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Message-ID: <20220517041310.GA40711@yilunxu-OptiPlex-7050>
Date: Tue, 17 May 2022 12:13:10 +0800
From: Xu Yilun <yilun.xu@...el.com>
To: Russ Weight <russell.h.weight@...el.com>
Cc: mdf@...nel.org, hao.wu@...el.com, lee.jones@...aro.org,
linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org,
trix@...hat.com, marpagan@...hat.com, lgoncalv@...hat.com,
matthew.gerlach@...ux.intel.com,
basheer.ahmed.muddebihal@...el.com, tianfei.zhang@...el.com
Subject: Re: [PATCH v20 3/5] fpga: m10bmc-sec: expose max10 flash update count
On Mon, May 16, 2022 at 04:49:39PM -0700, Russ Weight wrote:
> Extend the MAX10 BMC Secure Update driver to provide a sysfs file to
> expose the flash update count.
>
> Signed-off-by: Russ Weight <russell.h.weight@...el.com>
> Reviewed-by: Tom Rix <trix@...hat.com>
> ---
> v20:
> - No change
> v19:
> - Change "card bmc" naming back to "m10 bmc" naming to be consistent
> with the parent driver.
> v18:
> - No change
> v17:
> - Update the Date and KernelVersion for the ABI documentation to Jul 2022
> and 5.19 respectively.
> - Change "m10bmc" in symbol names to "cardbmc" to reflect the fact that the
> future devices will not necessarily use the MAX10.
> v16:
> - No Change
> v15:
> - Updated the Dates and KernelVersions in the ABI documentation
> v14:
> - No change
> v13:
> - Updated ABI documentation date and kernel version
> v12:
> - Updated Date and KernelVersion fields in ABI documentation
> v11:
> - No change
> v10:
> - Changed the path expression 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 3/6, otherwise no change
> v7:
> - Updated Date and KernelVersion in ABI documentation
> v6:
> - Changed flash_count_show() parameter list to achieve
> reverse-christmas tree format.
> - Added WARN_ON() call for (FLASH_COUNT_SIZE / stride) to ensure
> that the proper count is passed to regmap_bulk_read().
> v5:
> - Renamed sysfs node user_flash_count to flash_count and updated the
> sysfs documentation accordingly.
> v4:
> - Moved the sysfs file for displaying the flash count from the
> FPGA Security Manager class driver to here. The
> m10bmc_user_flash_count() function is removed and the
> functionality is moved into a user_flash_count_show()
> function.
> - Added ABI documentation for the new sysfs entry
> v3:
> - 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.
> v2:
> - Renamed get_qspi_flash_count() to m10bmc_user_flash_count()
> - Minor code cleanup per review comments
> - Added m10bmc_ prefix to functions in m10bmc_iops structure
> ---
> .../sysfs-driver-intel-m10-bmc-sec-update | 8 +++++
> drivers/fpga/intel-m10-bmc-sec-update.c | 36 +++++++++++++++++++
> 2 files changed, 44 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-sec-update b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-sec-update
> index 2bb271695e14..1132e39b2125 100644
> --- a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-sec-update
> +++ b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-sec-update
> @@ -27,3 +27,11 @@ Description: Read only. Returns the root entry hash for the BMC image
> "hash not programmed". This file is only visible if the
> underlying device supports it.
> Format: string.
> +
> +What: /sys/bus/platform/drivers/intel-m10bmc-sec-update/.../security/flash_count
> +Date: Jul 2022
> +KernelVersion: 5.19
> +Contact: Russ Weight <russell.h.weight@...el.com>
> +Description: Read only. Returns number of times the secure update
> + staging area has been flashed.
> + Format: "%u".
> diff --git a/drivers/fpga/intel-m10-bmc-sec-update.c b/drivers/fpga/intel-m10-bmc-sec-update.c
> index f9f39d2cfe5b..3f183202de3b 100644
> --- a/drivers/fpga/intel-m10-bmc-sec-update.c
> +++ b/drivers/fpga/intel-m10-bmc-sec-update.c
> @@ -78,7 +78,43 @@ DEVICE_ATTR_SEC_REH_RO(bmc, BMC_PROG_MAGIC, BMC_PROG_ADDR, BMC_REH_ADDR);
> DEVICE_ATTR_SEC_REH_RO(sr, SR_PROG_MAGIC, SR_PROG_ADDR, SR_REH_ADDR);
> DEVICE_ATTR_SEC_REH_RO(pr, PR_PROG_MAGIC, PR_PROG_ADDR, PR_REH_ADDR);
>
> +#define FLASH_COUNT_SIZE 4096 /* count stored as inverted bit vector */
> +
> +static ssize_t flash_count_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct m10bmc_sec *sec = dev_get_drvdata(dev);
> + unsigned int stride, num_bits;
> + u8 *flash_buf;
> + int cnt, ret;
> +
> + stride = regmap_get_reg_stride(sec->m10bmc->regmap);
> + num_bits = FLASH_COUNT_SIZE * 8;
> +
> + flash_buf = kmalloc(FLASH_COUNT_SIZE, GFP_KERNEL);
> + if (!flash_buf)
> + return -ENOMEM;
> +
> + WARN_ON(FLASH_COUNT_SIZE % stride);
The same concern here. Stop users from getting the broken value.
> + ret = regmap_bulk_read(sec->m10bmc->regmap, STAGING_FLASH_COUNT,
> + flash_buf, FLASH_COUNT_SIZE / stride);
> + if (ret) {
> + dev_err(sec->dev,
> + "failed to read flash count: %x cnt %x: %d\n",
> + STAGING_FLASH_COUNT, FLASH_COUNT_SIZE / stride, ret);
> + goto exit_free;
> + }
> + cnt = num_bits - bitmap_weight((unsigned long *)flash_buf, num_bits);
> +
> +exit_free:
> + kfree(flash_buf);
> +
> + return ret ? : sysfs_emit(buf, "%u\n", cnt);
> +}
> +static DEVICE_ATTR_RO(flash_count);
> +
> static struct attribute *m10bmc_security_attrs[] = {
> + &dev_attr_flash_count.attr,
> &dev_attr_bmc_root_entry_hash.attr,
> &dev_attr_sr_root_entry_hash.attr,
> &dev_attr_pr_root_entry_hash.attr,
> --
> 2.25.1
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