From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8ADFC433EF for ; Thu, 18 Nov 2021 13:15:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B292761547 for ; Thu, 18 Nov 2021 13:15:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230188AbhKRNSG (ORCPT ); Thu, 18 Nov 2021 08:18:06 -0500 Received: from mail-oi1-f173.google.com ([209.85.167.173]:38631 "EHLO mail-oi1-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229461AbhKRNSF (ORCPT ); Thu, 18 Nov 2021 08:18:05 -0500 Received: by mail-oi1-f173.google.com with SMTP id r26so14178447oiw.5; Thu, 18 Nov 2021 05:15:05 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=52oLeLHIWh1xHoLlS9D+Tl+qwNv+fGRWrOK+8Oypj1U=; b=REfpOoFxpGY5M3VBg47a6Tb9xt069wzIzy/fm34BS8yW/HJn8TDVi1coilsUfJ0F6d nBNov5EBGiOQLI0QynHtjZAojhb6sylMpmjL6uZPgxw+tE4tYK4MeON+AooGuJJjF6UB ZQ0mNluq1Dgxn5NzEN++pfxe9/x3FNqDnDeoHWPR0ak2djiQMuUrc2YP38PfZ2MG37iA YVwH+/dXC5UdWBWW1EK5fOl6Toor2mIRfCk8b5gpdz1FkJ1WZTt6KEOs9tDGtNCPwUKL gyVE/C8eMunZ0gfWM2RyRVqg9Y988tJK5k5C/B0lJezIeXLxAdavZ/yElKqT26NGvZaD WU8w== X-Gm-Message-State: AOAM532q7Md2an+q3vI8ALJ+iUYu61PwV+NxMX9cazWTbTsuMMa0E6lE 07SeASaVpkCXqQYDyyz1i8hw/t0PhWuyh2ngxsjbi6DFBDs= X-Google-Smtp-Source: ABdhPJznVs8RdU58nNdpoEVh7Va5XIjxAah0DS4EqoY0YLpBdNkaHrgSESoA4MuVtUS6Hp8Sn4vadDFuOUkO5r1REHg= X-Received: by 2002:a05:6808:14c3:: with SMTP id f3mr7709090oiw.51.1637241304764; Thu, 18 Nov 2021 05:15:04 -0800 (PST) MIME-Version: 1.0 References: <20211118124553.599419-1-kai.heng.feng@canonical.com> In-Reply-To: <20211118124553.599419-1-kai.heng.feng@canonical.com> From: "Rafael J. Wysocki" Date: Thu, 18 Nov 2021 14:14:54 +0100 Message-ID: Subject: Re: [PATCH] cpufreq: intel_pstate: Avoid using CPPC when ACPI CPC is not valid To: Kai-Heng Feng Cc: Srinivas Pandruvada , Len Brown , "Rafael J. Wysocki" , Viresh Kumar , "open list:INTEL PSTATE DRIVER" , open list Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 18, 2021 at 1:46 PM Kai-Heng Feng wrote: > > If ACPI CPC is not valid, dereference cpc_desc in cppc_get_perf() causes > a NULL pointer dereference. So avoid using CPPC for that scenario. > > Fixes: 46573fd6369f ("cpufreq: intel_pstate: hybrid: Rework HWP calibration") > Signed-off-by: Kai-Heng Feng The bug is real, but it is not in intel_pstate. cppc_get_perf() should return an error in that case. Let me fix this. > --- > drivers/cpufreq/intel_pstate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > index 815df3daae9df..24c7d705b99b6 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -3369,7 +3369,7 @@ static int __init intel_pstate_init(void) > if (!default_driver) > default_driver = &intel_pstate; > > - if (boot_cpu_has(X86_FEATURE_HYBRID_CPU)) > + if (boot_cpu_has(X86_FEATURE_HYBRID_CPU) && acpi_cpc_valid()) > intel_pstate_cppc_set_cpu_scaling(); > > goto hwp_cpu_matched; > -- > 2.32.0 >