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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 2F04CC34047 for ; Wed, 19 Feb 2020 17:30:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 057F220801 for ; Wed, 19 Feb 2020 17:30:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726651AbgBSRae (ORCPT ); Wed, 19 Feb 2020 12:30:34 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:38933 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726518AbgBSRae (ORCPT ); Wed, 19 Feb 2020 12:30:34 -0500 Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1j4TB4-0000t5-Lz; Wed, 19 Feb 2020 18:30:26 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 28025103A01; Wed, 19 Feb 2020 18:30:26 +0100 (CET) From: Thomas Gleixner To: =?utf-8?B?SsO8cmdlbiBHcm/Dnw==?= , LKML Cc: x86@kernel.org, Boris Ostrovsky , Stefano Stabellini , xen-devel@lists.xenproject.org Subject: [PATCH V2] xen: Enable interrupts when calling _cond_resched() In-Reply-To: <87h7zmpr1k.fsf@nanos.tec.linutronix.de> References: <87tv3mq1rm.fsf@nanos.tec.linutronix.de> <8808612b-11c2-f7b8-f027-7ff92e992c50@suse.com> <87h7zmpr1k.fsf@nanos.tec.linutronix.de> Date: Wed, 19 Feb 2020 18:30:26 +0100 Message-ID: <878skypjrh.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org xen_maybe_preempt_hcall() is called from the exception entry point xen_do_hypervisor_callback with interrupts disabled. _cond_resched() evades the might_sleep() check in cond_resched() which would have caught that and schedule_debug() unfortunately lacks a check for irqs_disabled(). Enable interrupts around the call and use cond_resched() to catch future issues. Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted") Signed-off-by: Thomas Gleixner --- V2: Put local_irq_disable() where it belongs. --- drivers/xen/preempt.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/xen/preempt.c +++ b/drivers/xen/preempt.c @@ -33,7 +33,9 @@ asmlinkage __visible void xen_maybe_pree * cpu. */ __this_cpu_write(xen_in_preemptible_hcall, false); - _cond_resched(); + local_irq_enable(); + cond_resched(); + local_irq_disable(); __this_cpu_write(xen_in_preemptible_hcall, true); } }