmem_error_log *log,
+			  bool buf_is_user)
+{
+	u64 val;
+	u16 user_buf_length;
+	u16 buf_length;
+	u64 *buf = (u64 *)log->buf_ptr;
+	u16 i;
+	int rc;
+
+	if (log->buf_size % 8)
+		return -EINVAL;
+
+	rc = ocxlpmem_chi(ocxlpmem, &val);
+	if (rc)
+		return rc;
+
+	if (!(val & GLOBAL_MMIO_CHI_ELA))
+		return -EAGAIN;
+
+	user_buf_length = log->buf_size;
+
+	mutex_lock(&ocxlpmem->admin_command.lock);
+
+	rc = admin_command_execute(ocxlpmem, ADMIN_COMMAND_ERRLOG);
+	if (rc != STATUS_SUCCESS) {
+		warn_status(ocxlpmem,
+			    "Unexpected status from retrieve error log", rc);
+		goto out;
+	}
+
+	rc = error_log_header_parse(ocxlpmem, &log->buf_size);
+	if (rc)
+		goto out;
+	// log->buf_size now contains the returned buffer size, not the user size
+
+	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
+				     ocxlpmem->admin_command.data_offset + 0x08,
+				     OCXL_LITTLE_ENDIAN, &val);
+	if (rc)
+		goto out;
+
+	log->log_identifier = val >> 32;
+	log->program_reference_code = val & 0xFFFFFFFF;
+
+	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
+				     ocxlpmem->admin_command.data_offset + 0x10,
+				     OCXL_LITTLE_ENDIAN, &val);
+	if (rc)
+		goto out;
+
+	log->error_log_type = val >> 56;
+	log->action_flags = (log->error_log_type == OCXLPMEM_ERROR_LOG_TYPE_GENERAL) ?
+			    (val >> 32) & 0xFFFFFF : 0;
+	log->power_on_seconds = val & 0xFFFFFFFF;
+
+	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
+				     ocxlpmem->admin_command.data_offset + 0x18,
+				     OCXL_LITTLE_ENDIAN, &log->timestamp);
+	if (rc)
+		goto out;
+
+	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
+				     ocxlpmem->admin_command.data_offset + 0x20,
+				     OCXL_LITTLE_ENDIAN, &log->wwid[0]);
+	if (rc)
+		goto out;
+
+	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
+				     ocxlpmem->admin_command.data_offset + 0x28,
+				     OCXL_LITTLE_ENDIAN, &log->wwid[1]);
+	if (rc)
+		goto out;
+
+	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
+				     ocxlpmem->admin_command.data_offset + 0x30,
+				     OCXL_HOST_ENDIAN, (u64 *)log->fw_revision);
+	if (rc)
+		goto out;
+	log->fw_revision[8] = '\0';
+
+	buf_length = (user_buf_length < log->buf_size) ?
+		      user_buf_length : log->buf_size;
+	for (i = 0; i < buf_length / (sizeof(u64)); i++) {
+		rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
+					     ocxlpmem->admin_command.data_offset +
+							i * sizeof(u64),
+					     OCXL_HOST_ENDIAN, &val);
+		if (rc)
+			goto out;
+
+		if (buf_is_user) {
+			if (copy_to_user((u64 __user *)&buf[i], &val,
+					 sizeof(u64))) {
+				rc = -EFAULT;
+				goto out;
+			}
+		} else {
+			buf[i] = val;
+		}
+	}
+
+	rc = admin_response_handled(ocxlpmem);
+	if (rc)
+		goto out;
+
+out:
+	mutex_unlock(&ocxlpmem->admin_command.lock);
+	return rc;
+}
+
+static int ioctl_error_log(struct ocxlpmem *ocxlpmem,
+			   struct ioctl_ocxlpmem_error_log __user *uarg)
+{
+	struct ioctl_ocxlpmem_error_log args;
+	int rc;
+
+	if (copy_from_user(&args, uarg, sizeof(args)))
+		return -EFAULT;
+
+	rc = read_error_log(ocxlpmem, &args, true);
+	if (rc)
+		return rc;
+
+	if (copy_to_user(uarg, &args, sizeof(args)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long file_ioctl(struct file *file, unsigned int cmd, unsigned long args)
+{
+	struct ocxlpmem *ocxlpmem = file->private_data;
+	int rc = -EINVAL;
+
+	switch (cmd) {
+	case IOCTL_OCXLPMEM_ERROR_LOG:
+		rc = ioctl_error_log(ocxlpmem,
+				     (struct ioctl_ocxlpmem_error_log __user *)args);
+		break;
+	}
+	return rc;
+}
+
 static const struct file_operations fops = {
 	.owner		= THIS_MODULE,
 	.open		= file_open,
 	.release	= file_release,
+	.unlocked_ioctl = file_ioctl,
+	.compat_ioctl   = file_ioctl,
 };
 
 /**
@@ -493,6 +674,60 @@ static int read_device_metadata(struct ocxlpmem *ocxlpmem)
 	return 0;
 }
 
+static const char *decode_error_log_type(u8 error_log_type)
+{
+	switch (error_log_type) {
+	case 0x00:
+		return "general";
+	case 0x01:
+		return "predictive failure";
+	case 0x02:
+		return "thermal warning";
+	case 0x03:
+		return "data loss";
+	case 0x04:
+		return "health & performance";
+	default:
+		return "unknown";
+	}
+}
+
+static void dump_error_log(struct ocxlpmem *ocxlpmem)
+{
+	struct ioctl_ocxlpmem_error_log log;
+	u32 buf_size;
+	u8 *buf;
+	int rc;
+
+	if (ocxlpmem->admin_command.data_size == 0)
+		return;
+
+	buf_size = ocxlpmem->admin_command.data_size - 0x48;
+	buf = kzalloc(buf_size, GFP_KERNEL);
+	if (!buf)
+		return;
+
+	log.buf_ptr = (u64)buf;
+	log.buf_size = buf_size;
+
+	rc = read_error_log(ocxlpmem, &log, false);
+	if (rc < 0)
+		goto out;
+
+	dev_warn(&ocxlpmem->dev,
+		 "OCXL PMEM Error log: WWID=0x%016llx%016llx LID=0x%x PRC=%x type=0x%x %s, Uptime=%u seconds timestamp=0x%llx\n",
+		 log.wwid[0], log.wwid[1],
+		 log.log_identifier, log.program_reference_code,
+		 log.error_log_type,
+		 decode_error_log_type(log.error_log_type),
+		 log.power_on_seconds, log.timestamp);
+	print_hex_dump(KERN_WARNING, "buf", DUMP_PREFIX_OFFSET, 16, 1, buf,
+		       log.buf_size, false);
+
+out:
+	kfree(buf);
+}
+
 /**
  * probe_function0() - Set up function 0 for an OpenCAPI persistent memory device
  * This is important as it enables templates higher than 0 across all other
@@ -656,6 +891,11 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	pci_set_drvdata(pdev, NULL);
 
 err:
+	if (ocxlpmem &&
+	    (ocxlpmem_chi(ocxlpmem, &chi) == 0) &&
+	    (chi & GLOBAL_MMIO_CHI_ELA))
+		dump_error_log(ocxlpmem);
+
 	/*
 	 * Further cleanup is done in the release handler via free_ocxlpmem()
 	 * This allows us to keep the character device live to handle IOCTLs to
diff --git a/include/uapi/nvdimm/ocxlpmem.h b/include/uapi/nvdimm/ocxlpmem.h
new file mode 100644
index 000000000000..5d3a03ea1e08
--- /dev/null
+++ b/include/uapi/nvdimm/ocxlpmem.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/* Copyright 2020 IBM Corp. */
+#ifndef _UAPI_OCXL_SCM_H
+#define _UAPI_OCXL_SCM_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+#define OCXLPMEM_ERROR_LOG_ACTION_RESET	(1 << (32 - 32))
+#define OCXLPMEM_ERROR_LOG_ACTION_CHKFW	(1 << (53 - 32))
+#define OCXLPMEM_ERROR_LOG_ACTION_REPLACE	(1 << (54 - 32))
+#define OCXLPMEM_ERROR_LOG_ACTION_DUMP		(1 << (55 - 32))
+
+#define OCXLPMEM_ERROR_LOG_TYPE_GENERAL		(0x00)
+#define OCXLPMEM_ERROR_LOG_TYPE_PREDICTIVE_FAILURE	(0x01)
+#define OCXLPMEM_ERROR_LOG_TYPE_THERMAL_WARNING	(0x02)
+#define OCXLPMEM_ERROR_LOG_TYPE_DATA_LOSS		(0x03)
+#define OCXLPMEM_ERROR_LOG_TYPE_HEALTH_PERFORMANCE	(0x04)
+
+struct ioctl_ocxlpmem_error_log {
+	__u32 log_identifier; /* out */
+	__u32 program_reference_code; /* out */
+	__u32 action_flags; /* out, recommended course of action */
+	__u32 power_on_seconds; /* out, Number of seconds the controller has been on when the error occurred */
+	__u64 timestamp; /* out, relative time since the current IPL */
+	__u64 wwid[2]; /* out, the NAA formatted WWID associated with the controller */
+	char  fw_revision[8 + 1]; /* out, firmware revision as null terminated text */
+	__u8  reserved0[7];
+	__u16 buf_size; /* in/out, buffer size provided/required.
+			 * If required is greater than provided, the buffer
+			 * will be truncated to the amount provided. If its
+			 * less, then only the required bytes will be populated.
+			 * If it is 0, then there are no more error log entries.
+			 */
+	__u8  error_log_type;
+	__u8  reserved1[5];
+	__u64 buf_ptr; /* coerced pointer to output buffer */
+	__u64 reserved2[2];
+};
+
+/* ioctl numbers */
+#define OCXLPMEM_MAGIC 0xCA
+/* OpenCAPI Persistent memory devices */
+#define IOCTL_OCXLPMEM_ERROR_LOG			_IOWR(OCXLPMEM_MAGIC, 0x30, struct ioctl_ocxlpmem_error_log)
+
+#endif /* _UAPI_OCXL_SCM_H */
-- 
2.24.1
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