linux-kernel - Re: [PATCH 0/4] ACPI: CPPC: Fixes to limit actions to online CPUs

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: <1f6c7144-9b4e-4252-b62e-71c348f11827@kernel.org>
Date: Wed, 5 Nov 2025 10:00:25 -0600
From: "Mario Limonciello (AMD) (kernel.org)" <superm1@...nel.org>
To: "Gautham R. Shenoy" <gautham.shenoy@....com>,
 "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 Yunhui Cui <cuiyunhui@...edance.com>, Jeremy Linton <jeremy.linton@....com>,
 Viresh Kumar <viresh.kumar@...aro.org>,
 Ionela Voinescu <ionela.voinescu@....com>
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
 Christopher Harris <chris.harris79@...il.com>, linux-pm@...r.kernel.org
Subject: Re: [PATCH 0/4] ACPI: CPPC: Fixes to limit actions to online CPUs

On 11/5/2025 8:38 AM, Gautham R. Shenoy wrote:
> Hello,
> 
> Christopher Harris reported a regression between v6.10 to v6.11 that
> the amd-pstate driver failed to load even when the commandline had
> "amd_pstate=passive"
> (https://lore.kernel.org/lkml/CAM+eXpdDT7KjLV0AxEwOLkSJ2QtrsvGvjA2cCHvt1d0k2_C4Cw@mail.gmail.com/)
> 
> On debugging the issue it was observed that when the commandline
> contains "nosmt=force", the CPPC code fails when performing certain
> checks such as checking for the presence of preferred cores and
> validity of the _CPC object since it iterates through all "present"
> CPUs while the object state was populated only for "online" CPUs.
> 
> This patchset contains fixes to address this issue.
> 
> The first two patches in the series address the issue reported by
> Chris.
> 
> Patches 3 and 4 harden the code in a couple of more functions which
> iterated through the present CPUs when it is more apt to restrict the
> operations to online CPUs
> 
> 
> 
> Gautham R. Shenoy (4):
>    ACPI: CPPC: Detect preferred core availability on online CPUs
>    ACPI: CPPC: Check _CPC validity for only the online CPUs
>    ACPI: CPPC: Perform fast check switch only for online CPUs
>    ACPI: CPPC: Limit perf ctrs in PCC check only to online CPUs
> 
>   arch/x86/kernel/acpi/cppc.c | 2 +-
>   drivers/acpi/cppc_acpi.c    | 6 +++---
>   2 files changed, 4 insertions(+), 4 deletions(-)
> 

The series looks good to me.

Reviewed-by: Mario Limonciello (AMD) <superm1@...nel.org>

But I would say I noticed we are also using for_each_present_cpu() in 
amd-pstate with amd_pstate_change_mode_without_dvr_change().

Should that also get a similar change?