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 9A87BC43217 for ; Thu, 9 Sep 2021 15:00:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4279C61131 for ; Thu, 9 Sep 2021 15:00:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4279C61131 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 1684B6B0072; Thu, 9 Sep 2021 10:59:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1150E6B0073; Thu, 9 Sep 2021 10:59:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EF6C1900002; Thu, 9 Sep 2021 10:59:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0178.hostedemail.com [216.40.44.178]) by kanga.kvack.org (Postfix) with ESMTP id DF2AD6B0072 for ; Thu, 9 Sep 2021 10:59:58 -0400 (EDT) Received: from smtpin35.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 7A14E2D38A for ; Thu, 9 Sep 2021 14:59:58 +0000 (UTC) X-FDA: 78568344876.35.D715D2C Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf03.hostedemail.com (Postfix) with ESMTP id 3E4363000096 for ; Thu, 9 Sep 2021 14:59:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631199597; 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=Xs2SVTgBq7Vx1ySawCfwpzsExlEbPS/kiK1uV7V/sfI=; b=UeNNnLU6A2wVYOQ7wXcgcMqx+Q5bBcYrDAAis2CA9jqenKxomMJHmOIwd6O9LaeTb5C/bq eRk+RTLvZsyga0ej6d5GMG/GESmmcc+E9F1w8Y1CEAmYCfaSzHiQz4M+PiGzcaSWSbVyRk axGDW3yFb46F825+o1iIjHH95kQTDNE= 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-492-ItPiY0keN0C6pc0gHxBjsg-1; Thu, 09 Sep 2021 10:59:54 -0400 X-MC-Unique: ItPiY0keN0C6pc0gHxBjsg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E6CAD8145E7; Thu, 9 Sep 2021 14:59:52 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.192.233]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9123869FAE; Thu, 9 Sep 2021 14:59:46 +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 RFC 0/9] s390: fixes, cleanups and optimizations for page table walkers Date: Thu, 9 Sep 2021 16:59:36 +0200 Message-Id: <20210909145945.12192-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 3E4363000096 X-Stat-Signature: 8bx4rynbk9nn3ery1qeq1u3udixohfcm Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=UeNNnLU6; spf=none (imf03.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-HE-Tag: 1631199598-422647 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: 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