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 <alast...@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.kl...@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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