From patchwork Tue Mar 28 19:57:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13191501 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 6DC85C6FD18 for ; Tue, 28 Mar 2023 19:58:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229865AbjC1T6x (ORCPT ); Tue, 28 Mar 2023 15:58:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42656 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229744AbjC1T6i (ORCPT ); Tue, 28 Mar 2023 15:58:38 -0400 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E7F2B3C3A for ; Tue, 28 Mar 2023 12:58:03 -0700 (PDT) Received: by mail-wr1-x433.google.com with SMTP id i9so13419426wrp.3 for ; Tue, 28 Mar 2023 12:58:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1680033482; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=XHD5cN+9NG2teoVVuOSus5vfOKvUrEkkcqEu7E43kuM=; b=ZWbGy/qB9O4uIXmbnFJPzgndZVBdjQ7fRWg0uO8JRvcFhlus0uhdFK85yQMon2+hSO Ih2Wuad+2T/mmT1ReIQ8AzXzEN4Hxo/5h5gvFLl/p9mYvN1NUYN/NNqXtZlRqcLhiAGd bK4JNMc7njvwdLhuMUDHpOQImnYK+97PG5LALvKK5WqgXgLC4EzHEGyk3E8j07YoebtM 8N/QPVWvNnKs5om6hiI2QilQDcUi29GH4R+a6NFfomkEIZ8PeFU3l5xDhAtNZYFRoo2K fWKRYD4KdIaWpHtqTqbLn214mh6hCmJG67hDxryH+ErkUnM+o5jnnRs7F6+DfSLVp/t8 rY7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680033482; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=XHD5cN+9NG2teoVVuOSus5vfOKvUrEkkcqEu7E43kuM=; b=Y6unlbs2HyURCiwpdpqbEdbsqJGTzbsvel9QclQY5pSrlP2BLWHoncxbsQoZfaMniJ 6zz8EviRhRlrmmhFBkoLug9gB+Yx/Hz/al/fd9p3nUCU7b94tU0MoBgE/sHIC5DSsOH1 P0/cjwurLB6VM1iSAd3T3GCqu6jT29S+m7e6Ml09B8ZHC5CfUmQrmayvdZadDNQiL6pk plaFGLk5PX7rJzZozHj7DmFX1m3+i30S38hJJay3MctEaO5MlCm66P0+PM+k4zuk2yF5 9oZFkrFkxm5sWLfJtAzHKdCc7xtoPDSNnlLgjFkJAiqDacrTvIeu5M5oXbeDAXrVHJAw Z/vg== X-Gm-Message-State: AAQBX9cD5GcrLcmHYpi0PRlIqDDdY96UTZXi1qt63H6JZJjzg3tH5oqy +y++cJsnb7bXoW+BR2p5XGW8hA== X-Google-Smtp-Source: AKy350a+CkM599ZmoWKEKahYxx4p6YM4cZDHr6OxnnBGr3OOYOjDokmLrgjI/ZkKjBeWoPEYwQ+P+w== X-Received: by 2002:a05:6000:542:b0:2d1:7ade:aad with SMTP id b2-20020a056000054200b002d17ade0aadmr13593380wrf.31.1680033482442; Tue, 28 Mar 2023 12:58:02 -0700 (PDT) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6a:b566:0:8445:3123:91d7:959d]) by smtp.gmail.com with ESMTPSA id z6-20020a056000110600b002c557f82e27sm28248386wrw.99.2023.03.28.12.58.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Mar 2023 12:58:02 -0700 (PDT) From: Usama Arif To: dwmw2@infradead.org, tglx@linutronix.de, kim.phillips@amd.com, brgerst@gmail.com Cc: piotrgorski@cachyos.org, oleksandr@natalenko.name, arjan@linux.intel.com, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com, paulmck@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com, pmenzel@molgen.mpg.de, fam.zheng@bytedance.com, punit.agrawal@bytedance.com, simon.evans@bytedance.com, liangma@liangbit.com, gpiccoli@igalia.com, David Woodhouse , Mark Rutland Subject: [PATCH v17 2/8] cpu/hotplug: Reset task stack state in _cpu_up() Date: Tue, 28 Mar 2023 20:57:52 +0100 Message-Id: <20230328195758.1049469-3-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230328195758.1049469-1-usama.arif@bytedance.com> References: <20230328195758.1049469-1-usama.arif@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: David Woodhouse Commit dce1ca0525bf ("sched/scs: Reset task stack state in bringup_cpu()") ensured that the shadow call stack was reset and KASAN poisoning removed from a CPU's stack each time that CPU is brought up, not just once. This is not incorrect. However, with parallel bringup, an architecture may obtain the idle thread for a new CPU from a pre-bringup stage, by calling idle_thread_get() for itself. This would mean that the cleanup in bringup_cpu() would be too late. Move the SCS/KASAN cleanup to the generic _cpu_up() function instead, which already ensures that the new CPU's stack is available, purely to allow for early failure. This occurs when the CPU to be brought up is in the CPUHP_OFFLINE state, which should correctly do the cleanup any time the CPU has been taken down to the point where such is needed. Signed-off-by: David Woodhouse Reviewed-by: Mark Rutland Tested-by: Mark Rutland [arm64] Signed-off-by: Usama Arif --- kernel/cpu.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 6c0a92ca6bb5..43e0a77f21e8 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -591,12 +591,6 @@ static int bringup_cpu(unsigned int cpu) struct task_struct *idle = idle_thread_get(cpu); int ret; - /* - * Reset stale stack state from the last time this CPU was online. - */ - scs_task_reset(idle); - kasan_unpoison_task_stack(idle); - /* * Some architectures have to walk the irq descriptors to * setup the vector space for the cpu which comes online. @@ -1383,6 +1377,12 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) ret = PTR_ERR(idle); goto out; } + + /* + * Reset stale stack state from the last time this CPU was online. + */ + scs_task_reset(idle); + kasan_unpoison_task_stack(idle); } cpuhp_tasks_frozen = tasks_frozen;