From mboxrd@z Thu Jan 1 00:00:00 1970 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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 AA24DC04AAC for ; Mon, 20 May 2019 10:36:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 871BB206B6 for ; Mon, 20 May 2019 10:36:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731664AbfETKge (ORCPT ); Mon, 20 May 2019 06:36:34 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:35909 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731122AbfETKge (ORCPT ); Mon, 20 May 2019 06:36:34 -0400 Received: by mail-wr1-f66.google.com with SMTP id s17so14013689wru.3 for ; Mon, 20 May 2019 03:36:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Mu2Z3UHH7f9ccDUy0/A9TZhUKTVMZskH29YGAuodbA0=; b=eFtzq0216n0Ho38jZ39XuMNTkU6T3AVN2b+TorgcTJqQzhDg+Ep00t+DAxIsDr/7wQ Pa4qXGz8q92vpcJf0+1Y+iXn3CH6EFTX3cjLWomz3+WlLo6QjXZM/btV8QtHasA7Nx/S C/lylSfJZxtwr8xqG7rPd2eVdOp90MDlePej77QTTIv0cbTvSMoouE/fEckBKsL5C6Ig SGAXofR5Z3AmWpCgLSfytx/71zAQgzU3Xg6GHaUr459r1xbARcbFKeIFoUXFwlWQAqDm wmQzJDmF4+is4sQbruwVpZpnhx1h9R2D+w1PnJw9PxdaXc6A9b/67M0fo485/ERgnM8A 8jlA== X-Gm-Message-State: APjAAAURwr+mAlIFns7mZVfXHSnXG27MG/AFrVv0mN4/CvYqsfa9mLHt C84MzRvMMF5gUGaeAm3DMl5+qA== X-Google-Smtp-Source: APXvYqxVifVEVflPIpthzfCRaNpbf0QfwZg7hpDF9hT0mMHu42X0q0gZvqU16/M7Zkxjk2ApohQ3OA== X-Received: by 2002:adf:e311:: with SMTP id b17mr25372761wrj.11.1558348592580; Mon, 20 May 2019 03:36:32 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:ac04:eef9:b257:b844? ([2001:b07:6468:f312:ac04:eef9:b257:b844]) by smtp.gmail.com with ESMTPSA id y17sm14563641wrp.70.2019.05.20.03.36.31 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 20 May 2019 03:36:32 -0700 (PDT) Subject: Re: [PATCH 3/4] KVM: Fix spinlock taken warning during host resume To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , "Paul E . McKenney" References: <1558082990-7822-1-git-send-email-wanpengli@tencent.com> <1558082990-7822-3-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Message-ID: <7cce6762-006a-a21c-6400-6c0166428cf1@redhat.com> Date: Mon, 20 May 2019 12:36:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <1558082990-7822-3-git-send-email-wanpengli@tencent.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/05/19 10:49, Wanpeng Li wrote: > From: Wanpeng Li > > WARNING: CPU: 0 PID: 13554 at kvm/arch/x86/kvm//../../../virt/kvm/kvm_main.c:4183 kvm_resume+0x3c/0x40 [kvm] > CPU: 0 PID: 13554 Comm: step_after_susp Tainted: G OE 5.1.0-rc4+ #1 > RIP: 0010:kvm_resume+0x3c/0x40 [kvm] > Call Trace: > syscore_resume+0x63/0x2d0 > suspend_devices_and_enter+0x9d1/0xa40 > pm_suspend+0x33a/0x3b0 > state_store+0x82/0xf0 > kobj_attr_store+0x12/0x20 > sysfs_kf_write+0x4b/0x60 > kernfs_fop_write+0x120/0x1a0 > __vfs_write+0x1b/0x40 > vfs_write+0xcd/0x1d0 > ksys_write+0x5f/0xe0 > __x64_sys_write+0x1a/0x20 > do_syscall_64+0x6f/0x6c0 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Commit ca84d1a24 (KVM: x86: Add clock sync request to hardware enable) mentioned > that "we always hold kvm_lock when hardware_enable is called. The one place that > doesn't need to worry about it is resume, as resuming a frozen CPU, the spinlock > won't be taken." However, commit 6706dae9 (virt/kvm: Replace spin_is_locked() with > lockdep) introduces a bug, it asserts when the lock is not held which is contrary > to the original goal. > > This patch fixes it by WARN_ON when the lock is held. > > Cc: Paolo Bonzini > Cc: Radim Krčmář > Cc: Paul E. McKenney > Signed-off-by: Wanpeng Li > --- > virt/kvm/kvm_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 5fb0f16..c7eab5f 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -4096,7 +4096,7 @@ static int kvm_suspend(void) > static void kvm_resume(void) > { > if (kvm_usage_count) { > - lockdep_assert_held(&kvm_count_lock); > + WARN_ON(lockdep_is_held(&kvm_count_lock)); > hardware_enable_nolock(NULL); > } > } > Queued, thanks. Paolo