From patchwork Fri Jan 10 11:59:50 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patryk Wlazlyn X-Patchwork-Id: 857443 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C10320C024; Fri, 10 Jan 2025 12:00:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736510408; cv=none; b=aWIQisPAIFdWWmH7usvLsTbmi04r22/GPJTWrtPwr+YstDVoGG+Dqjo2SNaez83z6d7J3NnMPiJurPedwq+sxlDGkGCJSfXFvDlxx/dhHE/Gg7X4jbA/XyKgWwCOOQAK2WSBkDAHyt20rysj17EZmpo0uf+C4Mn3xFVcH0jLvh4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736510408; c=relaxed/simple; bh=hiq3NjmqUPpOUOzdilX8riGPqCTp70rQ6V6K84wJDUY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YCOe3UpZsDmxQYp0bV3SUk1/l9kXpjTlH1UPRhZseOrzHBeh21ko52TTa9s83VZqAu8w1R+Y4xyllYQo/cf0vWuztVlLUTdKlw7ZeyI7QZkQDUzVKqDSSAqZ83zZjUArXizh3nJbDsiH3qjOtWK9NVCFGbAFfASxezmBF+Q0hZQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=j4w6dVzj; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="j4w6dVzj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1736510406; x=1768046406; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=hiq3NjmqUPpOUOzdilX8riGPqCTp70rQ6V6K84wJDUY=; b=j4w6dVzjsXCstnMvtqzEW15pk7yUyjUFwUJDJvelh9HWDUmwtNCogu+t whGNBQh6Fzu/YzcLNhjYbKeZ7ginA3moqroUeA2CedMcV/yrqb6uymtW0 ho7AqivJt7nb5f/eYPS4e60WEzPXkY3TsYsOSjkCSyc42sSCLJv4gXzP1 jQCooVU6q+kUQ5iYlyw4CtbKc/NsxBPTFZ39ZvJwCaYOV1zPQwvRztkfa 209E6z9yATNuZ4qtfvrytA52pDcTbrLL9IOBnue55TPZBiHCxJtETZ5Ux MTuVBZbFit5Nk1gEDz4dYKNsAuqNPSRpjeQ087+fcvqsXBfd4CUDVTeEz Q==; X-CSE-ConnectionGUID: NZPneuZ9TL+4nlV5yTALiQ== X-CSE-MsgGUID: gcjVas+QTS67iemoZGgwFQ== X-IronPort-AV: E=McAfee;i="6700,10204,11310"; a="40743770" X-IronPort-AV: E=Sophos;i="6.12,303,1728975600"; d="scan'208";a="40743770" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jan 2025 04:00:06 -0800 X-CSE-ConnectionGUID: xtLEIwiHQNS2f4eZ9clkBQ== X-CSE-MsgGUID: QsGe5Bc5RGS4okEnNltXxw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,303,1728975600"; d="scan'208";a="108635969" Received: from ksztyber-mobl2.ger.corp.intel.com (HELO localhost.localdomain) ([10.245.244.160]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jan 2025 04:00:03 -0800 From: Patryk Wlazlyn To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rafael.j.wysocki@intel.com, len.brown@intel.com, artem.bityutskiy@linux.intel.com, dave.hansen@linux.intel.com, patryk.wlazlyn@linux.intel.com Subject: [PATCH v9 1/4] x86/smp: Allow calling mwait_play_dead with an arbitrary hint Date: Fri, 10 Jan 2025 12:59:50 +0100 Message-ID: <20250110115953.6058-2-patryk.wlazlyn@linux.intel.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250110115953.6058-1-patryk.wlazlyn@linux.intel.com> References: <20250110115953.6058-1-patryk.wlazlyn@linux.intel.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Introduce a helper function to allow offlined CPUs to enter FFh idle states with a specific MWAIT hint. The new helper will be used in subsequent patches by the acpi_idle and intel_idle drivers. No functional change intended. Signed-off-by: Patryk Wlazlyn Reviewed-by: Gautham R. Shenoy --- arch/x86/include/asm/smp.h | 3 ++ arch/x86/kernel/smpboot.c | 90 ++++++++++++++++++++------------------ 2 files changed, 51 insertions(+), 42 deletions(-) diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index ca073f40698f..dfd09a1e09bf 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -114,6 +114,7 @@ void wbinvd_on_cpu(int cpu); int wbinvd_on_all_cpus(void); void smp_kick_mwait_play_dead(void); +void mwait_play_dead(unsigned int hint); void native_smp_send_reschedule(int cpu); void native_send_call_func_ipi(const struct cpumask *mask); @@ -164,6 +165,8 @@ static inline struct cpumask *cpu_llc_shared_mask(int cpu) { return (struct cpumask *)cpumask_of(0); } + +static inline void mwait_play_dead(unsigned int eax_hint) { } #endif /* CONFIG_SMP */ #ifdef CONFIG_DEBUG_NMI_SELFTEST diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index b5a8f0891135..8a3545c2cae9 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1272,13 +1272,57 @@ void play_dead_common(void) local_irq_disable(); } +void __noreturn mwait_play_dead(unsigned int eax_hint) +{ + struct mwait_cpu_dead *md = this_cpu_ptr(&mwait_cpu_dead); + + /* Set up state for the kexec() hack below */ + md->status = CPUDEAD_MWAIT_WAIT; + md->control = CPUDEAD_MWAIT_WAIT; + + wbinvd(); + + while (1) { + /* + * The CLFLUSH is a workaround for erratum AAI65 for + * the Xeon 7400 series. It's not clear it is actually + * needed, but it should be harmless in either case. + * The WBINVD is insufficient due to the spurious-wakeup + * case where we return around the loop. + */ + mb(); + clflush(md); + mb(); + __monitor(md, 0, 0); + mb(); + __mwait(eax_hint, 0); + + if (READ_ONCE(md->control) == CPUDEAD_MWAIT_KEXEC_HLT) { + /* + * Kexec is about to happen. Don't go back into mwait() as + * the kexec kernel might overwrite text and data including + * page tables and stack. So mwait() would resume when the + * monitor cache line is written to and then the CPU goes + * south due to overwritten text, page tables and stack. + * + * Note: This does _NOT_ protect against a stray MCE, NMI, + * SMI. They will resume execution at the instruction + * following the HLT instruction and run into the problem + * which this is trying to prevent. + */ + WRITE_ONCE(md->status, CPUDEAD_MWAIT_KEXEC_HLT); + while(1) + native_halt(); + } + } +} + /* * We need to flush the caches before going to sleep, lest we have * dirty data in our caches when we come back up. */ -static inline void mwait_play_dead(void) +static inline void mwait_play_dead_cpuid_hint(void) { - struct mwait_cpu_dead *md = this_cpu_ptr(&mwait_cpu_dead); unsigned int eax, ebx, ecx, edx; unsigned int highest_cstate = 0; unsigned int highest_subcstate = 0; @@ -1316,45 +1360,7 @@ static inline void mwait_play_dead(void) (highest_subcstate - 1); } - /* Set up state for the kexec() hack below */ - md->status = CPUDEAD_MWAIT_WAIT; - md->control = CPUDEAD_MWAIT_WAIT; - - wbinvd(); - - while (1) { - /* - * The CLFLUSH is a workaround for erratum AAI65 for - * the Xeon 7400 series. It's not clear it is actually - * needed, but it should be harmless in either case. - * The WBINVD is insufficient due to the spurious-wakeup - * case where we return around the loop. - */ - mb(); - clflush(md); - mb(); - __monitor(md, 0, 0); - mb(); - __mwait(eax, 0); - - if (READ_ONCE(md->control) == CPUDEAD_MWAIT_KEXEC_HLT) { - /* - * Kexec is about to happen. Don't go back into mwait() as - * the kexec kernel might overwrite text and data including - * page tables and stack. So mwait() would resume when the - * monitor cache line is written to and then the CPU goes - * south due to overwritten text, page tables and stack. - * - * Note: This does _NOT_ protect against a stray MCE, NMI, - * SMI. They will resume execution at the instruction - * following the HLT instruction and run into the problem - * which this is trying to prevent. - */ - WRITE_ONCE(md->status, CPUDEAD_MWAIT_KEXEC_HLT); - while(1) - native_halt(); - } - } + mwait_play_dead(eax); } /* @@ -1407,7 +1413,7 @@ void native_play_dead(void) play_dead_common(); tboot_shutdown(TB_SHUTDOWN_WFS); - mwait_play_dead(); + mwait_play_dead_cpuid_hint(); if (cpuidle_play_dead()) hlt_play_dead(); }