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Date: Mon, 10 May 2021 10:40:18 -0700
From: Moritz Fischer <mdf@...nel.org>
To: Russ Weight <russell.h.weight@...el.com>
Cc: mdf@...nel.org, linux-fpga@...r.kernel.org,
linux-kernel@...r.kernel.org, trix@...hat.com, lgoncalv@...hat.com,
yilun.xu@...el.com, hao.wu@...el.com, matthew.gerlach@...el.com,
richard.gong@...el.com
Subject: Re: [PATCH v12 6/7] fpga: sec-mgr: enable cancel of secure update
On Mon, May 03, 2021 at 02:35:45PM -0700, Russ Weight wrote:
> Extend the FPGA Security Manager class driver to include
> an update/cancel sysfs file that can be written to request
> that an update be canceled. The write may return EBUSY if
> the update has progressed to the point that 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>
> Reviewed-by: Tom Rix <trix@...hat.com>
> ---
> 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
> ---
> .../ABI/testing/sysfs-class-fpga-sec-mgr | 10 ++++
> drivers/fpga/fpga-sec-mgr.c | 59 +++++++++++++++++--
> include/linux/fpga/fpga-sec-mgr.h | 1 +
> 3 files changed, 66 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> index c5d0b9d7c7e4..749f2d4c78d3 100644
> --- a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> +++ b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> @@ -17,6 +17,16 @@ Description: Write only. Write the filename of an image
> and Root Entry Hashes, and to cancel Code Signing
> Keys (CSK).
>
> +What: /sys/class/fpga_sec_mgr/fpga_secX/update/cancel
> +Date: June 2021
> +KernelVersion: 5.14
> +Contact: Russ Weight <russell.h.weight@...el.com>
> +Description: Write-only. Write a "1" to this file to request
> + that a current update be canceled. This request
> + will be rejected (EBUSY) if the programming phase
> + has already started or (ENODEV) if there is no
> + update in progress.
> +
> What: /sys/class/fpga_sec_mgr/fpga_secX/update/status
> Date: June 2021
> KernelVersion: 5.14
> diff --git a/drivers/fpga/fpga-sec-mgr.c b/drivers/fpga/fpga-sec-mgr.c
> index 2487042ace82..35bd419bd3b9 100644
> --- a/drivers/fpga/fpga-sec-mgr.c
> +++ b/drivers/fpga/fpga-sec-mgr.c
> @@ -43,6 +43,23 @@ static void fpga_sec_dev_error(struct fpga_sec_mgr *smgr,
> smgr->sops->cancel(smgr);
> }
>
> +static int progress_transition(struct fpga_sec_mgr *smgr,
> + enum fpga_sec_prog new_progress)
> +{
> + int ret = 0;
> +
> + mutex_lock(&smgr->lock);
> + if (smgr->request_cancel) {
> + set_error(smgr, FPGA_SEC_ERR_CANCELED);
> + smgr->sops->cancel(smgr);
> + ret = -ECANCELED;
> + } else {
> + update_progress(smgr, new_progress);
> + }
> + mutex_unlock(&smgr->lock);
> + return ret;
> +}
> +
> static void progress_complete(struct fpga_sec_mgr *smgr)
> {
> mutex_lock(&smgr->lock);
> @@ -74,15 +91,19 @@ static void fpga_sec_mgr_update(struct work_struct *work)
> goto release_fw_exit;
> }
>
> - update_progress(smgr, FPGA_SEC_PROG_PREPARING);
> + if (progress_transition(smgr, FPGA_SEC_PROG_PREPARING))
> + goto modput_exit;
> +
> ret = smgr->sops->prepare(smgr);
> if (ret != FPGA_SEC_ERR_NONE) {
> fpga_sec_dev_error(smgr, ret);
> goto modput_exit;
> }
>
> - update_progress(smgr, FPGA_SEC_PROG_WRITING);
> - while (smgr->remaining_size) {
> + if (progress_transition(smgr, FPGA_SEC_PROG_WRITING))
> + goto done;
> +
> + while (smgr->remaining_size && !smgr->request_cancel) {
> ret = smgr->sops->write_blk(smgr, offset);
> if (ret != FPGA_SEC_ERR_NONE) {
> fpga_sec_dev_error(smgr, ret);
> @@ -92,7 +113,9 @@ static void fpga_sec_mgr_update(struct work_struct *work)
> offset = fw->size - smgr->remaining_size;
> }
>
> - update_progress(smgr, FPGA_SEC_PROG_PROGRAMMING);
> + if (progress_transition(smgr, FPGA_SEC_PROG_PROGRAMMING))
> + goto done;
> +
> ret = smgr->sops->poll_complete(smgr);
> if (ret != FPGA_SEC_ERR_NONE)
> fpga_sec_dev_error(smgr, ret);
> @@ -229,6 +252,7 @@ static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
> }
>
> smgr->err_code = FPGA_SEC_ERR_NONE;
> + smgr->request_cancel = false;
> smgr->progress = FPGA_SEC_PROG_READING;
> reinit_completion(&smgr->update_done);
> schedule_work(&smgr->work);
> @@ -239,8 +263,32 @@ static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
> }
> static DEVICE_ATTR_WO(filename);
>
> +static ssize_t cancel_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct fpga_sec_mgr *smgr = to_sec_mgr(dev);
> + bool cancel;
> + int ret = count;
> +
> + if (kstrtobool(buf, &cancel) || !cancel)
> + return -EINVAL;
> +
> + mutex_lock(&smgr->lock);
> + if (smgr->progress == FPGA_SEC_PROG_PROGRAMMING)
> + ret = -EBUSY;
> + else if (smgr->progress == FPGA_SEC_PROG_IDLE)
> + ret = -ENODEV;
> + else
> + smgr->request_cancel = true;
> + mutex_unlock(&smgr->lock);
> +
> + return ret;
> +}
> +static DEVICE_ATTR_WO(cancel);
> +
> static struct attribute *sec_mgr_update_attrs[] = {
> &dev_attr_filename.attr,
> + &dev_attr_cancel.attr,
> &dev_attr_status.attr,
> &dev_attr_error.attr,
> &dev_attr_remaining_size.attr,
> @@ -464,6 +512,9 @@ void fpga_sec_mgr_unregister(struct fpga_sec_mgr *smgr)
> goto unregister;
> }
>
> + if (smgr->progress != FPGA_SEC_PROG_PROGRAMMING)
> + smgr->request_cancel = true;
> +
> mutex_unlock(&smgr->lock);
> wait_for_completion(&smgr->update_done);
>
> diff --git a/include/linux/fpga/fpga-sec-mgr.h b/include/linux/fpga/fpga-sec-mgr.h
> index 6b7b8a3d6aac..0e1f50434024 100644
> --- a/include/linux/fpga/fpga-sec-mgr.h
> +++ b/include/linux/fpga/fpga-sec-mgr.h
> @@ -72,6 +72,7 @@ struct fpga_sec_mgr {
> enum fpga_sec_prog progress;
> enum fpga_sec_prog err_state; /* progress state at time of failure */
> enum fpga_sec_err err_code; /* security manager error code */
> + bool request_cancel;
> bool driver_unload;
> void *priv;
> };
> --
> 2.25.1
>
Looks good,
Moritz
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