On Sun, May 16, 2021 at 07:31:55PM -0700, Moritz Fischer wrote:
> From: Russ Weight <russell.h.weight@xxxxxxxxx>
>
> Extend the FPGA Security Manager class driver to include
> an optional update/hw_errinfo sysfs node that can be used
> to retrieve 64 bits of device specific error information
> following a secure update failure.
>
> The underlying driver must provide a get_hw_errinfo() callback
> function to enable this feature. This data is treated as
> opaque by the class driver. It is left to user-space software
> or support personnel to interpret this data.
No, you don't provide "opaque" data to userspace, that's a sure way to
make it such that no one knows what this data is supposed to be, and so
it can not be maintained at all.
>
> Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
> Reviewed-by: Tom Rix <trix@xxxxxxxxxx>
> Signed-off-by: Moritz Fischer <mdf@xxxxxxxxxx>
> ---
> .../ABI/testing/sysfs-class-fpga-sec-mgr | 14 +++++++
> drivers/fpga/fpga-sec-mgr.c | 38 +++++++++++++++++++
> include/linux/fpga/fpga-sec-mgr.h | 5 +++
> 3 files changed, 57 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> index 749f2d4c78d3..f1881ce39c63 100644
> --- a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> +++ b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> @@ -65,3 +65,17 @@ Description: Read-only. Returns a string describing the failure
> idle state. If this file is read while a secure
> update is in progress, then the read will fail with
> EBUSY.
> +
> +What: /sys/class/fpga_sec_mgr/fpga_secX/update/hw_errinfo
> +Date: June 2021
> +KernelVersion: 5.14
> +Contact: Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description: Read-only. Returns a 64 bit error value providing
> + hardware specific information that may be useful in
> + debugging errors that occur during FPGA image updates.
> + This file is only visible if the underlying device
> + supports it. The hw_errinfo value is only accessible
> + 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.
> + Format: "0x%llx".
> diff --git a/drivers/fpga/fpga-sec-mgr.c b/drivers/fpga/fpga-sec-mgr.c
> index 48950843c2b4..cefe9182c3c3 100644
> --- a/drivers/fpga/fpga-sec-mgr.c
> +++ b/drivers/fpga/fpga-sec-mgr.c
> @@ -36,10 +36,17 @@ static void fpga_sec_set_error(struct fpga_sec_mgr *smgr, enum fpga_sec_err err_
> smgr->err_code = err_code;
> }
>
> +static void fpga_sec_set_hw_errinfo(struct fpga_sec_mgr *smgr)
> +{
> + if (smgr->sops->get_hw_errinfo)
> + smgr->hw_errinfo = smgr->sops->get_hw_errinfo(smgr);
> +}
> +
> static void fpga_sec_dev_error(struct fpga_sec_mgr *smgr,
> enum fpga_sec_err err_code)
> {
> fpga_sec_set_error(smgr, err_code);
> + fpga_sec_set_hw_errinfo(smgr);
> smgr->sops->cancel(smgr);
> }
>
> @@ -221,6 +228,23 @@ error_show(struct device *dev, struct device_attribute *attr, char *buf)
> }
> static DEVICE_ATTR_RO(error);
>
> +static ssize_t
> +hw_errinfo_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct fpga_sec_mgr *smgr = to_sec_mgr(dev);
> + int ret;
> +
> + mutex_lock(&smgr->lock);
> + if (smgr->progress != FPGA_SEC_PROG_IDLE)
> + ret = -EBUSY;
Why does the state matter here?
greg k-h
