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=-15.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 F2FEBC433DB for ; Wed, 17 Feb 2021 09:19:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B935264E33 for ; Wed, 17 Feb 2021 09:19:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232113AbhBQJTU (ORCPT ); Wed, 17 Feb 2021 04:19:20 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:21284 "EHLO mx0b-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229553AbhBQJTL (ORCPT ); Wed, 17 Feb 2021 04:19:11 -0500 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 11H90dMt026168; Wed, 17 Feb 2021 04:18:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=Ia97Hv6vISsG9Ib9rQmb1DZFC45uId5MKmhx6AfP8W8=; b=YxKvHF0avTHXHFMcyQSst74SbNLMamyS0ABtA65fa/D0yFOUgmdvZeZfNrxUikxrM5n/ xN1vLljgqPjSTP4Thf7Wh2WFh3kyRYlQhn+Y/Q9Kjsba7LFh4BINixli1pKHzev0ELTy G4R2rMBVZlP8Co7LYN7Vi9hkfhQ7i6ArSVKc/9kxzt6qoKz+mKY0hl/XYZPDkaTBHkSm iz1kfviRZeDMCrfnao5TvYX6fdEruZyGil6fXM+j5ickk11JF+E5ArfpVdsStrDbid0n XSXtHmV3AhftCPiaTxVVupJtiD8mDPjtYUJD83rT5RwsNM7wY4wRjPtRJjqkJ1ug5RPS UA== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 36s03brqb3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 17 Feb 2021 04:18:21 -0500 Received: from m0098421.ppops.net (m0098421.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 11H9HjAQ103877; Wed, 17 Feb 2021 04:18:21 -0500 Received: from ppma04ams.nl.ibm.com (63.31.33a9.ip4.static.sl-reverse.com [169.51.49.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 36s03brqaf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 17 Feb 2021 04:18:21 -0500 Received: from pps.filterd (ppma04ams.nl.ibm.com [127.0.0.1]) by ppma04ams.nl.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 11H9DhxN010720; Wed, 17 Feb 2021 09:18:18 GMT Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by ppma04ams.nl.ibm.com with ESMTP id 36p6d8bhq5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 17 Feb 2021 09:18:18 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 11H9IGvZ36897094 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Feb 2021 09:18:16 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6CD59A405E; Wed, 17 Feb 2021 09:18:16 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B8429A4053; Wed, 17 Feb 2021 09:18:12 +0000 (GMT) Received: from [9.160.89.213] (unknown [9.160.89.213]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 17 Feb 2021 09:18:12 +0000 (GMT) Subject: Re: [PATCH for 5.4] Fix unsynchronized access to sev members through svm_register_enc_region To: Peter Gonda , stable@vger.kernel.org Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Paolo Bonzini , Joerg Roedel , Tom Lendacky , Brijesh Singh , Sean Christopherson , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210208164855.772287-1-pgonda@google.com> From: Dov Murik Message-ID: <2ddf06e9-a541-3d9c-3a0c-db557a04afcc@linux.vnet.ibm.com> Date: Wed, 17 Feb 2021 11:18:11 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210208164855.772287-1-pgonda@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-17_06:2021-02-16,2021-02-17 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 malwarescore=0 bulkscore=0 mlxlogscore=999 phishscore=0 adultscore=0 impostorscore=0 spamscore=0 suspectscore=0 mlxscore=0 priorityscore=1501 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102170064 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, On 08/02/2021 18:48, Peter Gonda wrote: > commit 19a23da53932bc8011220bd8c410cb76012de004 upstream. > > Grab kvm->lock before pinning memory when registering an encrypted > region; sev_pin_memory() relies on kvm->lock being held to ensure > correctness when checking and updating the number of pinned pages. > > Add a lockdep assertion to help prevent future regressions. > > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Cc: Paolo Bonzini > Cc: Joerg Roedel > Cc: Tom Lendacky > Cc: Brijesh Singh > Cc: Sean Christopherson > Cc: x86@kernel.org > Cc: kvm@vger.kernel.org > Cc: stable@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Fixes: 1e80fdc09d12 ("KVM: SVM: Pin guest memory when SEV is active") > Signed-off-by: Peter Gonda > > V2 > - Fix up patch description > - Correct file paths svm.c -> sev.c > - Add unlock of kvm->lock on sev_pin_memory error > > V1 > - https://lore.kernel.org/kvm/20210126185431.1824530-1-pgonda@google.com/ > > Message-Id: <20210127161524.2832400-1-pgonda@google.com> > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/svm.c | 18 +++++++++++------- > 1 file changed, 11 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 2b506904be02..93c89f1ffc5d 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -1830,6 +1830,8 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr, > struct page **pages; > unsigned long first, last; > > + lockdep_assert_held(&kvm->lock); > + > if (ulen == 0 || uaddr + ulen < uaddr) > return NULL; > > @@ -7086,12 +7088,21 @@ static int svm_register_enc_region(struct kvm *kvm, > if (!region) > return -ENOMEM; > > + mutex_lock(&kvm->lock); > region->pages = sev_pin_memory(kvm, range->addr, range->size, ®ion->npages, 1); > if (!region->pages) { > ret = -ENOMEM; > + mutex_unlock(&kvm->lock); > goto e_free; > } > > + region->uaddr = range->addr; > + region->size = range->size; > + > + mutex_lock(&kvm->lock); This extra mutex_lock call doesn't appear in the upstream patch (committed as 19a23da5393), but does appear in the 5.4 and 4.19 backports. Is it needed here? -Dov > + list_add_tail(®ion->list, &sev->regions_list); > + mutex_unlock(&kvm->lock); > + > /* > * The guest may change the memory encryption attribute from C=0 -> C=1 > * or vice versa for this memory range. Lets make sure caches are > @@ -7100,13 +7111,6 @@ static int svm_register_enc_region(struct kvm *kvm, > */ > sev_clflush_pages(region->pages, region->npages); > > - region->uaddr = range->addr; > - region->size = range->size; > - > - mutex_lock(&kvm->lock); > - list_add_tail(®ion->list, &sev->regions_list); > - mutex_unlock(&kvm->lock); > - > return ret; > > e_free: >