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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 1B22BC33CA1 for ; Wed, 5 Feb 2020 09:03:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7C2220659 for ; Wed, 5 Feb 2020 09:03:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728112AbgBEJDK (ORCPT ); Wed, 5 Feb 2020 04:03:10 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:10104 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727068AbgBEJDK (ORCPT ); Wed, 5 Feb 2020 04:03:10 -0500 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0158wvvF138631 for ; Wed, 5 Feb 2020 04:03:09 -0500 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2xyhn3xyjr-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 05 Feb 2020 04:03:09 -0500 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 5 Feb 2020 09:03:04 -0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 0159322E45351320 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 5 Feb 2020 09:03:02 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 589E94C062; Wed, 5 Feb 2020 09:03:02 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 134F64C050; Wed, 5 Feb 2020 09:03:02 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.61]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 5 Feb 2020 09:03:02 +0000 (GMT) Subject: Re: [RFCv2 11/37] KVM: s390/mm: Make pages accessible before destroying the guest To: Thomas Huth , Janosch Frank Cc: KVM , Cornelia Huck , David Hildenbrand , Ulrich Weigand , Claudio Imbrenda , Andrea Arcangeli References: <20200203131957.383915-1-borntraeger@de.ibm.com> <20200203131957.383915-12-borntraeger@de.ibm.com> <7b73da46-ad64-3ab5-cd59-5a302bbbdc5f@redhat.com> From: Christian Borntraeger Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <7b73da46-ad64-3ab5-cd59-5a302bbbdc5f@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 20020509-0020-0000-0000-000003A7243A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20020509-0021-0000-0000-000021FEEDBF Message-Id: <6b3d7f0a-8cf8-8b2a-370a-ddbc6628941c@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-02-05_02:2020-02-04,2020-02-05 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 phishscore=0 mlxlogscore=796 impostorscore=0 mlxscore=0 suspectscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002050072 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 04.02.20 21:52, Thomas Huth wrote: > On 03/02/2020 14.19, Christian Borntraeger wrote: >> Before we destroy the secure configuration, we better make all >> pages accessible again. This also happens during reboot, where we reboot >> into a non-secure guest that then can go again into a secure mode. As >> this "new" secure guest will have a new ID we cannot reuse the old page >> state. >> >> Signed-off-by: Christian Borntraeger >> --- >> arch/s390/include/asm/pgtable.h | 1 + >> arch/s390/kvm/pv.c | 2 ++ >> arch/s390/mm/gmap.c | 35 +++++++++++++++++++++++++++++++++ >> 3 files changed, 38 insertions(+) >> >> diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h >> index 65b6bb47af0a..6e167dcc35f1 100644 >> --- a/arch/s390/include/asm/pgtable.h >> +++ b/arch/s390/include/asm/pgtable.h >> @@ -1669,6 +1669,7 @@ extern int vmem_remove_mapping(unsigned long start, unsigned long size); >> extern int s390_enable_sie(void); >> extern int s390_enable_skey(void); >> extern void s390_reset_cmma(struct mm_struct *mm); >> +extern void s390_reset_acc(struct mm_struct *mm); >> >> /* s390 has a private copy of get unmapped area to deal with cache synonyms */ >> #define HAVE_ARCH_UNMAPPED_AREA >> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c >> index a867b9e9c069..24d802072ac7 100644 >> --- a/arch/s390/kvm/pv.c >> +++ b/arch/s390/kvm/pv.c >> @@ -66,6 +66,8 @@ int kvm_s390_pv_destroy_vm(struct kvm *kvm) >> int rc; >> u32 ret; >> >> + /* make all pages accessible before destroying the guest */ >> + s390_reset_acc(kvm->mm); >> rc = uv_cmd_nodata(kvm_s390_pv_handle(kvm), >> UVC_CMD_DESTROY_SEC_CONF, &ret); >> WRITE_ONCE(kvm->arch.gmap->se_handle, 0); >> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c >> index bf365a09f900..0b00e8d5fa39 100644 >> --- a/arch/s390/mm/gmap.c >> +++ b/arch/s390/mm/gmap.c >> @@ -2648,3 +2648,38 @@ void s390_reset_cmma(struct mm_struct *mm) >> up_write(&mm->mmap_sem); >> } >> EXPORT_SYMBOL_GPL(s390_reset_cmma); >> + >> +/* >> + * make inaccessible pages accessible again >> + */ >> +static int __s390_reset_acc(pte_t *ptep, unsigned long addr, >> + unsigned long next, struct mm_walk *walk) >> +{ >> + pte_t pte = READ_ONCE(*ptep); >> + >> + if (pte_present(pte)) >> + uv_convert_from_secure(pte_val(pte) & PAGE_MASK); > > Is it ok to ignore the return value from uv_convert_from_secure() ? > Problems might go unnoticed ... maybe use at least a WARN_ONCE ? Hmm, it is certainly one of these "should not happen" cases. So yes, I will add a WARN_ON_ONCE. > >> + return 0; >> +} >> + >> +static const struct mm_walk_ops reset_acc_walk_ops = { >> + .pte_entry = __s390_reset_acc, >> +}; >> + >> +#include >> +void s390_reset_acc(struct mm_struct *mm) >> +{ >> + /* >> + * we might be called during >> + * reset: we walk the pages and clear >> + * close of all kvm file descriptor: we walk the pages and clear >> + * exit of process on fd closure: vma already gone, do nothing >> + */ >> + if (!mmget_not_zero(mm)) >> + return; >> + down_read(&mm->mmap_sem); >> + walk_page_range(mm, 0, TASK_SIZE, &reset_acc_walk_ops, NULL); >> + up_read(&mm->mmap_sem); >> + mmput(mm); >> +} >> +EXPORT_SYMBOL_GPL(s390_reset_acc); >> > > Anyway, > Reviewed-by: Thomas Huth > thanks.