From nobody Sun Dec 28 23:13:31 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 061A9C10DCE for ; Tue, 5 Dec 2023 00:45:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233055AbjLEAp0 (ORCPT ); Mon, 4 Dec 2023 19:45:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229703AbjLEApY (ORCPT ); Mon, 4 Dec 2023 19:45:24 -0500 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09DFAC4 for ; Mon, 4 Dec 2023 16:45:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1701737128; x=1733273128; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=TlUbH+K6pjEWmV+sTKQ2Oh1pOAL04QaVsgJCWqheRjc=; b=J/fVbHYlQhTEqwyzPnpJW8B6yBFbsBl9U4NtXk69fH6O8ecuHLHtrGk1 Lc3CBUDPI7mNBdM9wdMRcS7ki1j7oSw6H6iHUqbmdS3H2kvXC1yW6HUtl u2noANOHbV0OgyUGSURoIVIswDEzM0wi2OlJZGM4bS0WsU9CUAZHvKGYo mUjLXFpDR4kaMfDvzXnITRmw7hES3pD8/jUiE/B30gAmpgGvhys/AIOnP 6yii4bBysjHmzdQQW7Hg0GARowWtywLBDVfA4/8ZK92v66CXjuOWmOa8Y n/iTV84g7Ma+4cSOVmiHyO3zuJ6FEl33bxHHgIs37g+XFnsgWltXq8oA7 w==; X-IronPort-AV: E=McAfee;i="6600,9927,10914"; a="392688605" X-IronPort-AV: E=Sophos;i="6.04,251,1695711600"; d="scan'208";a="392688605" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Dec 2023 16:45:27 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10914"; a="888704371" X-IronPort-AV: E=Sophos;i="6.04,251,1695711600"; d="scan'208";a="888704371" Received: from abijaz-mobl2.ger.corp.intel.com (HELO box.shutemov.name) ([10.252.61.240]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Dec 2023 16:45:22 -0800 Received: by box.shutemov.name (Postfix, from userid 1000) id 4B55F10A441; Tue, 5 Dec 2023 03:45:20 +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: [PATCHv4 03/14] cpu/hotplug: Add support for declaring CPU offlining not supported Date: Tue, 5 Dec 2023 03:44:59 +0300 Message-ID: <20231205004510.27164-4-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231205004510.27164-1-kirill.shutemov@linux.intel.com> References: <20231205004510.27164-1-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" The ACPI MADT mailbox wakeup method doesn't allow to offline CPU after it got woke up. Currently offlining hotplug is 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. The MADT wakeup can be implemented outside of a confidential computing environment. Offline support is a property of the wakeup method, not the CoCo implementation. Introduce cpu_hotplug_disable_offlining() 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 wakeup method. Signed-off-by: Kirill A. Shutemov Reviewed-by: Thomas Gleixner --- 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 fc8094419084..46f2e34a0c5e 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -134,6 +134,7 @@ 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); @@ -149,6 +150,7 @@ 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 a86972a91991..af8034ccda8e 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 @@ -1522,7 +1532,8 @@ 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