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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 669F4C6FA8B for ; Wed, 21 Sep 2022 03:52:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230322AbiIUDw6 (ORCPT ); Tue, 20 Sep 2022 23:52:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230055AbiIUDwz (ORCPT ); Tue, 20 Sep 2022 23:52:55 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FF0626578 for ; Tue, 20 Sep 2022 20:52:54 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id v5-20020a2583c5000000b006964324be8cso4022048ybm.14 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=PV/xYPa16l4WrDhs0vN0a+xh/6NlHbIxoF59Wsh2hPQZYW6l/g7hDoGAPONXdkJ6qO mHHa3PrO9XbG4UXAXuh4wuzAjd9n3SJlRYKfjRxfamBkh6utpr9eCHQ5cUG2VyexXDkJ 0C0ijwAUWb7GCRsc8hzxK2pSw41npyg1oN57ikVBgpXas7xZFMHq5kK31zYIEyrUv6gF xNF3GCl34uQc16SOHiUe9MEz3JCi04Mqj87/vF7Qz6oWE7gx2bgOfID9+BcKt6h1D3aV HR/Mmz96FcB5Itz9+IdOBsvhfu0nKarZumH1JPKP+6z4wvFucBAMfshSIfppHH4JE3nJ pLuw== X-Gm-Message-State: ACrzQf3sk7e0Z3fsPsoVFVtItVvE5FbA9lHG9FSk759Jnx6s4XhVkxbI hpi7Rl27l5L2AltzqbdaBhNv6hI= 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 Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.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(-) -- 2.37.3.968.ga6b4b080e4-goog