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Subject: Re: [PATCH v3 17/27] powerpc/powernv/pmem: Implement the Read Error
 Log command
To:     "Alastair D'Silva" <alastair@au1.ibm.com>, alastair@d-silva.org
Cc:     "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        "Oliver O'Halloran" <oohall@gmail.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Frederic Barrat <fbarrat@linux.ibm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Rob Herring <robh@kernel.org>,
        Anton Blanchard <anton@ozlabs.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
        =?UTF-8?Q?C=c3=a9dric_Le_Goater?= <clg@kaod.org>,
        Anju T Sudhakar <anju@linux.vnet.ibm.com>,
        Hari Bathini <hbathini@linux.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kurz <groug@kaod.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Alexey Kardashevskiy <aik@ozlabs.ru>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-nvdimm@lists.01.org, linux-mm@kvack.org
References: <20200221032720.33893-1-alastair@au1.ibm.com>
 <20200221032720.33893-18-alastair@au1.ibm.com>
From:   Andrew Donnellan <ajd@linux.ibm.com>
Date:   Wed, 4 Mar 2020 16:58:25 +1100
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On 21/2/20 2:27 pm, Alastair D'Silva wrote:
> From: 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>

A few minor style checks at 
https://openpower.xyz/job/snowpatch/job/snowpatch-linux-checkpatch/11787//artifact/linux/checkpatch.log

We should also add some documentation for the user interfaces we're 
adding (same applies for all the remaining patches in this series that 
add more interfaces).

> ---
>   arch/powerpc/platforms/powernv/pmem/ocxl.c    | 269 ++++++++++++++++++
>   .../platforms/powernv/pmem/ocxl_internal.h    |   1 +
>   include/uapi/nvdimm/ocxl-pmem.h               |  46 +++
>   3 files changed, 316 insertions(+)
>   create mode 100644 include/uapi/nvdimm/ocxl-pmem.h
> 
> diff --git a/arch/powerpc/platforms/powernv/pmem/ocxl.c b/arch/powerpc/platforms/powernv/pmem/ocxl.c
> index 63109a870d2c..2b64504f9129 100644
> --- a/arch/powerpc/platforms/powernv/pmem/ocxl.c
> +++ b/arch/powerpc/platforms/powernv/pmem/ocxl.c
> @@ -447,10 +447,219 @@ 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;

This should be something other than EINVAL I think

> +	}
> +
> +	*length = data_length;
> +	return 0;
> +}
> +
> +static int error_log_offset_0x08(struct ocxlpmem *ocxlpmem,
> +				 u32 *log_identifier, u32 *program_ref_code)
> +{
> +	int rc;
> +	u64 val;
> +
> +	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
> +				     ocxlpmem->admin_command.data_offset + 0x08,
> +				     OCXL_LITTLE_ENDIAN, &val);
> +	if (rc)
> +		return rc;
> +
> +	*log_identifier = val >> 32;
> +	*program_ref_code = val & 0xFFFFFFFF;
> +
> +	return 0;
> +}
> +
> +static int read_error_log(struct ocxlpmem *ocxlpmem,
> +			  struct ioctl_ocxl_pmem_error_log *log, bool buf_is_user)
> +{
> +	u64 val;
> +	u16 user_buf_length;
> +	u16 buf_length;
> +	u16 i;
> +	int rc;
> +
> +	if (log->buf_size % 8)
> +		return -EINVAL;
> +
> +	rc = ocxlpmem_chi(ocxlpmem, &val);
> +	if (rc)
> +		goto out;
> +
> +	if (!(val & GLOBAL_MMIO_CHI_ELA))
> +		return -EAGAIN;
> +
> +	user_buf_length = log->buf_size;
> +
> +	mutex_lock(&ocxlpmem->admin_command.lock);
> +
> +	rc = admin_command_request(ocxlpmem, ADMIN_COMMAND_ERRLOG);
> +	if (rc)
> +		goto out;
> +
> +	rc = admin_command_execute(ocxlpmem);
> +	if (rc)
> +		goto out;
> +
> +	rc = admin_command_complete_timeout(ocxlpmem, ADMIN_COMMAND_ERRLOG);
> +	if (rc < 0) {
> +		dev_warn(&ocxlpmem->dev, "Read error log timed out\n");
> +		goto out;
> +	}
> +
> +	rc = admin_response(ocxlpmem);
> +	if (rc < 0)
> +		goto out;
> +	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

In the event that the log is truncated to fit the user buffer, we return 
the full log size, I assume this is intentional to signal it's truncated 
as per the nd stuff?

> +
> +	rc = error_log_offset_0x08(ocxlpmem, &log->log_identifier,
> +				       &log->program_reference_code);
> +	if (rc)
> +		goto out;
> +
> +	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 == OCXL_PMEM_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_HOST_ENDIAN, &log->wwid[0]);
> +	if (rc)
> +		goto out;
> +
> +	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
> +				     ocxlpmem->admin_command.data_offset + 0x28,
> +				     OCXL_HOST_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);

Why the difference between HOST and LITTLE_ENDIAN between these fields?

> +	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 + 0x48; i += 8) {

+ 0x48 here doesn't look right...

> +		u64 val;
> +
> +		rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
> +					     ocxlpmem->admin_command.data_offset + i,

...did you mean to add 0x48 here?

> +					     OCXL_HOST_ENDIAN, &val);
> +		if (rc)
> +			goto out;
> +
> +		if (buf_is_user) {
> +			if (copy_to_user(&log->buf[i], &val, sizeof(u64))) {
> +				rc = -EFAULT;
> +				goto out;
> +			}
> +		} else
> +			log->buf[i] = val;

Please use braces consistently on both sides of if/else.

> +	}
> +
> +	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_ocxl_pmem_error_log __user *uarg)
> +{
> +	struct ioctl_ocxl_pmem_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_OCXL_PMEM_ERROR_LOG:
> +		rc = ioctl_error_log(ocxlpmem,
> +				     (struct ioctl_ocxl_pmem_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,
>   };
>   
>   /**
> @@ -527,6 +736,60 @@ 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_ocxl_pmem_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 = 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 functions,
> @@ -568,6 +831,7 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>   	struct ocxlpmem *ocxlpmem;
>   	int rc;
>   	u16 elapsed, timeout;
> +	u64 chi;
>   
>   	if (PCI_FUNC(pdev->devfn) == 0)
>   		return probe_function0(pdev);
> @@ -667,6 +931,11 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>   	return 0;
>   
>   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/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h b/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> index d2d81fec7bb1..b953ee522ed4 100644
> --- a/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> +++ b/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> @@ -5,6 +5,7 @@
>   #include <linux/cdev.h>
>   #include <misc/ocxl.h>
>   #include <linux/libnvdimm.h>
> +#include <uapi/nvdimm/ocxl-pmem.h>
>   #include <linux/mm.h>
>   
>   #define LABEL_AREA_SIZE	(1UL << PA_SECTION_SHIFT)
> diff --git a/include/uapi/nvdimm/ocxl-pmem.h b/include/uapi/nvdimm/ocxl-pmem.h
> new file mode 100644
> index 000000000000..b10f8ac0c20f
> --- /dev/null
> +++ b/include/uapi/nvdimm/ocxl-pmem.h
> @@ -0,0 +1,46 @@
> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
> +/* Copyright 2017 IBM Corp. */
> +#ifndef _UAPI_OCXL_SCM_H
> +#define _UAPI_OCXL_SCM_H
> +
> +#include <linux/types.h>
> +#include <linux/ioctl.h>
> +
> +#define OCXL_PMEM_ERROR_LOG_ACTION_RESET	(1 << (32-32))
> +#define OCXL_PMEM_ERROR_LOG_ACTION_CHKFW	(1 << (53-32))
> +#define OCXL_PMEM_ERROR_LOG_ACTION_REPLACE	(1 << (54-32))
> +#define OCXL_PMEM_ERROR_LOG_ACTION_DUMP		(1 << (55-32))
> +
> +#define OCXL_PMEM_ERROR_LOG_TYPE_GENERAL		(0x00)
> +#define OCXL_PMEM_ERROR_LOG_TYPE_PREDICTIVE_FAILURE	(0x01)
> +#define OCXL_PMEM_ERROR_LOG_TYPE_THERMAL_WARNING	(0x02)
> +#define OCXL_PMEM_ERROR_LOG_TYPE_DATA_LOSS		(0x03)
> +#define OCXL_PMEM_ERROR_LOG_TYPE_HEALTH_PERFORMANCE	(0x04)
> +
> +struct ioctl_ocxl_pmem_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 */
> +	__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;
> +	__u32 reserved2;
> +	__u64 reserved3[2];
> +	__u8 *buf; /* pointer to output buffer */
> +};
> +
> +/* ioctl numbers */
> +#define OCXL_PMEM_MAGIC 0x5C
> +/* SCM devices */
> +#define IOCTL_OCXL_PMEM_ERROR_LOG			_IOWR(OCXL_PMEM_MAGIC, 0x01, struct ioctl_ocxl_pmem_error_log)
> +
> +#endif /* _UAPI_OCXL_SCM_H */
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
ajd@linux.ibm.com             IBM Australia Limited