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 BB6EBEB64DC for ; Fri, 21 Jul 2023 10:58:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231233AbjGUK57 (ORCPT ); Fri, 21 Jul 2023 06:57:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231148AbjGUK56 (ORCPT ); Fri, 21 Jul 2023 06:57:58 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 173C119AD for ; Fri, 21 Jul 2023 03:57:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689937033; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JCcb9xtScqAyMOStlm7ewhQnyFA6r02pOvdu3ozJ8ms=; b=CfDUw4n5j9Ub8zU/uGCccEihQ3s/RFlSzrHXicFgigg9iXRpcJsjAkzayq/qzqV7eXWNbF TgYL2U0/RTkrjVJjgxihUYvvc8ehJ/QT0O8zUK7bCf7VwiS31imZHJUAZyB/kGNlg1HGkq JyrMHOhm3ERua6VGu9U+jHpmsjE6Utg= Received: from mail-ej1-f72.google.com (mail-ej1-f72.google.com [209.85.218.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-222-8zZ7z3ZjO8ekX3_wagLOBA-1; Fri, 21 Jul 2023 06:57:11 -0400 X-MC-Unique: 8zZ7z3ZjO8ekX3_wagLOBA-1 Received: by mail-ej1-f72.google.com with SMTP id a640c23a62f3a-98e1085308eso338395466b.0 for ; Fri, 21 Jul 2023 03:57:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689937031; x=1690541831; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=JCcb9xtScqAyMOStlm7ewhQnyFA6r02pOvdu3ozJ8ms=; b=ANH3I6AL+C7noqDw9WowjDNsmAlFW6a4QJwFlme/kOLN9ILMG5eKvmDvWskEMTc+yR yOFrZamCT0nbeDfVVXqHjS8xfQPhc/UwqwX6bYobRpDWifFHVmsvGpYWGJL+RUSMyEi+ rzCjDJ6kgnVWv6Vr3U2V3+JjS+v6J85OGe01ZuSPw2MICXW23jgcxOzkdfl0GxeaiFe6 9dPOfOqk3z8EZUb54kuvVXPEk0WkkoECgyaUw8xmXG+TFu0va38Sq5Mw+Zq21n1s0rqF yJwqT+KgO9ywRKAwPFSKHK87IF0ORZuUlx8PDauOSvYNH1/+34ygQmdTabTUgEg5USy+ 4EIw== X-Gm-Message-State: ABy/qLZDeRxgIfCTYurLH8M5siUhmlHv73Qxkakfj9MLZMQcr9GTA/KJ YZDPseUQrR56NL7tkuHQadUoMqldMR7xqHPR3ai0vZOaOECeV8s24AMew3llnqdHpsH5jV3KZ0+ sPzNOSIJuUio/NYXDciwCGZIJZakvCz9WbKr/ X-Received: by 2002:a17:907:d8a:b0:991:d414:d889 with SMTP id go10-20020a1709070d8a00b00991d414d889mr8230221ejc.15.1689937030822; Fri, 21 Jul 2023 03:57:10 -0700 (PDT) X-Google-Smtp-Source: APBJJlHG8R7IreJRTfdc0Wq/Yo7PIzOhZZy/jcnGLgxDY0N1OVv0CFUqys6sH346KYqEVj6MNTbrkQ== X-Received: by 2002:a17:907:d8a:b0:991:d414:d889 with SMTP id go10-20020a1709070d8a00b00991d414d889mr8230204ejc.15.1689937030548; Fri, 21 Jul 2023 03:57:10 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:9af8:e5f5:7516:fa89? ([2001:b07:6468:f312:9af8:e5f5:7516:fa89]) by smtp.googlemail.com with ESMTPSA id f21-20020a170906049500b0099364d9f0e9sm2025435eja.102.2023.07.21.03.57.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 Jul 2023 03:57:09 -0700 (PDT) Message-ID: <0c033063-5d20-4522-87e2-80ad3cca3602@redhat.com> Date: Fri, 21 Jul 2023 12:57:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [RFC PATCH v11 08/29] KVM: Introduce per-page memory attributes To: Sean Christopherson , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-9-seanjc@google.com> From: Paolo Bonzini In-Reply-To: <20230718234512.1690985-9-seanjc@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: On 7/19/23 01:44, Sean Christopherson wrote: > From: Chao Peng > > In confidential computing usages, whether a page is private or shared is > necessary information for KVM to perform operations like page fault > handling, page zapping etc. There are other potential use cases for > per-page memory attributes, e.g. to make memory read-only (or no-exec, > or exec-only, etc.) without having to modify memslots. > > Introduce two ioctls (advertised by KVM_CAP_MEMORY_ATTRIBUTES) to allow > userspace to operate on the per-page memory attributes. > - KVM_SET_MEMORY_ATTRIBUTES to set the per-page memory attributes to > a guest memory range. > - KVM_GET_SUPPORTED_MEMORY_ATTRIBUTES to return the KVM supported > memory attributes. > > Use an xarray to store the per-page attributes internally, with a naive, > not fully optimized implementation, i.e. prioritize correctness over > performance for the initial implementation. > > Because setting memory attributes is roughly analogous to mprotect() on > memory that is mapped into the guest, zap existing mappings prior to > updating the memory attributes. Opportunistically provide an arch hook > for the post-set path (needed to complete invalidation anyways) in > anticipation of x86 needing the hook to update metadata related to > determining whether or not a given gfn can be backed with various sizes > of hugepages. > > It's possible that future usages may not require an invalidation, e.g. > if KVM ends up supporting RWX protections and userspace grants _more_ > protections, but again opt for simplicity and punt optimizations to > if/when they are needed. > > Suggested-by: Sean Christopherson > Link: https://lore.kernel.org/all/Y2WB48kD0J4VGynX@google.com > Cc: Fuad Tabba > Signed-off-by: Chao Peng > Co-developed-by: Sean Christopherson > Signed-off-by: Sean Christopherson Reviewed-by: Paolo Bonzini