From patchwork Mon Jul 24 08:18:04 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Wanpeng Li X-Patchwork-Id: 9858979 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 3574E60385 for ; Mon, 24 Jul 2017 08:18:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 254A9283C7 for ; Mon, 24 Jul 2017 08:18:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 18C1328574; Mon, 24 Jul 2017 08:18:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A39F3283C7 for ; Mon, 24 Jul 2017 08:18:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752830AbdGXISL (ORCPT ); Mon, 24 Jul 2017 04:18:11 -0400 Received: from mail-pg0-f67.google.com ([74.125.83.67]:34678 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750975AbdGXISJ (ORCPT ); Mon, 24 Jul 2017 04:18:09 -0400 Received: by mail-pg0-f67.google.com with SMTP id v190so11107603pgv.1; Mon, 24 Jul 2017 01:18:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=46VWuC7Av3cbFRdx4hpvVL+HytGKWefXa1+7mJ9RpXU=; b=uzf1TB3o5D0vupENl7k+vdV4CsMvZYnx22q9ox8tO7zP09nDshjJaIZ9zALzSKN+us o0HQ60mhfv9IuXeM2mwul2eU0su4zNrCZVnEp2TU9lG8ZZbMLHd0xG9uu4ur6R8jy02t aJtsZvVJWFxOC/GhidK6HeSsOND1dd+QGezmdT0BVZPCoOpr5uWwADvfE5T/09p5IkF1 sIt7CPTI561/WA1y7JexTxrjUkhMh3ttb3TImiEJ5HBvVanW/IYZnnMtP0xsJO/EiqfX CCP5vAnHf63Pa37fyos73xvL2/Z3JfjV2SAOOvzjizVZ+jZk2h7gs8MiWCPO3I5bhDoQ HXGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=46VWuC7Av3cbFRdx4hpvVL+HytGKWefXa1+7mJ9RpXU=; b=IP8vwD1V5evLWgdLtEEHii6peNtOsqCT9TjgDqm7It292waHKHT7EauFQM/FmXfMf0 xcLGq89hEDKJyUnLzWH+9l48zrZh8mvMi1+WwcbMgRK4c9QARBQp23FFwVdwRdqN84L2 mcRjTuH68NIhlgu33C6v5qaLTop9y3eVwlj3a/I3XM4+IPuRkBWYWX5dBR04O3IAkcJV Q+PojvbW5d4sqfbs1ZnHJhpn3K2HfUTjPRLiMAW2RdHntB56V+oJYDhvNW9Cg+Va2Xu8 YCKstLN16/EzCcEX++2pJfF7F3z12y+p0cbhQ4qqdefxJa7T+hkyMQbqyC+EOL93sLOU Z63Q== X-Gm-Message-State: AIVw110TNN6fRaOh3Ef4yWG+yzAzBhCWtsDemULge+M2d8lRROO2h2ez TUbOy9rBW7To/RXE X-Received: by 10.99.227.81 with SMTP id o17mr15211752pgj.41.1500884288742; Mon, 24 Jul 2017 01:18:08 -0700 (PDT) Received: from localhost ([203.205.141.123]) by smtp.gmail.com with ESMTPSA id m18sm19771602pfe.126.2017.07.24.01.18.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Jul 2017 01:18:08 -0700 (PDT) From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Wanpeng Li Subject: [PATCH] KVM: LAPIC: Fix cancel preemption timer repeatedly due to preemption Date: Mon, 24 Jul 2017 01:18:04 -0700 Message-Id: <1500884284-4830-1-git-send-email-wanpeng.li@hotmail.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Wanpeng Li Preemption can occur in the preemption timer expiration handler: CPU0 CPU1 preemption timer vmexit handle_preemption_timer(vCPU0) kvm_lapic_expired_hv_timer hv_timer_is_use == true sched_out sched_in kvm_arch_vcpu_load kvm_lapic_restart_hv_timer restart_apic_timer start_hv_timer already-expired timer or sw timer triggerd in the window start_sw_timer cancel_hv_timer /* back in kvm_lapic_expired_hv_timer */ cancel_hv_timer WARN_ON(!apic->lapic_timer.hv_timer_in_use); ==> Oops This can be reproduced if CONFIG_PREEMPT is enabled. ------------[ cut here ]------------ WARNING: CPU: 4 PID: 2972 at /home/kernel/linux/arch/x86/kvm//lapic.c:1563 kvm_lapic_expired_hv_timer+0x9e/0xb0 [kvm] CPU: 4 PID: 2972 Comm: qemu-system-x86 Tainted: G OE 4.13.0-rc2+ #16 RIP: 0010:kvm_lapic_expired_hv_timer+0x9e/0xb0 [kvm] Call Trace: handle_preemption_timer+0xe/0x20 [kvm_intel] vmx_handle_exit+0xb8/0xd70 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xdd1/0x1be0 [kvm] ? kvm_arch_vcpu_load+0x47/0x230 [kvm] ? kvm_arch_vcpu_load+0x62/0x230 [kvm] kvm_vcpu_ioctl+0x340/0x700 [kvm] ? kvm_vcpu_ioctl+0x340/0x700 [kvm] ? __fget+0xfc/0x210 do_vfs_ioctl+0xa4/0x6a0 ? __fget+0x11d/0x210 SyS_ioctl+0x79/0x90 do_syscall_64+0x81/0x220 entry_SYSCALL64_slow_path+0x25/0x25 ------------[ cut here ]------------ WARNING: CPU: 4 PID: 2972 at /home/kernel/linux/arch/x86/kvm//lapic.c:1498 cancel_hv_timer.isra.40+0x4f/0x60 [kvm] CPU: 4 PID: 2972 Comm: qemu-system-x86 Tainted: G W OE 4.13.0-rc2+ #16 RIP: 0010:cancel_hv_timer.isra.40+0x4f/0x60 [kvm] Call Trace: kvm_lapic_expired_hv_timer+0x3e/0xb0 [kvm] handle_preemption_timer+0xe/0x20 [kvm_intel] vmx_handle_exit+0xb8/0xd70 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xdd1/0x1be0 [kvm] ? kvm_arch_vcpu_load+0x47/0x230 [kvm] ? kvm_arch_vcpu_load+0x62/0x230 [kvm] kvm_vcpu_ioctl+0x340/0x700 [kvm] ? kvm_vcpu_ioctl+0x340/0x700 [kvm] ? __fget+0xfc/0x210 do_vfs_ioctl+0xa4/0x6a0 ? __fget+0x11d/0x210 SyS_ioctl+0x79/0x90 do_syscall_64+0x81/0x220 entry_SYSCALL64_slow_path+0x25/0x25 This patch fixes it by don't cancel preemption timer repeatedly if the preemption timer has already been cancelled due to preemption since already-expired timer or sw timer triggered in the window. Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li --- arch/x86/kvm/lapic.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 2819d4c..8341b40 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1560,9 +1560,13 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; - WARN_ON(!apic->lapic_timer.hv_timer_in_use); - WARN_ON(swait_active(&vcpu->wq)); - cancel_hv_timer(apic); + preempt_disable(); + if (!(!apic_lvtt_period(apic) && atomic_read(&apic->lapic_timer.pending))) { + WARN_ON(!apic->lapic_timer.hv_timer_in_use); + WARN_ON(swait_active(&vcpu->wq)); + cancel_hv_timer(apic); + } + preempt_enable(); apic_timer_expired(apic); if (apic_lvtt_period(apic) && apic->lapic_timer.period) {