Date:   Tue, 21 Sep 2021 13:43:56 -0700
From:   Russ Weight <russell.h.weight@...el.com>
To:     Xu Yilun <yilun.xu@...el.com>, Tom Rix <trix@...hat.com>
CC:     <mdf@...nel.org>, <linux-fpga@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <lgoncalv@...hat.com>,
        <hao.wu@...el.com>, <matthew.gerlach@...el.com>
Subject: Re: [PATCH v15 6/6] fpga: image-load: enable cancel of image upload



On 9/13/21 3:00 AM, Xu Yilun wrote:
> On Sat, Sep 11, 2021 at 06:13:08AM -0700, Tom Rix wrote:
>> On 9/10/21 4:38 PM, Russ Weight wrote:
>>> On 9/10/21 7:55 AM, Xu Yilun wrote:
>>>> On Wed, Sep 08, 2021 at 07:18:46PM -0700, Russ Weight wrote:
>>>>> Extend the FPGA Image Load class driver to include a cancel IOCTL that
>>>>> can be used to request that an image upload be canceled. The IOCTL may
>>>>> return EBUSY if it cannot be canceled by software or ENODEV if there
>>>>> is no update in progress.
>>>>>
>>>>> Signed-off-by: Russ Weight <russell.h.weight@...el.com>
>>>>> ---
>>>>> v15:
>>>>>   - Compare to previous patch:
>>>>>       [PATCH v14 6/6] fpga: sec-mgr: enable cancel of secure update
>>>>>   - Changed file, symbol, and config names to reflect the new driver name
>>>>>   - Cancel is now initiated by IOCT instead of sysfs
>>>>>   - Removed signed-off/reviewed-by tags
>>>>> v14:
>>>>>   - Updated ABI documentation date and kernel version
>>>>> v13:
>>>>>    - No change
>>>>> v12:
>>>>>    - Updated Date and KernelVersion fields in ABI documentation
>>>>> v11:
>>>>>    - No change
>>>>> v10:
>>>>>    - Rebased to 5.12-rc2 next
>>>>>    - Updated Date and KernelVersion in ABI documentation
>>>>> v9:
>>>>>    - Updated Date and KernelVersion in ABI documentation
>>>>> v8:
>>>>>    - No change
>>>>> v7:
>>>>>    - Changed Date in documentation file to December 2020
>>>>> v6:
>>>>>    - No change
>>>>> v5:
>>>>>    - No change
>>>>> v4:
>>>>>    - Changed from "Intel FPGA Security Manager" to FPGA Security Manager"
>>>>>      and removed unnecessary references to "Intel".
>>>>>    - Changed: iops -> sops, imgr -> smgr, IFPGA_ -> FPGA_, ifpga_ to fpga_
>>>>> v3:
>>>>>    - No change
>>>>> v2:
>>>>>    - Bumped documentation date and version
>>>>>    - Minor code cleanup per review comments
>>>>> ---
>>>>> ---
>>>>>   Documentation/fpga/fpga-image-load.rst |  6 ++++
>>>>>   drivers/fpga/fpga-image-load.c         | 45 +++++++++++++++++++++++---
>>>>>   include/linux/fpga/fpga-image-load.h   |  1 +
>>>>>   include/uapi/linux/fpga-image-load.h   |  1 +
>>>>>   4 files changed, 49 insertions(+), 4 deletions(-)
>>>>>
>>>>> diff --git a/Documentation/fpga/fpga-image-load.rst b/Documentation/fpga/fpga-image-load.rst
>>>>> index 3d5eb51223e3..763e7833a6ea 100644
>>>>> --- a/Documentation/fpga/fpga-image-load.rst
>>>>> +++ b/Documentation/fpga/fpga-image-load.rst
>>>>> @@ -37,3 +37,9 @@ FPGA_IMAGE_LOAD_STATUS:
>>>>>   Collect status for an on-going image upload. The status returned includes
>>>>>   how much data remains to be transferred, the progress of the image load,
>>>>>   and error information in the case of a failure.
>>>>> +
>>>>> +FPGA_IMAGE_LOAD_CANCEL:
>>>>> +
>>>>> +Request that a on-going image upload be cancelled. This IOCTL may return
>>>>> +EBUSY if it cannot be cancelled by software or ENODEV if there is no update
>>>>> +in progress.
>>>>> diff --git a/drivers/fpga/fpga-image-load.c b/drivers/fpga/fpga-image-load.c
>>>>> index 6ec0a39f07b3..c32e4b1ea35a 100644
>>>>> --- a/drivers/fpga/fpga-image-load.c
>>>>> +++ b/drivers/fpga/fpga-image-load.c
>>>>> @@ -46,6 +46,24 @@ static void fpga_image_dev_error(struct fpga_image_load *imgld,
>>>>>   	imgld->lops->cancel(imgld);
>>>>>   }
>>>>> +static int fpga_image_prog_transition(struct fpga_image_load *imgld,
>>>>> +				      enum fpga_image_prog new_progress)
>>>>> +{
>>>>> +	int ret = 0;
>>>>> +
>>>>> +	mutex_lock(&imgld->lock);
>>>>> +	if (imgld->request_cancel) {
>>>>> +		imgld->err_progress = imgld->progress;
>>>>> +		imgld->err_code = FPGA_IMAGE_ERR_CANCELED;
>>>>> +		imgld->lops->cancel(imgld);
>>>>> +		ret = -ECANCELED;
>>>>> +	} else {
>>>>> +		imgld->progress = new_progress;
>>>>> +	}
>>>>> +	mutex_unlock(&imgld->lock);
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>>   static void fpga_image_prog_complete(struct fpga_image_load *imgld)
>>>>>   {
>>>>>   	mutex_lock(&imgld->lock);
>>>>> @@ -77,8 +95,10 @@ static void fpga_image_do_load(struct work_struct *work)
>>>>>   		goto modput_exit;
>>>>>   	}
>>>>> -	fpga_image_update_progress(imgld, FPGA_IMAGE_PROG_WRITING);
>>>>> -	while (imgld->remaining_size) {
>>>>> +	if (fpga_image_prog_transition(imgld, FPGA_IMAGE_PROG_WRITING))
>>>>> +		goto done;
>>>>> +
>>>>> +	while (imgld->remaining_size && !imgld->request_cancel) {
>>>>>   		ret = imgld->lops->write_blk(imgld, offset);
>>>>>   		if (ret != FPGA_IMAGE_ERR_NONE) {
>>>>>   			fpga_image_dev_error(imgld, ret);
>>>>> @@ -88,7 +108,9 @@ static void fpga_image_do_load(struct work_struct *work)
>>>>>   		offset = size - imgld->remaining_size;
>>>>>   	}
>>>>> -	fpga_image_update_progress(imgld, FPGA_IMAGE_PROG_PROGRAMMING);
>>>>> +	if (fpga_image_prog_transition(imgld, FPGA_IMAGE_PROG_PROGRAMMING))
>>>>> +		goto done;
>>>>> +
>>>>>   	ret = imgld->lops->poll_complete(imgld);
>>>>>   	if (ret != FPGA_IMAGE_ERR_NONE)
>>>>>   		fpga_image_dev_error(imgld, ret);
>>>>> @@ -159,6 +181,7 @@ static int fpga_image_load_ioctl_write(struct fpga_image_load *imgld,
>>>>>   	imgld->remaining_size = wb.size;
>>>>>   	imgld->err_code = FPGA_IMAGE_ERR_NONE;
>>>>>   	imgld->progress = FPGA_IMAGE_PROG_STARTING;
>>>>> +	imgld->request_cancel = false;
>>>>>   	reinit_completion(&imgld->update_done);
>>>>>   	schedule_work(&imgld->work);
>>>>>   	return 0;
>>>>> @@ -189,7 +212,7 @@ static long fpga_image_load_ioctl(struct file *filp, unsigned int cmd,
>>>>>   				  unsigned long arg)
>>>>>   {
>>>>>   	struct fpga_image_load *imgld = filp->private_data;
>>>>> -	int ret = -ENOTTY;
>>>>> +	int ret = 0;
>>>>>   	mutex_lock(&imgld->lock);
>>>>> @@ -200,6 +223,17 @@ static long fpga_image_load_ioctl(struct file *filp, unsigned int cmd,
>>>>>   	case FPGA_IMAGE_LOAD_STATUS:
>>>>>   		ret = fpga_image_load_ioctl_status(imgld, arg);
>>>>>   		break;
>>>>> +	case FPGA_IMAGE_LOAD_CANCEL:
>>>>> +		if (imgld->progress == FPGA_IMAGE_PROG_PROGRAMMING)
>>>>> +			ret = -EBUSY;
>>>>> +		else if (imgld->progress == FPGA_IMAGE_PROG_IDLE)
>>>>> +			ret = -ENODEV;
>>>>> +		else
>>>>> +			imgld->request_cancel = true;
>>>>> +		break;
>>>>> +	default:
>>>>> +		ret = -ENOTTY;
>>>>> +		break;
>>>>>   	}
>>>>>   	mutex_unlock(&imgld->lock);
>>>>> @@ -374,6 +408,9 @@ void fpga_image_load_unregister(struct fpga_image_load *imgld)
>>>>>   		goto unregister;
>>>>>   	}
>>>>> +	if (imgld->progress != FPGA_IMAGE_PROG_PROGRAMMING)
>>>>> +		imgld->request_cancel = true;
>>>>> +
>>>> Why we cancel the programing rather than waiting for programing done?
>>> This isn't new - it is the way the security manager was implemented.
>>>
>>> Updates can take up to 40 minutes for the N3000. If a person tries
>>> to unload the driver modules, should we hang for 40 minutes? Or should
>>> we try to cancel the update and allow the module to be unloaded?
>>> I think it is reasonable to cancel the update (if possible) under these
>>> circumstances. What do you think?
>> I do not think stalling a shutdown for 40 minutes is good.
>>
>> Is there a chance that cancelling would brick the card?
> If the cancel cannot be possible, may be we could wait. Or the user
> image would be corrupted with a simple poweroff command.

OK - I'm leaving the above code in for cancelling. The check for
FPGA_IMAGE_PROG_PROGRAMMING ensures that it can be safely canceled.
Once programming begins, then we will block until it is complete.
I'm still using the driver-unload flag to prevent new uploads from
starting, but driver_unload will no longer be used to force an exit
from the lower-level driver.

The maximum wait for programming is less than 40 minutes - probably
more like 20 minutes?

- Russ

>
> Thanks,
> Yilun
>
>> After restarting, can the hw detect an interrupted update ?
>>
>> Tom
>>
>>> - Russ
>>>
>>>> Thanks,
>>>> Yilun
>>>>
>>>>>   	mutex_unlock(&imgld->lock);
>>>>>   	wait_for_completion(&imgld->update_done);
>>>>> diff --git a/include/linux/fpga/fpga-image-load.h b/include/linux/fpga/fpga-image-load.h
>>>>> index 68f3105b51d2..4e51b9fd1724 100644
>>>>> --- a/include/linux/fpga/fpga-image-load.h
>>>>> +++ b/include/linux/fpga/fpga-image-load.h
>>>>> @@ -52,6 +52,7 @@ struct fpga_image_load {
>>>>>   	enum fpga_image_prog progress;
>>>>>   	enum fpga_image_prog err_progress;	/* progress at time of failure */
>>>>>   	enum fpga_image_err err_code;		/* image load error code */
>>>>> +	bool request_cancel;
>>>>>   	bool driver_unload;
>>>>>   	struct eventfd_ctx *finished;
>>>>>   	void *priv;
>>>>> diff --git a/include/uapi/linux/fpga-image-load.h b/include/uapi/linux/fpga-image-load.h
>>>>> index 6a995bcc0fb7..8d0dfa1f9b77 100644
>>>>> --- a/include/uapi/linux/fpga-image-load.h
>>>>> +++ b/include/uapi/linux/fpga-image-load.h
>>>>> @@ -39,6 +39,7 @@ enum fpga_image_err {
>>>>>   #define FPGA_IMAGE_LOAD_WRITE	_IOW(FPGA_IMAGE_LOAD_MAGIC, 0, struct fpga_image_write)
>>>>>   #define FPGA_IMAGE_LOAD_STATUS	_IOR(FPGA_IMAGE_LOAD_MAGIC, 1, struct fpga_image_status)
>>>>> +#define FPGA_IMAGE_LOAD_CANCEL	_IO(FPGA_IMAGE_LOAD_MAGIC, 2)
>>>>>   /**
>>>>>    * FPGA_IMAGE_LOAD_WRITE - _IOW(FPGA_IMAGE_LOAD_MAGIC, 0,
>>>>> -- 
>>>>> 2.25.1

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