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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 7BF7AC433F5 for ; Thu, 9 Sep 2021 16:23:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 25331611CB for ; Thu, 9 Sep 2021 16:23:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 25331611CB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id DB6386B0072; Thu, 9 Sep 2021 12:23:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D66906B0073; Thu, 9 Sep 2021 12:23:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C54F6900002; Thu, 9 Sep 2021 12:23:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0126.hostedemail.com [216.40.44.126]) by kanga.kvack.org (Postfix) with ESMTP id B2A516B0072 for ; Thu, 9 Sep 2021 12:23:43 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 616C630158 for ; Thu, 9 Sep 2021 16:23:43 +0000 (UTC) X-FDA: 78568555926.25.6ADA496 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf22.hostedemail.com (Postfix) with ESMTP id 20EDF1905 for ; Thu, 9 Sep 2021 16:23:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631204622; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=FZ2lw8Ps4o19sLYGx4L6VEw4MqECL9A7ahGOfDcjR0g=; b=S1jUZEpQswf2xYNXfiBqYZvcsF9jqE4tCoL2LQ5dIcF3OI5kwLyrUAd/vuaEwroxP66Xtb i8oP60d2CCjO/wHEVIw8gCInDek7CSgdJUvSz+3Lg2Gsdk81kYFmnDAU77wQhVJ1hMq7un g5g2TZl+BF73KozVRUr6DkcneFj33Og= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-562-2jRzvHDMMeGlCNaCTbIEsQ-1; Thu, 09 Sep 2021 12:23:41 -0400 X-MC-Unique: 2jRzvHDMMeGlCNaCTbIEsQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0C38F802C89; Thu, 9 Sep 2021 16:22:53 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.192.233]) by smtp.corp.redhat.com (Postfix) with ESMTP id ED2EB18FD2; Thu, 9 Sep 2021 16:22:49 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , Christian Borntraeger , Janosch Frank , Cornelia Huck , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Niklas Schnelle , Gerald Schaefer , Ulrich Weigand Subject: [PATCH resend RFC 0/9] s390: fixes, cleanups and optimizations for page table walkers Date: Thu, 9 Sep 2021 18:22:39 +0200 Message-Id: <20210909162248.14969-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Stat-Signature: bmjijfmd3kibzf13ebubczqtu67h9kah Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=S1jUZEpQ; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf22.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 20EDF1905 X-HE-Tag: 1631204622-145404 Content-Transfer-Encoding: quoted-printable 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: Resend because I missed ccing people on the actual patches ... RFC because the patches are essentially untested and I did not actually try to trigger any of the things these patches are supposed to fix. It merely matches my current understanding (and what other code does :) ). I did compile-test as far as possible. After learning more about the wonderful world of page tables and their interaction with the mmap_sem and VMAs, I spotted some issues in our page table walkers that allow user space to trigger nasty behavior when playing dirty tricks with munmap() or mmap() of hugetlb. While some issue= s should be hard to trigger, others are fairly easy because we provide conventient interfaces (e.g., KVM_S390_GET_SKEYS and KVM_S390_SET_SKEYS). Future work: - Don't use get_locked_pte() when it's not required to actually allocate page tables -- similar to how storage keys are now handled. Examples ar= e get_pgste() and __gmap_zap. - Don't use get_locked_pte() and instead let page fault logic allocate pa= ge tables when we actually do need page tables -- also, similar to how storage keys are now handled. Examples are set_pgste_bits() and pgste_perform_essa(). - Maybe switch to mm/pagewalk.c to avoid custom page table walkers. For __gmap_zap() that's very easy. Cc: Christian Borntraeger Cc: Janosch Frank Cc: Cornelia Huck Cc: Claudio Imbrenda Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Niklas Schnelle Cc: Gerald Schaefer Cc: Ulrich Weigand David Hildenbrand (9): s390/gmap: validate VMA in __gmap_zap() s390/gmap: don't unconditionally call pte_unmap_unlock() in __gmap_zap() s390/mm: validate VMA in PGSTE manipulation functions s390/mm: fix VMA and page table handling code in storage key handling functions s390/uv: fully validate the VMA before calling follow_page() s390/pci_mmio: fully validate the VMA before calling follow_pte() s390/mm: no need for pte_alloc_map_lock() if we know the pmd is present s390/mm: optimize set_guest_storage_key() s390/mm: optimize reset_guest_reference_bit() arch/s390/kernel/uv.c | 2 +- arch/s390/mm/gmap.c | 11 +++- arch/s390/mm/pgtable.c | 109 +++++++++++++++++++++++++++------------ arch/s390/pci/pci_mmio.c | 4 +- 4 files changed, 89 insertions(+), 37 deletions(-) base-commit: 7d2a07b769330c34b4deabeed939325c77a7ec2f --=20 2.31.1