From nobody Wed Dec 17 09:44:29 2025 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF38FCDB474 for ; Fri, 20 Oct 2023 15:13:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377666AbjJTPNG (ORCPT ); Fri, 20 Oct 2023 11:13:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57490 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377631AbjJTPNA (ORCPT ); Fri, 20 Oct 2023 11:13:00 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3825BD69 for ; Fri, 20 Oct 2023 08:12:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1697814778; x=1729350778; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Bu2/tizz5ae3ipBcoXAV9deIpKDIFDrWSuBYbHVXXFM=; b=Qd3pJVk2/b7Zc/QCbM8mb9Osn9GW0bL5K6RKNf3P/PK5AS1S4ZwrrXca j+d8N8LdwzR4VQ+Eoxb05gpOJrIXBH4HkVj33URu46bSooRwfxf+2rPf5 LGMao3BsQcyqj0GzOSPH9ALg4ounaZso+VswdQxvZxm/0Nn8CM+3NXXRD 0uOli6JJ2hIPxaZijfGUquukFwZw813df7Pm3zU33pESJhsasVAygYWfy pjp4TxNTRzHN2BJ9cwCdt4cL9Bd+j35IYJNEOEEQ0ugPLP6bloZUTh44U +KsJe0MutvdGNIqxVGqdVkIyiPqTUc0fauNLC/3eQLO7NWJAMLnBO+hxG A==; X-IronPort-AV: E=McAfee;i="6600,9927,10869"; a="376893585" X-IronPort-AV: E=Sophos;i="6.03,239,1694761200"; d="scan'208";a="376893585" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2023 08:12:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10869"; a="761080240" X-IronPort-AV: E=Sophos;i="6.03,239,1694761200"; d="scan'208";a="761080240" Received: from dgutows1-mobl.ger.corp.intel.com (HELO box.shutemov.name) ([10.249.39.237]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2023 08:12:48 -0700 Received: by box.shutemov.name (Postfix, from userid 1000) id F19B010A294; Fri, 20 Oct 2023 18:12:44 +0300 (+03) From: "Kirill A. Shutemov" To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "Rafael J. Wysocki" , Peter Zijlstra , Adrian Hunter , Kuppuswamy Sathyanarayanan , Elena Reshetova , Jun Nakajima , Rick Edgecombe , Tom Lendacky , "Kalra, Ashish" , Sean Christopherson , "Huang, Kai" , Baoquan He , kexec@lists.infradead.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv2 02/13] kernel/cpu: Add support for declaring CPU offlining not supported Date: Fri, 20 Oct 2023 18:12:31 +0300 Message-ID: <20231020151242.1814-3-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231020151242.1814-1-kirill.shutemov@linux.intel.com> References: <20231020151242.1814-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" ACPI MADT doesn't allow to offline CPU after it got woke up. Currently offlining hotplug prevented based on the confidential computing attribute which is set for Intel TDX. But TDX is not the only possible user of the wake up method. Introduce cpu_hotplug_not_supported() that can be called to indicate that CPU offlining should be disabled. This function is going to replace CC_ATTR_HOTPLUG_DISABLED for ACPI MADT. Signed-off-by: Kirill A. Shutemov --- include/linux/cpu.h | 2 ++ kernel/cpu.c | 13 ++++++++++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/include/linux/cpu.h b/include/linux/cpu.h index f19f56501809..97832ced939d 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -132,6 +132,7 @@ extern void cpus_read_lock(void); extern void cpus_read_unlock(void); extern int cpus_read_trylock(void); extern void lockdep_assert_cpus_held(void); +extern void cpu_hotplug_disable_offlining(void); extern void cpu_hotplug_disable(void); extern void cpu_hotplug_enable(void); void clear_tasks_mm_cpumask(int cpu); @@ -147,6 +148,7 @@ static inline void cpus_read_lock(void) { } static inline void cpus_read_unlock(void) { } static inline int cpus_read_trylock(void) { return true; } static inline void lockdep_assert_cpus_held(void) { } +static inline void cpu_hotplug_disable_offlining(void) { } static inline void cpu_hotplug_disable(void) { } static inline void cpu_hotplug_enable(void) { } static inline int remove_cpu(unsigned int cpu) { return -EPERM; } diff --git a/kernel/cpu.c b/kernel/cpu.c index 6de7c6bb74ee..faebee0050a2 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -484,6 +484,8 @@ static int cpu_hotplug_disabled; =20 DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock); =20 +static bool cpu_hotplug_offline_disabled; + void cpus_read_lock(void) { percpu_down_read(&cpu_hotplug_lock); @@ -543,6 +545,14 @@ static void lockdep_release_cpus_lock(void) rwsem_release(&cpu_hotplug_lock.dep_map, _THIS_IP_); } =20 +/* Declare CPU offlining not supported */ +void cpu_hotplug_disable_offlining(void) +{ + cpu_maps_update_begin(); + cpu_hotplug_offline_disabled =3D true; + cpu_maps_update_done(); +} + /* * Wait for currently running CPU hotplug operations to complete (if any) = and * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' prot= ects @@ -1507,7 +1517,8 @@ static int cpu_down_maps_locked(unsigned int cpu, enu= m cpuhp_state target) * If the platform does not support hotplug, report it explicitly to * differentiate it from a transient offlining failure. */ - if (cc_platform_has(CC_ATTR_HOTPLUG_DISABLED)) + if (cc_platform_has(CC_ATTR_HOTPLUG_DISABLED) || + cpu_hotplug_offline_disabled) return -EOPNOTSUPP; if (cpu_hotplug_disabled) return -EBUSY; --=20 2.41.0