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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0D75C7EE23 for ; Tue, 23 May 2023 14:05:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236786AbjEWOFK (ORCPT ); Tue, 23 May 2023 10:05:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231136AbjEWOFK (ORCPT ); Tue, 23 May 2023 10:05:10 -0400 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 750E1FA; Tue, 23 May 2023 07:05:08 -0700 (PDT) Received: from pps.filterd (m0353723.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 34NDlU6u021219; Tue, 23 May 2023 14:05:07 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=pp1; bh=NtR5MxzMGSuK7kXRmXQD+66JEk0RpgyLWCD7TwINmBY=; b=q0y0ZeOnktXhZfWaXa9JstB2brsb5xccgISQcUz2bBpvN8Tqn6/j0OktXY4QuOhDzkpO LFc80HmQ69KW9zye2tRv6q74p4pCx+9FlKn2cT90l7w5mUAvmGs2Z2PGDJw8kPLtIytg EYRMlOyEGBmZa77Eqw1SyoVonq/Vk1kvhoqUJbMcwT4HeHdZAOXjyoU6105hNK5plZpX YGoA3F+H6V4SIfE9PgxUCoy65fFPWfAxL7bfsvnd02eHoXQS8yxv7ExSGzyf/9yYzbjS +PgortHWsuNP4YD81Bl9UZg1kK39xc2DUrOu97yuc9/LDIjBCUMJKFllK45MXhJ66Td7 bw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3qrweutq83-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 23 May 2023 14:05:07 +0000 Received: from m0353723.ppops.net (m0353723.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 34NDrFRl022338; Tue, 23 May 2023 14:05:07 GMT Received: from ppma05fra.de.ibm.com (6c.4a.5195.ip4.static.sl-reverse.com [149.81.74.108]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3qrweutq71-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 23 May 2023 14:05:06 +0000 Received: from pps.filterd (ppma05fra.de.ibm.com [127.0.0.1]) by ppma05fra.de.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 34N5RC24032122; Tue, 23 May 2023 14:05:05 GMT Received: from smtprelay03.fra02v.mail.ibm.com ([9.218.2.224]) by ppma05fra.de.ibm.com (PPS) with ESMTPS id 3qppbmh8fa-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 23 May 2023 14:05:05 +0000 Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay03.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 34NE51cR18547216 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 23 May 2023 14:05:01 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8DE2A2004F; Tue, 23 May 2023 14:05:01 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7C9D02004D; Tue, 23 May 2023 14:05:01 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTPS; Tue, 23 May 2023 14:05:01 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 25651) id 2311DE04A4; Tue, 23 May 2023 16:05:01 +0200 (CEST) From: Christian Borntraeger To: KVM Cc: Christian Borntraeger , Janosch Frank , David Hildenbrand , linux-s390 , Thomas Huth , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev Subject: [PATCH] KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler Date: Tue, 23 May 2023 16:05:00 +0200 Message-Id: <20230523140500.271990-1-borntraeger@linux.ibm.com> X-Mailer: git-send-email 2.40.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 2hrvYSpY_etdZyjl0Vgargvl91RrDmVm X-Proofpoint-GUID: 3LXnXwc2tQk-W2x_OhTRqJ56tCMHuWlU X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.573,FMLib:17.11.176.26 definitions=2023-05-23_09,2023-05-23_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 spamscore=0 adultscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 suspectscore=0 mlxlogscore=999 mlxscore=0 clxscore=1011 malwarescore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2304280000 definitions=main-2305230106 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org We do check for target CPU == -1, but this might change at the time we are going to use it. Hold the physical target CPU in a local variable to avoid out-of-bound accesses to the cpu arrays. Cc: Pierre Morel Fixes: 87e28a15c42c ("KVM: s390: diag9c (directed yield) forwarding") Reported-by: Marc Hartmayer Reviewed-by: Nico Boehr Reviewed-by: Pierre Morel Signed-off-by: Christian Borntraeger --- arch/s390/kvm/diag.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c index 807fa9da1e72..3c65b8258ae6 100644 --- a/arch/s390/kvm/diag.c +++ b/arch/s390/kvm/diag.c @@ -166,6 +166,7 @@ static int diag9c_forwarding_overrun(void) static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu) { struct kvm_vcpu *tcpu; + int tcpu_cpu; int tid; tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4]; @@ -181,14 +182,15 @@ static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu) goto no_yield; /* target guest VCPU already running */ - if (READ_ONCE(tcpu->cpu) >= 0) { + tcpu_cpu = READ_ONCE(tcpu->cpu); + if (tcpu_cpu >= 0) { if (!diag9c_forwarding_hz || diag9c_forwarding_overrun()) goto no_yield; /* target host CPU already running */ - if (!vcpu_is_preempted(tcpu->cpu)) + if (!vcpu_is_preempted(tcpu_cpu)) goto no_yield; - smp_yield_cpu(tcpu->cpu); + smp_yield_cpu(tcpu_cpu); VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: yield forwarded", tid); -- 2.40.1