From patchwork Wed Sep 21 03:51:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Collingbourne X-Patchwork-Id: 12983190 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DE42AC6FA82 for ; Wed, 21 Sep 2022 03:54:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Mime-Version: Message-Id:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=58NE+DObGzcGgAcsExfvHlQX0RpCVPKukw1gtKhvvY4=; b=bFB 4//4McC22fdykwnLd5vnq0ColVD+mR1sGpUttOfI7bIgWBUx0E/qC53HHBEkFrU3lro+yS4ZC48/G w6NEpSa/pqZvsZUSkwffbXR27MleCHrKodcyjkozeXzl0hMHAqgDi0hmduPFVEOk06iGe2+qTm9uk sGYNWLV+PA8sME3FDbcfka24/fpKSTIwiLNl42fRAE+REewGtwUqmplAa5t6zAGhbhYU+M4he6h/U KRqczV9eENNLTyY8HCUeVrNi2/vpB9nrEB5JPwbSs3b0sh1Zky+Pn969yrfimAHzRVgFR8VuQIQi1 RKxtHCCOQYV5oijTsOnh8gPICw7Af8Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oaqnE-008fnj-R6; Wed, 21 Sep 2022 03:53:00 +0000 Received: from mail-yb1-xb49.google.com ([2607:f8b0:4864:20::b49]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oaqnA-008flz-VH for linux-arm-kernel@lists.infradead.org; Wed, 21 Sep 2022 03:52:58 +0000 Received: by mail-yb1-xb49.google.com with SMTP id p12-20020a259e8c000000b006958480b858so4055628ybq.12 for ; Tue, 20 Sep 2022 20:52:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:mime-version:message-id:date:from:to:cc:subject :date; bh=MzLSXN9659oMN46VAD3QaEqmFer6u1utIpA2UG+9EdQ=; b=teECItsEgFfiTvj51+jcO1iNDgFfQ1pKS0sNjOrJ004BNZAuTGOtdrc+2SXYPpQEOr 1WGJ7RS4jjKQewkJMEdGDYCrhjHTEQkp0b9LaLRRapaVhmUbpOUvZpICfzSfIwCunJ4p 0Q1DUx62655IPzl7V9K7RggL1J+64ahObLuOwj6qQzw1cmFo21eOzv095sOJ+7JiImre 7XJpq78XYQ4vEYYXAl0QHFuYz97QeOt3GTnT6WqlBwIcNTet16bb1UwBhFLd8JBym/Ir T05UcoxEdMMBPXJYC7yvod1Ootxtooo4jVc47DQ7v0TSRG5wWa8MvcH0tTtI8yoA7YI3 +mqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:mime-version:message-id:date:x-gm-message-state :from:to:cc:subject:date; bh=MzLSXN9659oMN46VAD3QaEqmFer6u1utIpA2UG+9EdQ=; b=zK0lrXSEv3XGNsWKM5TZUKDWiBotuVrIJcBPLIc7chyQMsk/D+GnpPkKwtKdkNjIV7 nvuY85iS4ckU8Xla5dbJfrEZ3wRBjkKnBHkohAey27J3A0xgDsYPQ1cyUF4S2YxO2K5M p9UvKLOrQy/mYjGyPtY8yMRAeI85NqXNwy8iH9qHxFgRRRrGy5tDWjbN4BIMHYSC4ret ZQMU0obIr3H8XxjVq7H1mYJ8qXJeoXPxgrcWLD2gukXds4kjOLUW3nkR2LJDSIiWjw/F eY+s8PS8JeYlvx9jL9K4/ppgGCOYevKjule1bkZQYa/K53L+tewHmaMfRDbUHmFLP1Ct WeAg== X-Gm-Message-State: ACrzQf3TAvJRQzxV5IxY96MLCufmZVz8vVcn75NL7k24D5wRILZuycVi SZLt/LwPTG5cbtXM8v6T3DEooOaNSA76+hMrKenZWXV3R38iGW+08ssl+Th5CyRYgdoJzuq4Qrw wBqi1d4QRVRVMugQob6I1qhHOw3TGIOEdfDbEVPvgXN1+wsB/zYZU5koafeNUxtVLrdcX5q6Q X-Google-Smtp-Source: AMsMyM6p1o6DZc1El2WX74JXWnrje6NxwPNf5KdOg0qnIgai24Z40ItJ6/xIIeE3xlynhFeSvJWE/Xs= X-Received: from pcc-desktop.svl.corp.google.com ([2620:15c:2ce:200:1b89:96f1:d30:e3c]) (user=pcc job=sendgmr) by 2002:a81:910:0:b0:349:b5c1:4086 with SMTP id 16-20020a810910000000b00349b5c14086mr22866786ywj.98.1663732373777; Tue, 20 Sep 2022 20:52:53 -0700 (PDT) Date: Tue, 20 Sep 2022 20:51:32 -0700 Message-Id: <20220921035140.57513-1-pcc@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.37.3.968.ga6b4b080e4-goog Subject: [PATCH v4 0/8] KVM: arm64: permit MAP_SHARED mappings with MTE enabled From: Peter Collingbourne To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu Cc: Peter Collingbourne , Cornelia Huck , Catalin Marinas , Will Deacon , Marc Zyngier , Evgenii Stepanov , kvm@vger.kernel.org, Steven Price , Vincenzo Frascino X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220920_205257_043135_8310AE7B X-CRM114-Status: GOOD ( 26.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, This patch series allows VMMs to use shared mappings in MTE enabled guests. The first five patches were taken from Catalin's tree [1] which addressed some review feedback from when they were previously sent out as v3 of this series. The first patch from Catalin's tree makes room for an additional PG_arch_3 flag by making the newer PG_arch_* flags arch-dependent. The next four patches are based on a series that Catalin sent out prior to v3, whose cover letter [2] I quote from below: > This series aims to fix the races between initialising the tags on a > page and setting the PG_mte_tagged flag. Currently the flag is set > either before or after that tag initialisation and this can lead to CoW > copying stale tags. The first patch moves the flag setting after the > tags have been initialised, solving the CoW issue. However, concurrent > mprotect() on a shared mapping may (very rarely) lead to valid tags > being zeroed. > > The second skips the sanitise_mte_tags() call in kvm_set_spte_gfn(), > deferring it to user_mem_abort(). The outcome is that no > sanitise_mte_tags() can be simplified to skip the pfn_to_online_page() > check and only rely on VM_MTE_ALLOWED vma flag that can be checked in > user_mem_abort(). > > The third and fourth patches use PG_arch_3 as a lock for page tagging, > based on Peter Collingbourne's idea of a two-bit lock. > > I think the first patch can be queued but the rest needs some in depth > review and test. With this series (if correct) we could allos MAP_SHARED > on KVM guest memory but this is to be discussed separately as there are > some KVM ABI implications. I rebased Catalin's tree onto -next and added the proposed userspace enablement patches after the series. I've tested it on QEMU as well as on MTE-capable hardware by booting a Linux kernel and userspace under a crosvm with MTE support [3]. [1] git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux devel/mte-pg-flags [2] https://lore.kernel.org/all/20220705142619.4135905-1-catalin.marinas@arm.com/ [3] https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3892141 Catalin Marinas (4): mm: Do not enable PG_arch_2 for all 64-bit architectures arm64: mte: Fix/clarify the PG_mte_tagged semantics KVM: arm64: Simplify the sanitise_mte_tags() logic arm64: mte: Lock a page for MTE tag initialisation Peter Collingbourne (4): mm: Add PG_arch_3 page flag KVM: arm64: unify the tests for VMAs in memslots when MTE is enabled KVM: arm64: permit all VM_MTE_ALLOWED mappings with MTE enabled Documentation: document the ABI changes for KVM_CAP_ARM_MTE Documentation/virt/kvm/api.rst | 5 ++- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/mte.h | 65 ++++++++++++++++++++++++++++++- arch/arm64/include/asm/pgtable.h | 4 +- arch/arm64/kernel/cpufeature.c | 4 +- arch/arm64/kernel/elfcore.c | 2 +- arch/arm64/kernel/hibernate.c | 2 +- arch/arm64/kernel/mte.c | 16 ++++---- arch/arm64/kvm/guest.c | 18 +++++---- arch/arm64/kvm/mmu.c | 55 +++++++++++--------------- arch/arm64/mm/copypage.c | 7 +++- arch/arm64/mm/fault.c | 4 +- arch/arm64/mm/mteswap.c | 13 ++++--- fs/proc/page.c | 3 +- include/linux/kernel-page-flags.h | 1 + include/linux/page-flags.h | 3 +- include/trace/events/mmflags.h | 9 +++-- mm/Kconfig | 8 ++++ mm/huge_memory.c | 3 +- 19 files changed, 152 insertions(+), 71 deletions(-)