linux-kernel - Re: [PATCH] acpi-cpufreq: Fix max-frequency computation

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] [day] [month] [year] [list]

Message-ID: <CAJZ5v0iA-mV=unGYsxYhcG_gRZE3VRhNzCB=-9_Lbem8D-z_uw@mail.gmail.com>
Date: Tue, 14 Jan 2025 21:12:12 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Mario Limonciello <mario.limonciello@....com>, "Gautham R. Shenoy" <gautham.shenoy@....com>
Cc: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>, Viresh Kumar <viresh.kumar@...aro.org>, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Adam Clark <Adam.Clark@....com>
Subject: Re: [PATCH] acpi-cpufreq: Fix max-frequency computation

On Mon, Jan 13, 2025 at 3:23 PM Mario Limonciello
<mario.limonciello@....com> wrote:
>
> On 1/12/2025 22:41, Gautham R. Shenoy wrote:
> > commit 3c55e94c0ade ("cpufreq: ACPI: Extend frequency tables to cover
> > boost frequencies") introduces an assumption in
> > acpi_cpufreq_cpu_init() that the first entry in the P-state table is
> > the nominal frequency. This assumption is incorrect. The frequency
> > corresponding to the P0 P-State need not be the same as the nominal
> > frequency advertised via CPPC.
> >
> > Since the driver is using the CPPC.highest_perf and CPPC.nominal_perf
> > to compute the boost-ratio, it makes sense to use CPPC.nominal_freq to
> > compute the max-frequency. CPPC.nominal_freq is advertised on
> > platforms supporting CPPC revisions 3 or higher.
> >
> > Hence, fallback to using the first entry in the P-State table only on
> > platforms that do not advertise CPPC.nominal_freq.
> >
> > Fixes: 3c55e94c0ade ("cpufreq: ACPI: Extend frequency tables to cover boost frequencies")
> > Tested-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
> > Signed-off-by: Gautham R. Shenoy <gautham.shenoy@....com>
>
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>

Applied as 6.14 material, thanks!