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=-5.8 required=3.0 tests=BAYES_00,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 522E8C63697 for ; Tue, 17 Nov 2020 18:28:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFC972222E for ; Tue, 17 Nov 2020 18:28:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="l9Od5R41" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731369AbgKQS2K (ORCPT ); Tue, 17 Nov 2020 13:28:10 -0500 Received: from mail.skyhub.de ([5.9.137.197]:54698 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726504AbgKQS2K (ORCPT ); Tue, 17 Nov 2020 13:28:10 -0500 Received: from zn.tnic (p200300ec2f101300378e6ae0a1a779ec.dip0.t-ipconnect.de [IPv6:2003:ec:2f10:1300:378e:6ae0:a1a7:79ec]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id E864D1EC0402; Tue, 17 Nov 2020 19:28:08 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1605637689; 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:in-reply-to:in-reply-to: references:references; bh=Iv/oL4ZsWEgCGT0FNKjRrZW4WXNcn8Mky6gXuPvvyGE=; b=l9Od5R41YU4mUUa8RhDTgtegthh9VlqpQA2w1err2WGyBufdx+6aOD8Rsyt71j1rfRiiqH dsioFyo0Bg/PZgPkIuPg9qn+hxAggQy4i/z1c82OYk+h+ouxN2xKUwQhJgT7XvjmO0RB1T LVjhaj10H/o7WaYNfwlUdXhqitnnxDQ= Date: Tue, 17 Nov 2020 19:28:09 +0100 From: Borislav Petkov To: Alexandre Chartre Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, thomas.lendacky@amd.com, jroedel@suse.de, konrad.wilk@oracle.com, jan.setjeeilers@oracle.com, junaids@google.com, oweisse@google.com, rppt@linux.vnet.ibm.com, graf@amazon.de, mgross@linux.intel.com, kuzuno@gmail.com Subject: Re: [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code Message-ID: <20201117182809.GK5719@zn.tnic> References: <20201116144757.1920077-1-alexandre.chartre@oracle.com> <20201116201711.GE1131@zn.tnic> <44a88648-738a-4a4b-9c25-6b70000e037c@oracle.com> <20201117165539.GG5719@zn.tnic> <890f6b7e-a268-2257-edcb-5eacc7db3d8e@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <890f6b7e-a268-2257-edcb-5eacc7db3d8e@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 17, 2020 at 07:12:07PM +0100, Alexandre Chartre wrote: > Yes. L1TF/MDS allow some inter cpu-thread attacks which are not mitigated at > the moment. In particular, this allows a guest VM to attack another guest VM > or the host kernel running on a sibling cpu-thread. Core Scheduling will > mitigate the guest-to-guest attack but not the guest-to-host attack. I see in vmx_vcpu_enter_exit(): /* L1D Flush includes CPU buffer clear to mitigate MDS */ if (static_branch_unlikely(&vmx_l1d_should_flush)) vmx_l1d_flush(vcpu); else if (static_branch_unlikely(&mds_user_clear)) mds_clear_cpu_buffers(); Is that not enough? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette