linux-kernel - Re: [PATCH] cpufreq: acpi: Don't enable boost on policy exit

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAKohponCr6pwgmK+J0WnvY_VZdDhA738JF18L518A2MKJVQLmw@mail.gmail.com>
Date: Sat, 19 Apr 2025 13:24:38 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Nicholas Chin <nic.c3.14@...il.com>, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org, rafael.j.wysocki@...el.com, 
	vincent.guittot@...aro.org, zhenglifeng1@...wei.com
Subject: Re: [PATCH] cpufreq: acpi: Don't enable boost on policy exit

On Sat, 19 Apr 2025 at 00:58, Rafael J. Wysocki <rafael@...nel.org> wrote:

> So it updates policy->boost_enabled in accordance with the current
> setting in the MSR.

Yes.

> IMO it would be better to update the MSR in accordance with
> policy->boost_enabled or users may get confused if their boost
> settings change after a suspend-resume cycle.  Or have I got lost
> completely?

I wrote this patch based on the sync that happens at the end of
cpufreq_online():

        /* Let the per-policy boost flag mirror the cpufreq_driver
boost during init */
        if (cpufreq_driver->set_boost && policy->boost_supported &&
            policy->boost_enabled != cpufreq_boost_enabled()) {
                policy->boost_enabled = cpufreq_boost_enabled();
                ret = cpufreq_driver->set_boost(policy, policy->boost_enabled);
                if (ret) {
                        /* If the set_boost fails, the online
operation is not affected */
                        pr_info("%s: CPU%d: Cannot %s BOOST\n",
__func__, policy->cpu,
                                str_enable_disable(policy->boost_enabled));
                        policy->boost_enabled = !policy->boost_enabled;
                }
        }

So my patch works as the cpufreq core force-syncs the state at init
(pretty much what the driver was doing before).

Though I now wonder if this code (in cpufreq_online()) is really doing
the right thing or not. So if global boost is enabled before suspend with
policy boost being disabled, the policy boost will be enabled on resume.

--
Viresh