[PATCH v5 7/7] fpga: sec-mgr: expose hardware error info

Russ Weight
2020-10-21T00:17:14Z

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.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Tom Rix <trix@redhat.com>
---
v5:

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
---
.../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 814271aede05..5a2dad0d0941 100644
--- a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
+++ b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
@@ -127,3 +127,17 @@ 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: Oct 2020
+KernelVersion: 5.11
+Contact: Russ Weight <russell.h.weight@intel.com>
+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 9ec7092e9ede..7ea60147b248 100644
--- a/drivers/fpga/fpga-sec-mgr.c
+++ b/drivers/fpga/fpga-sec-mgr.c
@@ -156,10 +156,17 @@ static void set_error(struct fpga_sec_mgr *smgr, enum fpga_sec_err err_code)
smgr->err_code = err_code;
}

+static void 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)
{
set_error(smgr, err_code);
+ set_hw_errinfo(smgr);
smgr->sops->cancel(smgr);
}

@@ -375,6 +382,23 @@ 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;
+ else
+ ret = sysfs_emit(buf, "0x%llx\n", smgr->hw_errinfo);
+ mutex_unlock(&smgr->lock);
+
+ return ret;
+}
+static DEVICE_ATTR_RO(hw_errinfo);
+
static ssize_t remaining_size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -406,6 +430,7 @@ static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
}

smgr->err_code = FPGA_SEC_ERR_NONE;
+ smgr->hw_errinfo = 0;
smgr->request_cancel = false;
smgr->progress = FPGA_SEC_PROG_READING;
reinit_completion(&smgr->update_done);
@@ -440,18 +465,31 @@ static ssize_t cancel_store(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_WO(cancel);

+static umode_t
+sec_mgr_update_visible(struct kobject *kobj, struct attribute *attr, int n)
+{
+ struct fpga_sec_mgr *smgr = to_sec_mgr(kobj_to_dev(kobj));
+
+ if (attr == &dev_attr_hw_errinfo.attr && !smgr->sops->get_hw_errinfo)
+ return 0;
+
+ return attr->mode;
+}
+
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,
+ &dev_attr_hw_errinfo.attr,
NULL,
};

static struct attribute_group sec_mgr_update_attr_group = {
.name = "update",
.attrs = sec_mgr_update_attrs,
+ .is_visible = sec_mgr_update_visible,
};

static ssize_t name_show(struct device *dev,
diff --git a/include/linux/fpga/fpga-sec-mgr.h b/include/linux/fpga/fpga-sec-mgr.h
index c6906c6d1d41..697cf28b6a99 100644
--- a/include/linux/fpga/fpga-sec-mgr.h
+++ b/include/linux/fpga/fpga-sec-mgr.h
@@ -60,6 +60,9 @@ enum fpga_sec_err {
* function and is called at the completion
* of the update, whether success or failure,
* if the prepare function succeeded.
+ * @get_hw_errinfo: Optional: Return u64 hw specific error info.
+ * The software err_code may used to determine
+ * whether the hw error info is applicable.
*/
struct fpga_sec_mgr_ops {
int (*user_flash_count)(struct fpga_sec_mgr *smgr);
@@ -87,6 +90,7 @@ struct fpga_sec_mgr_ops {
enum fpga_sec_err (*poll_complete)(struct fpga_sec_mgr *smgr);
void (*cleanup)(struct fpga_sec_mgr *smgr);
enum fpga_sec_err (*cancel)(struct fpga_sec_mgr *smgr);
+ u64 (*get_hw_errinfo)(struct fpga_sec_mgr *smgr);
};

/* Update progress codes */
@@ -112,6 +116,7 @@ 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 */
+ u64 hw_errinfo; /* 64 bits of HW specific error info */
bool request_cancel;
bool driver_unload;
void *priv;
--
2.25.1