Re: [PATCH v14 1/4] fpga: m10bmc-sec: create max10 bmc secure update driver

From: Tom Rix
Date: Mon Sep 13 2021 - 08:12:43 EST



On 9/12/21 10:37 PM, Xu Yilun wrote:
On Sat, Sep 11, 2021 at 12:04:07PM -0700, Tom Rix wrote:
On 9/10/21 1:27 PM, Russ Weight wrote:
On 9/10/21 8:13 AM, Xu Yilun wrote:
On Thu, Sep 09, 2021 at 04:33:01PM -0700, Russ Weight wrote:
Create a sub driver for the FPGA Card BMC in order to support secure
updates. This sub-driver will invoke an instance of the FPGA Image Load
class driver for the image load portion of the update.

This patch creates the MAX10 BMC Secure Update driver and provides sysfs
files for displaying the current root entry hashes for the FPGA static
region, the FPGA PR region, and the MAX10 BMC.

Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
Reviewed-by: Tom Rix <trix@xxxxxxxxxx>
---
v14:
- Changed symbol and text references to reflect the renaming of the
Security Manager Class driver to FPGA Image Load.
v13:
- Updated copyright to 2021
- Updated ABI documentation date and kernel version
- Call updated fpga_sec_mgr_register() and fpga_sec_mgr_unregister()
functions instead of devm_fpga_sec_mgr_create() and
devm_fpga_sec_mgr_register().
v12:
- Updated Date and KernelVersion fields in ABI documentation
v11:
- Added Reviewed-by tag
v10:
- Changed the path expressions in the sysfs documentation to
replace the n3000 reference with something more generic to
accomodate other devices that use the same driver.
v9:
- Rebased to 5.12-rc2 next
- Updated Date and KernelVersion in ABI documentation
v8:
- Previously patch 2/6, otherwise no change
v7:
- Updated Date and KernelVersion in ABI documentation
v6:
- Added WARN_ON() call for (sha_num_bytes / stride) to assert
that the proper count is passed to regmap_bulk_read().
v5:
- No change
v4:
- Moved sysfs files for displaying the root entry hashes (REH)
from the FPGA Security Manager class driver to here. The
m10bmc_reh() and m10bmc_reh_size() functions are removed and
the functionality from these functions is moved into a
show_root_entry_hash() function for displaying the REHs.
- Added ABI documentation for the new sysfs entries:
sysfs-driver-intel-m10-bmc-secure
- Updated the MAINTAINERS file to add the new ABI documentation
file: sysfs-driver-intel-m10-bmc-secure
- Removed unnecessary ret variable from m10bmc_secure_probe()
- Incorporated new devm_fpga_sec_mgr_register() function into
m10bmc_secure_probe() and removed the m10bmc_secure_remove()
function.
v3:
- Changed from "Intel FPGA Security Manager" to FPGA Security Manager"
- Changed: iops -> sops, imgr -> smgr, IFPGA_ -> FPGA_, ifpga_ to fpga_
- Changed "MAX10 BMC Secure Engine driver" to "MAX10 BMC Secure
Update driver"
- Removed wrapper functions (m10bmc_raw_*, m10bmc_sys_*). The
underlying functions are now called directly.
- Changed "_root_entry_hash" to "_reh", with a comment explaining
what reh is.
v2:
- Added drivers/fpga/intel-m10-bmc-secure.c file to MAINTAINERS.
- Switched to GENMASK(31, 16) for a couple of mask definitions.
- Moved MAX10 BMC address and function definitions to a separate
patch.
- Replaced small function-creation macros with explicit function
declarations.
- Removed ifpga_sec_mgr_init() and ifpga_sec_mgr_uinit() functions.
- Adapted to changes in the Intel FPGA Security Manager by splitting
the single call to ifpga_sec_mgr_register() into two function
calls: devm_ifpga_sec_mgr_create() and ifpga_sec_mgr_register().
---
.../testing/sysfs-driver-intel-m10-bmc-secure | 29 ++++
MAINTAINERS | 2 +
drivers/fpga/Kconfig | 11 ++
drivers/fpga/Makefile | 3 +
drivers/fpga/intel-m10-bmc-secure.c | 145 ++++++++++++++++++
5 files changed, 190 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
create mode 100644 drivers/fpga/intel-m10-bmc-secure.c

diff --git a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
new file mode 100644
index 000000000000..363403ce992d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
@@ -0,0 +1,29 @@
+What: /sys/bus/platform/drivers/intel-m10bmc-secure/.../security/sr_root_entry_hash
+Date: Aug 2021
+KernelVersion: 5.15
+Contact: Russ Weight <russell.h.weight@xxxxxxxxx>
+Description: Read only. Returns the root entry hash for the static
+ region if one is programmed, else it returns the
+ string: "hash not programmed". This file is only
+ visible if the underlying device supports it.
+ Format: "0x%x".
+
+What: /sys/bus/platform/drivers/intel-m10bmc-secure/.../security/pr_root_entry_hash
+Date: Aug 2021
+KernelVersion: 5.15
+Contact: Russ Weight <russell.h.weight@xxxxxxxxx>
+Description: Read only. Returns the root entry hash for the partial
+ reconfiguration region if one is programmed, else it
+ returns the string: "hash not programmed". This file
+ is only visible if the underlying device supports it.
+ Format: "0x%x".
+
+What: /sys/bus/platform/drivers/intel-m10bmc-secure/.../security/bmc_root_entry_hash
+Date: Aug 2021
+KernelVersion: 5.15
+Contact: Russ Weight <russell.h.weight@xxxxxxxxx>
+Description: Read only. Returns the root entry hash for the BMC image
+ if one is programmed, else it returns the string:
+ "hash not programmed". This file is only visible if the
+ underlying device supports it.
+ Format: "0x%x".
diff --git a/MAINTAINERS b/MAINTAINERS
index e3fbc1bde9bc..cf93835b4775 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7363,8 +7363,10 @@ M: Russ Weight <russell.h.weight@xxxxxxxxx>
L: linux-fpga@xxxxxxxxxxxxxxx
S: Maintained
F: Documentation/ABI/testing/sysfs-class-fpga-image-load
+F: Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
Should we change the name of the driver? Some keywords like "image load"
or "firmware update" should be in the name.
I considered that. The image-upload functionality is a subset of  this
driver. It also exposes security collateral via sysfs, and the image-load
triggers and power-on-image sysfs files will probably end up in this
driver too.

The current driver name is intel-m10-bmc-secure. Do we need to keep
"intel-m10-bmc" in the name?

intel-m10-bmc-sec-fw-update?
intel-m10-bmc-sec-update?

What do you think? Any other suggestions?
The single word "secure" is quite indistinct to me. I think
intel-m10-bmc-sec-update is much better.

This fine.

Should it move to mfd/ ?

Tom


The prefix intel-m10-bmc-sec is clunky and confuses me because I think of
mfd/intel-m10-bmc.c
The secure update engine is now implemented in MAX10 bmc. The driver
code also assumes it is always a sub device of MAX10 bmc. So my
preference is we keep the prefix.

How about

dfl-image-load ?
There may be several secure update engines for DFL based FPGAs. So we
may be more specific.

Thanks,
Yilun