RE: [PATCH v2 4/7] fpga: sec-mgr: expose sec-mgr update errors

["Wu, Hao" <hao.wu@intel.com>]

> Subject: [PATCH v2 4/7] fpga: sec-mgr: expose sec-mgr update errors
> 
> Extend Intel Security Manager class driver to include
> an update/error sysfs node that can be read for error
> information when a secure update fails.
> 
> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> ---
> v2:
>   - Bumped documentation date and version
>   - Added warning to sec_progress() for invalid progress status
>   - Added sec_error() function (similar to sec_progress())
> ---
>  .../ABI/testing/sysfs-class-ifpga-sec-mgr     | 17 ++++
>  drivers/fpga/ifpga-sec-mgr.c                  | 81 ++++++++++++++++---
>  include/linux/fpga/ifpga-sec-mgr.h            |  1 +
>  3 files changed, 89 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> b/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> index 73a5246fea1b..1f9f2c215e0c 100644
> --- a/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> +++ b/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> @@ -89,3 +89,20 @@ Description:	Read-only. Returns a string describing
> the current
>  		programming. Userspace code can poll on this file,
>  		as it will be signaled by sysfs_notify() on each
>  		state change.
> +
> +What: 		/sys/class/ifpga_sec_mgr/ifpga_secX/update/error
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@intel.com>
> +Description:	Read-only. Returns a string describing the failure
> +		of a secure update. This string will be in the form
> +		of <STATUS>:<ERROR>, where <STATUS> will be one of
> +		the status strings described for the status sysfs
> +		file and <ERROR> will be one of the following:
> +		hw-error, timeout, user-abort, device-busy,
> +		invalid-file-size, read-write-error, flash-wearout,
> +		file-read-error.  The error sysfs file is only
> +		meaningful when the secure update engine is in the
> +		idle state. If this file is read while a secure
> +		update is in progress, then the read will fail with
> +		EBUSY.
> diff --git a/drivers/fpga/ifpga-sec-mgr.c b/drivers/fpga/ifpga-sec-mgr.c
> index ad918fb42dc2..456ea0b71e3d 100644
> --- a/drivers/fpga/ifpga-sec-mgr.c
> +++ b/drivers/fpga/ifpga-sec-mgr.c
> @@ -146,10 +146,16 @@ static void update_progress(struct ifpga_sec_mgr
> *imgr,
>  	sysfs_notify(&imgr->dev.kobj, "update", "status");
>  }
> 
> +static void set_error(struct ifpga_sec_mgr *imgr, enum ifpga_sec_err
> err_code)
> +{
> +	imgr->err_state = imgr->progress;
> +	imgr->err_code = err_code;
> +}
> +
>  static void ifpga_sec_dev_error(struct ifpga_sec_mgr *imgr,
>  				enum ifpga_sec_err err_code)
>  {
> -	imgr->err_code = err_code;
> +	set_error(imgr, err_code);
>  	imgr->iops->cancel(imgr);
>  }
> 
> @@ -172,7 +178,7 @@ static void ifpga_sec_mgr_update(struct work_struct
> *work)
> 
>  	get_device(&imgr->dev);
>  	if (request_firmware(&fw, imgr->filename, &imgr->dev)) {
> -		imgr->err_code = IFPGA_SEC_ERR_FILE_READ;
> +		set_error(imgr, IFPGA_SEC_ERR_FILE_READ);
>  		goto idle_exit;
>  	}
> 
> @@ -180,7 +186,7 @@ static void ifpga_sec_mgr_update(struct work_struct
> *work)
>  	imgr->remaining_size = fw->size;
> 
>  	if (!try_module_get(imgr->dev.parent->driver->owner)) {
> -		imgr->err_code = IFPGA_SEC_ERR_BUSY;
> +		set_error(imgr, IFPGA_SEC_ERR_BUSY);
>  		goto release_fw_exit;
>  	}
> 
> @@ -274,22 +280,76 @@ static const char * const sec_mgr_prog_str[] = {
>  	"programming"		/* IFPGA_SEC_PROG_PROGRAMMING */
>  };
> 
> -static ssize_t
> -status_show(struct device *dev, struct device_attribute *attr, char *buf)
> +static const char * const sec_mgr_err_str[] = {
> +	"none",			/* IFPGA_SEC_ERR_NONE */
> +	"hw-error",		/* IFPGA_SEC_ERR_HW_ERROR */
> +	"timeout",		/* IFPGA_SEC_ERR_TIMEOUT */
> +	"user-abort",		/* IFPGA_SEC_ERR_CANCELED */
> +	"device-busy",		/* IFPGA_SEC_ERR_BUSY */
> +	"invalid-file-size",	/* IFPGA_SEC_ERR_INVALID_SIZE */
> +	"read-write-error",	/* IFPGA_SEC_ERR_RW_ERROR */
> +	"flash-wearout",	/* IFPGA_SEC_ERR_WEAROUT */
> +	"file-read-error"	/* IFPGA_SEC_ERR_FILE_READ */
> +};
> +
> +static const char *sec_progress(struct device *dev, enum ifpga_sec_prog
> prog)
>  {
> -	struct ifpga_sec_mgr *imgr = to_sec_mgr(dev);
>  	const char *status = "unknown-status";
> 
> -	if (imgr->progress < IFPGA_SEC_PROG_MAX)
> -		status = sec_mgr_prog_str[imgr->progress];
> +	if (prog < IFPGA_SEC_PROG_MAX)
> +		status = sec_mgr_prog_str[prog];
>  	else
>  		dev_warn(dev, "Invalid status during secure update: %d\n",
> -			 imgr->progress);
> +			 prog);
> +
> +	return status;
> +}
> +
> +static const char *sec_error(struct device *dev, enum ifpga_sec_err
> err_code)
> +{
> +	const char *error = "unknown-error";
> +
> +	if (err_code < IFPGA_SEC_ERR_MAX)
> +		error = sec_mgr_err_str[err_code];
> +	else
> +		dev_warn(dev, "Invalid error code during secure
> update: %d\n",
> +			 err_code);
> +
> +	return error;
> +}
> +
> +static ssize_t
> +status_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct ifpga_sec_mgr *imgr = to_sec_mgr(dev);
> 
> -	return sprintf(buf, "%s\n", status);
> +	return sprintf(buf, "%s\n", sec_progress(dev, imgr->progress));
>  }
>  static DEVICE_ATTR_RO(status);
> 
> +static ssize_t
> +error_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct ifpga_sec_mgr *imgr = to_sec_mgr(dev);
> +	int ret;
> +
> +	mutex_lock(&imgr->lock);
> +
> +	if (imgr->progress != IFPGA_SEC_PROG_IDLE)
> +		ret = -EBUSY;
> +	else if (!imgr->err_code)
> +		ret = 0;
> +	else
> +		ret = sprintf(buf, "%s:%s\n",
> +			      sec_progress(dev, imgr->err_state),
> +			      sec_error(dev, imgr->err_code));

In scheduled work for update, there is no lock protection, would that be a 
real problem here? e.g. progress is changed, or err_state and err_code
are not matched.

Thanks
Hao

> +
> +	mutex_unlock(&imgr->lock);
> +
> +	return ret;
> +}
> +static DEVICE_ATTR_RO(error);
> +
>  static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
>  			      const char *buf, size_t count)
>  {
> @@ -325,6 +385,7 @@ static DEVICE_ATTR_WO(filename);
>  static struct attribute *sec_mgr_update_attrs[] = {
>  	&dev_attr_filename.attr,
>  	&dev_attr_status.attr,
> +	&dev_attr_error.attr,
>  	NULL,
>  };
> 
> diff --git a/include/linux/fpga/ifpga-sec-mgr.h b/include/linux/fpga/ifpga-
> sec-mgr.h
> index 27008abd8e75..246e3d452c59 100644
> --- a/include/linux/fpga/ifpga-sec-mgr.h
> +++ b/include/linux/fpga/ifpga-sec-mgr.h
> @@ -110,6 +110,7 @@ struct ifpga_sec_mgr {
>  	const u8 *data;			/* pointer to update data */
>  	u32 remaining_size;		/* size remaining to transfer */
>  	enum ifpga_sec_prog progress;
> +	enum ifpga_sec_prog err_state;	/* progress state at time of
> failure */
>  	enum ifpga_sec_err err_code;	/* security manager error code */
>  	bool driver_unload;
>  	void *priv;
> --
> 2.17.1