From patchwork Wed Dec 18 16:01:30 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 3370701 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 6B18AC0D4A for ; Wed, 18 Dec 2013 16:02:26 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 541EB2013A for ; Wed, 18 Dec 2013 16:02:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 990C0201BE for ; Wed, 18 Dec 2013 16:02:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754971Ab3LRQBn (ORCPT ); Wed, 18 Dec 2013 11:01:43 -0500 Received: from cantor2.suse.de ([195.135.220.15]:58031 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754933Ab3LRQBl (ORCPT ); Wed, 18 Dec 2013 11:01:41 -0500 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id E49DEAC3A; Wed, 18 Dec 2013 16:01:40 +0000 (UTC) From: Alexander Graf To: kvm-ppc@vger.kernel.org Cc: "kvm@vger.kernel.org mailing list" , Paolo Bonzini , Gleb Natapov , Paul Mackerras Subject: [PULL 04/12] KVM: PPC: Book3S HV: Take SRCU read lock around kvm_read_guest() call Date: Wed, 18 Dec 2013 17:01:30 +0100 Message-Id: <1387382498-19817-5-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1387382498-19817-1-git-send-email-agraf@suse.de> References: <1387382498-19817-1-git-send-email-agraf@suse.de> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-7.4 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Paul Mackerras Running a kernel with CONFIG_PROVE_RCU=y yields the following diagnostic: =============================== [ INFO: suspicious RCU usage. ] 3.12.0-rc5-kvm+ #9 Not tainted ------------------------------- include/linux/kvm_host.h:473 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 1 lock held by qemu-system-ppc/4831: stack backtrace: CPU: 28 PID: 4831 Comm: qemu-system-ppc Not tainted 3.12.0-rc5-kvm+ #9 Call Trace: [c000000be462b2a0] [c00000000001644c] .show_stack+0x7c/0x1f0 (unreliable) [c000000be462b370] [c000000000ad57c0] .dump_stack+0x88/0xb4 [c000000be462b3f0] [c0000000001315e8] .lockdep_rcu_suspicious+0x138/0x180 [c000000be462b480] [c00000000007862c] .gfn_to_memslot+0x13c/0x170 [c000000be462b510] [c00000000007d384] .gfn_to_hva_prot+0x24/0x90 [c000000be462b5a0] [c00000000007d420] .kvm_read_guest_page+0x30/0xd0 [c000000be462b630] [c00000000007d528] .kvm_read_guest+0x68/0x110 [c000000be462b6e0] [c000000000084594] .kvmppc_rtas_hcall+0x34/0x180 [c000000be462b7d0] [c000000000097934] .kvmppc_pseries_do_hcall+0x74/0x830 [c000000be462b880] [c0000000000990e8] .kvmppc_vcpu_run_hv+0xff8/0x15a0 [c000000be462b9e0] [c0000000000839cc] .kvmppc_vcpu_run+0x2c/0x40 [c000000be462ba50] [c0000000000810b4] .kvm_arch_vcpu_ioctl_run+0x54/0x1b0 [c000000be462bae0] [c00000000007b508] .kvm_vcpu_ioctl+0x478/0x730 [c000000be462bca0] [c00000000025532c] .do_vfs_ioctl+0x4dc/0x7a0 [c000000be462bd80] [c0000000002556b4] .SyS_ioctl+0xc4/0xe0 [c000000be462be30] [c000000000009ee4] syscall_exit+0x0/0x98 To fix this, we take the SRCU read lock around the kvmppc_rtas_hcall() call. Signed-off-by: Paul Mackerras Signed-off-by: Alexander Graf --- arch/powerpc/kvm/book3s_hv.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 31d9cfb..b51d5db 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -591,7 +591,9 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) if (list_empty(&vcpu->kvm->arch.rtas_tokens)) return RESUME_HOST; + idx = srcu_read_lock(&vcpu->kvm->srcu); rc = kvmppc_rtas_hcall(vcpu); + srcu_read_unlock(&vcpu->kvm->srcu, idx); if (rc == -ENOENT) return RESUME_HOST;