From patchwork Wed Apr 21 17:40:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 425544 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 811C4C433B4 for ; Wed, 21 Apr 2021 17:41:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F7DF61430 for ; Wed, 21 Apr 2021 17:41:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243206AbhDURld (ORCPT ); Wed, 21 Apr 2021 13:41:33 -0400 Received: from cloudserver094114.home.pl ([79.96.170.134]:51594 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243098AbhDURlc (ORCPT ); Wed, 21 Apr 2021 13:41:32 -0400 Received: from localhost (127.0.0.1) (HELO v370.home.net.pl) by /usr/run/smtp (/usr/run/postfix/private/idea_relay_lmtp) via UNIX with SMTP (IdeaSmtpServer 2.0.5) id 31b07786e97dcc5f; Wed, 21 Apr 2021 19:40:57 +0200 Received: from kreacher.localnet (89-64-80-44.dynamic.chello.pl [89.64.80.44]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by v370.home.net.pl (Postfix) with ESMTPSA id A8DFF669387; Wed, 21 Apr 2021 19:40:56 +0200 (CEST) From: "Rafael J. Wysocki" To: Linux PM Cc: Srinivas Pandruvada , LKML Subject: [PATCH] cpufreq: intel_pstate: Use HWP if enabled by platform firmware Date: Wed, 21 Apr 2021 19:40:56 +0200 Message-ID: <2602702.mvXUDI8C0e@kreacher> MIME-Version: 1.0 X-CLIENT-IP: 89.64.80.44 X-CLIENT-HOSTNAME: 89-64-80-44.dynamic.chello.pl X-VADE-SPAMSTATE: clean X-VADE-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeduledrvddtkedguddujecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfjqffogffrnfdpggftiffpkfenuceurghilhhouhhtmecuudehtdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephffvufffkfgggfgtsehtufertddttdejnecuhfhrohhmpedftfgrfhgrvghlucflrdcuhgihshhotghkihdfuceorhhjfiesrhhjfiihshhotghkihdrnhgvtheqnecuggftrfgrthhtvghrnhephfegtdffjeehkeegleejveevtdeugfffieeijeduuddtkefgjedvheeujeejtedvnecukfhppeekledrieegrdektddrgeegnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepkeelrdeigedrkedtrdeggedphhgvlhhopehkrhgvrggthhgvrhdrlhhotggrlhhnvghtpdhmrghilhhfrhhomhepfdftrghfrggvlhculfdrucghhihsohgtkhhifdcuoehrjhifsehrjhifhihsohgtkhhirdhnvghtqedprhgtphhtthhopehlihhnuhigqdhpmhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehsrhhinhhivhgrshdrphgrnhgurhhuvhgruggrsehlihhnuhigrdhinhhtvghlrdgtohhmpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhg X-DCC--Metrics: v370.home.net.pl 1024; Body=3 Fuz1=3 Fuz2=3 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Rafael J. Wysocki It turns out that there are systems where HWP is enabled during initialization by the platform firmware (BIOS), but HWP EPP support is not advertised. After commit 7aa1031223bc ("cpufreq: intel_pstate: Avoid enabling HWP if EPP is not supported") intel_pstate refuses to use HWP on those systems, but the fallback PERF_CTL interface does not work on them either because of enabled HWP, and once enabled, HWP cannot be disabled. Consequently, the users of those systems cannot control CPU performance scaling. Address this issue by making intel_pstate use HWP unconditionally if it is enabled already when the driver starts. Fixes: 7aa1031223bc ("cpufreq: intel_pstate: Avoid enabling HWP if EPP is not supported") Reported-by: Srinivas Pandruvada Tested-by: Srinivas Pandruvada Signed-off-by: Rafael J. Wysocki Cc: 5.9+ # 5.9+ --- drivers/cpufreq/intel_pstate.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) Index: linux-pm/drivers/cpufreq/intel_pstate.c =================================================================== --- linux-pm.orig/drivers/cpufreq/intel_pstate.c +++ linux-pm/drivers/cpufreq/intel_pstate.c @@ -3229,6 +3229,14 @@ static const struct x86_cpu_id hwp_suppo {} }; +static bool intel_pstate_hwp_is_enabled(void) +{ + u64 value; + + rdmsrl(MSR_PM_ENABLE, value); + return !!(value & 0x1); +} + static int __init intel_pstate_init(void) { const struct x86_cpu_id *id; @@ -3247,8 +3255,12 @@ static int __init intel_pstate_init(void * Avoid enabling HWP for processors without EPP support, * because that means incomplete HWP implementation which is a * corner case and supporting it is generally problematic. + * + * If HWP is enabled already, though, there is no choice but to + * deal with it. */ - if (!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) { + if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) || + intel_pstate_hwp_is_enabled()) { hwp_active++; hwp_mode_bdw = id->driver_data; intel_pstate.attr = hwp_cpufreq_attrs;