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Date: Mon, 18 Sep 2023 11:23:16 -0400
From: "Mark Pearson" <mpearson-lenovo@...ebb.ca>
To: "Hans de Goede" <hdegoede@...hat.com>,
"Andy Shevchenko" <andriy.shevchenko@...el.com>
Cc: "markgross@...nel.org" <markgross@...nel.org>,
"platform-driver-x86@...r.kernel.org"
<platform-driver-x86@...r.kernel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] platform/x86: think-lmi: Add bulk save feature
Thanks Andy for the review
On Mon, Sep 18, 2023, at 10:07 AM, Hans de Goede wrote:
> Hi,
>
> On 9/18/23 15:57, Andy Shevchenko wrote:
>> On Wed, Sep 06, 2023 at 08:13:14AM -0400, Mark Pearson wrote:
>>> On Lenovo platforms there is a limitation in the number of times an
>>> attribute can be saved. This is an architectural limitation and it limits
>>> the number of attributes that can be modified to 48.
>>> A solution for this is instead of the attribute being saved after every
>>> modification allow a user to bulk set the attributes and then trigger a
>>> final save. This allows unlimited attributes.
>>>
>>> This patch introduces a save_settings attribute that can be configured to
>>> either single or bulk mode by the user.
>>> Single mode is the default but customers who want to avoid the 48
>>> attribute limit can enable bulk mode.
>>>
>>> Displaying the save_settings attribute will display the enabled mode.
>>>
>>> When in bulk mode writing 'save' to the save_settings attribute will
>>> trigger a save. Once this has been done a reboot is required before more
>>> attributes can be modified.
>>
>> ...
>>
>>> +Date: August 2023
>>> +KernelVersion: 6.5
>>
>> This is obviously incorrect (outdated) information.
>
> Mark can you please submit a follow up patch fixing this.
So I assume I put 6.6 in here? Or will it be 6.7?
>
>>
>> ...
>>
>>> +static const char * const save_mode_strings[] = {
>>> + [TLMI_SAVE_SINGLE] = "single",
>>> + [TLMI_SAVE_BULK] = "bulk",
>>> + [TLMI_SAVE_SAVE] = "save"
>>
>> Missing comma.
>
> Fixing this retro-actively is not really useful, if we
> ever need an extra entry we can deal with the churn then.
As I'm making other changes I assume I address this one too.
>
>>
>>> +};
>>
>> ...
>>
>>> +static ssize_t save_settings_show(struct kobject *kobj, struct kobj_attribute *attr,
>>> + char *buf)
>>> +{
>>> + /* Check that setting is valid */
>>> + if (WARN_ON((tlmi_priv.save_mode < TLMI_SAVE_SINGLE) ||
>>> + (tlmi_priv.save_mode > TLMI_SAVE_BULK)))
>>> + return -EIO;
>>> + return sprintf(buf, "%s\n", save_mode_strings[tlmi_priv.save_mode]);
>>
>> According to the documentation it must be sysfs_emit() if I'm not missing
>> anything here.
>
> Yes switching to sysfs_emit() here in the followup patch would be good.
Ack
>
>>
>>> +}
>>
>> ...
>>
>>> +static ssize_t save_settings_store(struct kobject *kobj, struct kobj_attribute *attr,
>>> + const char *buf, size_t count)
>>> +{
>>> + char *auth_str = NULL;
>>> + int ret = 0;
>>> + int cmd;
>>> +
>>> + cmd = sysfs_match_string(save_mode_strings, buf);
>>> +
>>> + /* Use lock in case multiple WMI operations needed */
>>> + mutex_lock(&tlmi_mutex);
>>> +
>>> + switch (cmd) {
>>> + case TLMI_SAVE_SINGLE:
>>> + case TLMI_SAVE_BULK:
>>> + tlmi_priv.save_mode = cmd;
>>> + goto out;
>>> + case TLMI_SAVE_SAVE:
>>> + /* Check if supported*/
>>> + if ((!tlmi_priv.can_set_bios_settings) ||
>>> + (tlmi_priv.save_mode == TLMI_SAVE_SINGLE)) {
>>> + ret = -EOPNOTSUPP;
>>> + goto out;
>>> + }
>>> + /* Check there is actually something to save */
>>> + if (!tlmi_priv.save_required) {
>>> + ret = -ENOENT;
>>> + goto out;
>>> + }
>>> + /* Check if certificate authentication is enabled and active */
>>> + if (tlmi_priv.certificate_support && tlmi_priv.pwd_admin->cert_installed) {
>>> + if (!tlmi_priv.pwd_admin->signature ||
>>> + !tlmi_priv.pwd_admin->save_signature) {
>>> + ret = -EINVAL;
>>> + goto out;
>>> + }
>>> + ret = tlmi_simple_call(LENOVO_SAVE_BIOS_SETTING_CERT_GUID,
>>> + tlmi_priv.pwd_admin->save_signature);
>>> + if (ret)
>>> + goto out;
>>> + } else if (tlmi_priv.opcode_support) {
>>> + if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
>>> + ret = tlmi_opcode_setting("WmiOpcodePasswordAdmin",
>>> + tlmi_priv.pwd_admin->password);
>>> + if (ret)
>>> + goto out;
>>> + }
>>> + ret = tlmi_save_bios_settings("");
>>> + } else { /* old non-opcode based authentication method (deprecated) */
>>> + if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
>>> + auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;",
>>> + tlmi_priv.pwd_admin->password,
>>> + encoding_options[tlmi_priv.pwd_admin->encoding],
>>> + tlmi_priv.pwd_admin->kbdlang);
>>> + if (!auth_str) {
>>> + ret = -ENOMEM;
>>> + goto out;
>>> + }
>>> + }
>>> +
>>> + if (auth_str)
>>> + ret = tlmi_save_bios_settings(auth_str);
>>> + else
>>> + ret = tlmi_save_bios_settings("");
>>> + }
>>> + tlmi_priv.save_required = false;
>>> + tlmi_priv.reboot_required = true;
>>> +
>>> + if (!ret && !tlmi_priv.pending_changes) {
>>> + tlmi_priv.pending_changes = true;
>>> + /* let userland know it may need to check reboot pending again */
>>> + kobject_uevent(&tlmi_priv.class_dev->kobj, KOBJ_CHANGE);
>>> + }
>>> + break;
>>
>>> + default:
>>> + ret = -EINVAL;
>>> + }
>>
>> Missing break; and actually no need to do this part under the lock, besides
>> that it shadows an error code, that said this should be
>>
>> cmd = sysfs_match_string(...);
>> if (cmd < 0)
>> return cmd;
>>
>>
>>> +out:
>>> + mutex_unlock(&tlmi_mutex);
>>> + kfree(auth_str);
>>> + return ret ?: count;
>>
>> You can switch the driver to use cleanup.h at some point.
>>
>>> +}
>>
Ack - thanks for the notes.
>> ...
>>
>>> +/* There are a limit on the number of WMI operations you can do if you use
>>> + * the default implementation of saving on every set. This is due to a
>>> + * limitation in EFI variable space used.
>>> + * Have a 'bulk save' mode where you can manually trigger the save, and can
>>> + * therefore set unlimited variables - for users that need it.
>>> + */
>>
>> /*
>> * This is wrong multi-line comment style. This one
>> * is used solely in net subsystem.
>> */
>>
>
> Good catch, Mark can you fix this one too please ?
>
Will do - not sure why I did that in the first place (it's a habit from a looong time ago that came back. Sigh).
Thanks!
Mark
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