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=-10.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=no 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 5A1C0C4320A for ; Fri, 13 Aug 2021 16:28:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CC81610EA for ; Fri, 13 Aug 2021 16:28:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235597AbhHMQ3S (ORCPT ); Fri, 13 Aug 2021 12:29:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235642AbhHMQ3O (ORCPT ); Fri, 13 Aug 2021 12:29:14 -0400 Received: from mail-pl1-x62b.google.com (mail-pl1-x62b.google.com [IPv6:2607:f8b0:4864:20::62b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4EDFCC061756 for ; Fri, 13 Aug 2021 09:28:47 -0700 (PDT) Received: by mail-pl1-x62b.google.com with SMTP id e19so12645568pla.10 for ; Fri, 13 Aug 2021 09:28:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=5vsrCAhIhqleSp4ilnt79j6IYc6DztFKdxcos4U/Zdw=; b=s/gPWOK8ezdqks7mEUKZQGuY3ur/s9nmz5Xm799RPiVLlhDeWVeLaq4jwY6wGUpZzk kfQBYmld7FNccLGlURTq+4X5SM0Ld67qddVGTEfkj/tWtjysVvvlgA9C5m3Fkd/bpjp/ MU6i66OntDLzok1dUjkKiGJO+DggV18HL7D+s7JnFal3Pi8D4HjcE9JwyuF7DVt7YChG uZ9Uv4Wg0ycik3MJ+eAR6cidd+x9kNOjv4dOGPtG1xUGr8TFzJYENi8fjK+8UyN3tbmS rJdtxUQgeUwXjnACaHFBTrHv7iCLgOiVCAPRsmuN5zOCQFBrMI5BUO/2T2vUe5ahZfjp zrMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=5vsrCAhIhqleSp4ilnt79j6IYc6DztFKdxcos4U/Zdw=; b=paOiovrySwolCD3+G9N2jaQhm7XA1JaRuK0V41IBWFJS908cVLQPqsD/I1MrXNHE4V wrqG7vgiUlCTAezd/3qIdiihq497xDQopuRhFLoelqIghZD+H8n2riSyFmz+KFkdfPK6 lWDxNIv2SDarIGPpYiEg8s21ha4Q/ypj5lzYPN9JMahq6quN6uVz690BUZp0sTnLik7l AxCMelrvnBKEzsXb7a5Uyq4A/MSUQr9ZB3hMX8c6d+YAO0wiJjQzjf4VtK3Umfxwp+3p cs7x1lEndsjKeTVFRN6iRkgCQsdPJfD2lnn2eBu1vBje6we7SDEbNaeWgtJ+f9Cs6o9r zcNA== X-Gm-Message-State: AOAM530L0/lKI6jBPN64Qm4NDCOKbhfXrRetOuXJ6s5Nst8+Y3vWMzbK CoHnnWeV5sRL/9OiYnLB2F9A0Q== X-Google-Smtp-Source: ABdhPJzFcDg42Qi/QLxlT+AItPtHajHKKItsai4wbDeuQpZVXo0+ztFHB94T39wdHTdSuIGS4ouPdw== X-Received: by 2002:aa7:8a04:0:b029:3e0:ec4a:6e65 with SMTP id m4-20020aa78a040000b02903e0ec4a6e65mr3227176pfa.47.1628872126672; Fri, 13 Aug 2021 09:28:46 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id f6sm2745044pfv.69.2021.08.13.09.28.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Aug 2021 09:28:45 -0700 (PDT) Date: Fri, 13 Aug 2021 16:28:40 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, isaku.yamahata@intel.com, David Matlack , peterx@redhat.com Subject: Re: [PATCH 02/16] KVM: x86: clamp host mapping level to max_level in kvm_mmu_max_mapping_level Message-ID: References: <20210807134936.3083984-1-pbonzini@redhat.com> <20210807134936.3083984-3-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210807134936.3083984-3-pbonzini@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 07, 2021, Paolo Bonzini wrote: > This patch started as a way to make kvm_mmu_hugepage_adjust a bit simpler, > in preparation for switching it to struct kvm_page_fault, but it does > fix a microscopic bug in zapping collapsible PTEs. I think this also fixes a bug where userspace backs guest memory with a 1gb hugepage but only assigns a subset of the page to the guest. 1gb pages would be disallowed by the memslot, but not 2mb. kvm_mmu_max_mapping_level() would fall through to the host_pfn_mapping_level() logic, see the 1gb huge, and map the whole thing into the guest. I can't imagine any userspace would actually do something like that, but the failure mode is serious enough that it warrants a Fixes: + Cc: stable@.