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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 EBF86C4332F for ; Tue, 14 Sep 2021 09:02:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D176A6112E for ; Tue, 14 Sep 2021 09:02:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230416AbhINJD4 (ORCPT ); Tue, 14 Sep 2021 05:03:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:33926 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229868AbhINJDy (ORCPT ); Tue, 14 Sep 2021 05:03:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631610157; 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=d9zHzAE5JRRNzn4tPguLuhYSUPQr1fd/jH5EtFVUE3c=; b=QAbt76ZBn3ZTIsTesDpADF+Lf4xTewBwxcV/pBc137OsigI6iBWuRXA+MEOJc7S643TMm4 Ky5P4jJ4w5OlrLzklw9Yo/GmyZ0EP8956iVCscAv7fdve4ofZwa6pH4LRFy4ONDpazzA2k QYbs4UvLGFM9ZAZEvjWNWAPVSBlKWLE= 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-511-6ZFRKCtGND6AYxhtycmzbw-1; Tue, 14 Sep 2021 05:02:36 -0400 X-MC-Unique: 6ZFRKCtGND6AYxhtycmzbw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BF157800FF4; Tue, 14 Sep 2021 09:02:32 +0000 (UTC) Received: from starship (unknown [10.35.206.50]) by smtp.corp.redhat.com (Postfix) with ESMTP id 668835D9DC; Tue, 14 Sep 2021 09:02:29 +0000 (UTC) Message-ID: <9585f1387b2581d30b74cd163a9aac2adbd37a93.camel@redhat.com> Subject: Re: [RFC PATCH 3/3] nSVM: use svm->nested.save to load vmcb12 registers and avoid TOC/TOU races From: Maxim Levitsky To: Emanuele Giuseppe Esposito , kvm@vger.kernel.org Cc: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org Date: Tue, 14 Sep 2021 12:02:28 +0300 In-Reply-To: <73b5a5bb-48f2-3a08-c76b-a82b5b69c406@redhat.com> References: <20210903102039.55422-1-eesposit@redhat.com> <20210903102039.55422-4-eesposit@redhat.com> <21d2bf8c4e3eb3fc5d297fd13300557ec686b625.camel@redhat.com> <73b5a5bb-48f2-3a08-c76b-a82b5b69c406@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2021-09-14 at 10:20 +0200, Emanuele Giuseppe Esposito wrote: > > On 12/09/2021 12:42, Maxim Levitsky wrote: > > > > > > - if (!nested_vmcb_valid_sregs(vcpu, &vmcb12->save) || > > > + if (!nested_vmcb_valid_sregs(vcpu, &svm->nested.save) || > > > !nested_vmcb_check_controls(vcpu, &svm->nested.ctl)) { > > If you use a different struct for the copied fields, then it makes > > sense IMHO to drop the 'control' parameter from nested_vmcb_check_controls, > > and just use the svm->nested.save there directly. > > > > Ok, what you say in patch 2 makes sense to me. I can create a new struct > vmcb_save_area_cached, but I need to keep nested.ctl because 1) it is > used also elsewhere, and different fields from the one checked here are > read/set and 2) using another structure (or the same Yes, keep nested.ctl, since vast majority of the fields are copied I think. Best regards, Maxim Levitsky > vmcb_save_area_cached) in its place would just duplicate the same fields > of nested.ctl, creating even more confusion and possible inconsistency. > > Let me know if you disagree. > > Thank you, > Emanuele >