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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 7F6B7CA9EA0 for ; Fri, 25 Oct 2019 14:05:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56C9020679 for ; Fri, 25 Oct 2019 14:05:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572012301; bh=Kng16m/t/WNxtUlNeRND0rxRsZYZ9Z4Lln/p1bnA7HM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=wTt2AnheTLXfGMfXEqiGsp4JeWfEkSVwqtIgHpq+2XBD428YzWAJk5l+WQfoeZne+ cffgkWEZ9vL08Gcl6ngP04NTmpp5yFr4d/fqDgIbFgvqiGDYJgi0YspBHbWZI34zJ8 i3zxs2Kqtll7UGzknVyzqySn80iRUzUCYsFXLKEU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2632844AbfJYN4b (ORCPT ); Fri, 25 Oct 2019 09:56:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:50696 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2393547AbfJYN4W (ORCPT ); Fri, 25 Oct 2019 09:56:22 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 15F24222BD; Fri, 25 Oct 2019 13:56:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572011781; bh=Kng16m/t/WNxtUlNeRND0rxRsZYZ9Z4Lln/p1bnA7HM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ntNtq83ft2ZJ/1APDsZzioMitK0dAQuQUw71kTvH+XYmpQfc3O0A3UjQZusdCP4Vq KTpatm7D1+uyQIHkmheBZ7hOANYi6RUrBlCw/t9E8x9aak360NJUHsVhWfbefdeSvq U/gBpV/GOAdyesUYFNKRjWMuBPdWLzXNFK2P2+wI= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Alexey Kardashevskiy , Paul Mackerras , Sasha Levin , kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 4.19 11/37] KVM: PPC: Book3S HV: Fix lockdep warning when entering the guest Date: Fri, 25 Oct 2019 09:55:35 -0400 Message-Id: <20191025135603.25093-11-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191025135603.25093-1-sashal@kernel.org> References: <20191025135603.25093-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexey Kardashevskiy [ Upstream commit 3309bec85e60d60d6394802cb8e183a4f4a72def ] The trace_hardirqs_on() sets current->hardirqs_enabled and from here the lockdep assumes interrupts are enabled although they are remain disabled until the context switches to the guest. Consequent srcu_read_lock() checks the flags in rcu_lock_acquire(), observes disabled interrupts and prints a warning (see below). This moves trace_hardirqs_on/off closer to __kvmppc_vcore_entry to prevent lockdep from being confused. DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) WARNING: CPU: 16 PID: 8038 at kernel/locking/lockdep.c:4128 check_flags.part.25+0x224/0x280 [...] NIP [c000000000185b84] check_flags.part.25+0x224/0x280 LR [c000000000185b80] check_flags.part.25+0x220/0x280 Call Trace: [c000003fec253710] [c000000000185b80] check_flags.part.25+0x220/0x280 (unreliable) [c000003fec253780] [c000000000187ea4] lock_acquire+0x94/0x260 [c000003fec253840] [c00800001a1e9768] kvmppc_run_core+0xa60/0x1ab0 [kvm_hv] [c000003fec253a10] [c00800001a1ed944] kvmppc_vcpu_run_hv+0x73c/0xec0 [kvm_hv] [c000003fec253ae0] [c00800001a1095dc] kvmppc_vcpu_run+0x34/0x48 [kvm] [c000003fec253b00] [c00800001a1056bc] kvm_arch_vcpu_ioctl_run+0x2f4/0x400 [kvm] [c000003fec253b90] [c00800001a0f3618] kvm_vcpu_ioctl+0x460/0x850 [kvm] [c000003fec253d00] [c00000000041c4f4] do_vfs_ioctl+0xe4/0x930 [c000003fec253db0] [c00000000041ce04] ksys_ioctl+0xc4/0x110 [c000003fec253e00] [c00000000041ce78] sys_ioctl+0x28/0x80 [c000003fec253e20] [c00000000000b5a4] system_call+0x5c/0x70 Instruction dump: 419e0034 3d220004 39291730 81290000 2f890000 409e0020 3c82ffc6 3c62ffc5 3884be70 386329c0 4bf6ea71 60000000 <0fe00000> 3c62ffc6 3863be90 4801273d irq event stamp: 1025 hardirqs last enabled at (1025): [] kvmppc_run_core+0xa20/0x1ab0 [kvm_hv] hardirqs last disabled at (1024): [] kvmppc_run_core+0x650/0x1ab0 [kvm_hv] softirqs last enabled at (0): [] copy_process.isra.4.part.5+0x5f0/0x1d00 softirqs last disabled at (0): [<0000000000000000>] (null) ---[ end trace 31180adcc848993e ]--- possible reason: unannotated irqs-off. irq event stamp: 1025 hardirqs last enabled at (1025): [] kvmppc_run_core+0xa20/0x1ab0 [kvm_hv] hardirqs last disabled at (1024): [] kvmppc_run_core+0x650/0x1ab0 [kvm_hv] softirqs last enabled at (0): [] copy_process.isra.4.part.5+0x5f0/0x1d00 softirqs last disabled at (0): [<0000000000000000>] (null) Fixes: 8b24e69fc47e ("KVM: PPC: Book3S HV: Close race with testing for signals on guest entry", 2017-06-26) Signed-off-by: Alexey Kardashevskiy Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin --- arch/powerpc/kvm/book3s_hv.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 3ae3e8d141e3e..dbfe32327212e 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2993,25 +2993,26 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) } } - /* - * Interrupts will be enabled once we get into the guest, - * so tell lockdep that we're about to enable interrupts. - */ - trace_hardirqs_on(); - guest_enter_irqoff(); srcu_idx = srcu_read_lock(&vc->kvm->srcu); this_cpu_disable_ftrace(); + /* + * Interrupts will be enabled once we get into the guest, + * so tell lockdep that we're about to enable interrupts. + */ + trace_hardirqs_on(); + trap = __kvmppc_vcore_entry(); + trace_hardirqs_off(); + this_cpu_enable_ftrace(); srcu_read_unlock(&vc->kvm->srcu, srcu_idx); - trace_hardirqs_off(); set_irq_happened(trap); spin_lock(&vc->lock); -- 2.20.1