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=-8.2 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 E743BC432C0 for ; Thu, 28 Nov 2019 05:04:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A5DC8215F1 for ; Thu, 28 Nov 2019 05:04:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A5DC8215F1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 567316B04FF; Thu, 28 Nov 2019 00:04:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 518A76B0500; Thu, 28 Nov 2019 00:04:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4056F6B0501; Thu, 28 Nov 2019 00:04:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0022.hostedemail.com [216.40.44.22]) by kanga.kvack.org (Postfix) with ESMTP id 2504D6B04FF for ; Thu, 28 Nov 2019 00:04:24 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id C4705181AEF1F for ; Thu, 28 Nov 2019 05:04:23 +0000 (UTC) X-FDA: 76204495206.02.space03_4369e17e2514e X-HE-Tag: space03_4369e17e2514e X-Filterd-Recvd-Size: 7354 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by imf13.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Nov 2019 05:04:23 +0000 (UTC) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xAS513YI113010 for ; Thu, 28 Nov 2019 00:04:22 -0500 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 2whcxrd1xj-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 28 Nov 2019 00:04:21 -0500 Received: from localhost by e06smtp07.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) Thu, 28 Nov 2019 05:04:17 -0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xAS53agB30736702 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Nov 2019 05:03:36 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 579EBA4062; Thu, 28 Nov 2019 05:04:15 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5E6A5A4065; Thu, 28 Nov 2019 05:04:13 +0000 (GMT) Received: from in.ibm.com (unknown [9.199.59.121]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Thu, 28 Nov 2019 05:04:13 +0000 (GMT) Date: Thu, 28 Nov 2019 10:34:11 +0530 From: Bharata B Rao To: linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, linux-mm@kvack.org Cc: paulus@au1.ibm.com, aneesh.kumar@linux.vnet.ibm.com, jglisse@redhat.com, cclaudio@linux.ibm.com, linuxram@us.ibm.com, sukadev@linux.vnet.ibm.com, hch@lst.de, Hugh Dickins Subject: Re: [PATCH v11 0/7] KVM: PPC: Driver to manage pages of secure guest Reply-To: bharata@linux.ibm.com References: <20191125030631.7716-1-bharata@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191125030631.7716-1-bharata@linux.ibm.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-TM-AS-GCONF: 00 x-cbid: 19112805-0028-0000-0000-000003C0F216 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19112805-0029-0000-0000-00002483FB30 Message-Id: <20191128050411.GF23438@in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-11-27_07:2019-11-27,2019-11-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 mlxscore=0 suspectscore=0 spamscore=0 phishscore=0 mlxlogscore=999 bulkscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1911280042 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Nov 25, 2019 at 08:36:24AM +0530, Bharata B Rao wrote: > Hi, > > This is the next version of the patchset that adds required support > in the KVM hypervisor to run secure guests on PEF-enabled POWER platforms. > Here is a fix for the issue Hugh identified with the usage of ksm_madvise() in this patchset. It applies on top of this patchset. ---- >From 8a4d769bf4c61f921c79ce68923be3c403bd5862 Mon Sep 17 00:00:00 2001 From: Bharata B Rao Date: Thu, 28 Nov 2019 09:31:54 +0530 Subject: [PATCH 1/1] KVM: PPC: Book3S HV: Take write mmap_sem when calling ksm_madvise In order to prevent the device private pages (that correspond to pages of secure guest) from participating in KSM merging, H_SVM_PAGE_IN calls ksm_madvise() under read version of mmap_sem. However ksm_madvise() needs to be under write lock, fix this. Signed-off-by: Bharata B Rao --- arch/powerpc/kvm/book3s_hv_uvmem.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index f24ac3cfb34c..2de264fc3156 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -46,11 +46,10 @@ * * Locking order * - * 1. srcu_read_lock(&kvm->srcu) - Protects KVM memslots - * 2. down_read(&kvm->mm->mmap_sem) - find_vma, migrate_vma_pages and helpers - * 3. mutex_lock(&kvm->arch.uvmem_lock) - protects read/writes to uvmem slots - * thus acting as sync-points - * for page-in/out + * 1. kvm->srcu - Protects KVM memslots + * 2. kvm->mm->mmap_sem - find_vma, migrate_vma_pages and helpers, ksm_madvise + * 3. kvm->arch.uvmem_lock - protects read/writes to uvmem slots thus acting + * as sync-points for page-in/out */ /* @@ -344,7 +343,7 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm) static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start, unsigned long end, unsigned long gpa, struct kvm *kvm, - unsigned long page_shift) + unsigned long page_shift, bool *downgrade) { unsigned long src_pfn, dst_pfn = 0; struct migrate_vma mig; @@ -360,8 +359,15 @@ kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start, mig.src = &src_pfn; mig.dst = &dst_pfn; + /* + * We come here with mmap_sem write lock held just for + * ksm_madvise(), otherwise we only need read mmap_sem. + * Hence downgrade to read lock once ksm_madvise() is done. + */ ret = ksm_madvise(vma, vma->vm_start, vma->vm_end, MADV_UNMERGEABLE, &vma->vm_flags); + downgrade_write(&kvm->mm->mmap_sem); + *downgrade = true; if (ret) return ret; @@ -456,6 +462,7 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, unsigned long flags, unsigned long page_shift) { + bool downgrade = false; unsigned long start, end; struct vm_area_struct *vma; int srcu_idx; @@ -476,7 +483,7 @@ kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, ret = H_PARAMETER; srcu_idx = srcu_read_lock(&kvm->srcu); - down_read(&kvm->mm->mmap_sem); + down_write(&kvm->mm->mmap_sem); start = gfn_to_hva(kvm, gfn); if (kvm_is_error_hva(start)) @@ -492,12 +499,16 @@ kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, if (!vma || vma->vm_start > start || vma->vm_end < end) goto out_unlock; - if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift)) + if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift, + &downgrade)) ret = H_SUCCESS; out_unlock: mutex_unlock(&kvm->arch.uvmem_lock); out: - up_read(&kvm->mm->mmap_sem); + if (downgrade) + up_read(&kvm->mm->mmap_sem); + else + up_write(&kvm->mm->mmap_sem); srcu_read_unlock(&kvm->srcu, srcu_idx); return ret; } -- 2.21.0