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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 DF91DC433E6 for ; Wed, 23 Dec 2020 10:52:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3FE820867 for ; Wed, 23 Dec 2020 10:52:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728301AbgLWKvv (ORCPT ); Wed, 23 Dec 2020 05:51:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57992 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726022AbgLWKvv (ORCPT ); Wed, 23 Dec 2020 05:51:51 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80306C0613D3 for ; Wed, 23 Dec 2020 02:51:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Message-ID:From:CC:To:Subject: Content-Transfer-Encoding:Content-Type:MIME-Version:References:In-Reply-To: Date:Sender:Reply-To:Content-ID:Content-Description; bh=Lt09kCHgkUzbRMUDr+ddXdoZT19yUAB8i/xZm9rm+qg=; b=F/bdsJM7RiNIBeVhSTwWfCvHeF WeuJH8G7kEHpWs5/BtnezHiqbC3/19LBNJg1hddX4OYIExOoBYCjcmo4Gu/TaRRSvAGWENPzec0/h /apx/ZueAr/o6gPPpaMy+B8JbEYLzOO2FpzwGpIIwGJu4mHfupBEuw5lu3fygHrConpnIB1+dMaSX mCckB1YAde5+bCbGemCgZDqRvCYqyw3DcTJIvA8isJ4Wb0lCC2MhwjiI5pcdnAdsSGNIHqCNa7JKm 84MhC5SGFCIo7e3qRB6ZcXzUvGmJ0aRWUmhlUnvr+p0aS+CR8XZFpKAafacqYRWuCd0H4Yr7Usozt 62UkOWgw==; Received: from [2a01:4c8:1070:1acd:89a9:a720:68b3:8621] by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1ks1jW-0007GB-N1; Wed, 23 Dec 2020 10:51:07 +0000 Date: Wed, 23 Dec 2020 10:51:00 +0000 User-Agent: K-9 Mail for Android In-Reply-To: <20201223083644.GC27350@infradead.org> References: <20201214083905.2017260-1-dwmw2@infradead.org> <20201214083905.2017260-4-dwmw2@infradead.org> <20201223083644.GC27350@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v3 03/17] KVM: x86/xen: intercept xen hypercalls if enabled To: Christoph Hellwig CC: kvm@vger.kernel.org, Paolo Bonzini , Ankur Arora , Joao Martins , Boris Ostrovsky , Sean Christopherson , graf@amazon.com, iaslan@amazon.de, pdurrant@amazon.com, aagch@amazon.com, fandree@amazon.com From: David Woodhouse Message-ID: <90BDE706-0427-495C-AD34-F618B5D505DE@infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 23 December 2020 08:36:44 GMT, Christoph Hellwig = wrote: >I think all the Xen support code should be conditional on a new config >option so that normal configs don't have to build the code (and open >potential attack vectors)=2E None of this is usable by the guest (as an attack vector or otherwise) unl= ess explicitly enabled by the VMM=2E And for clock stuff it's even using th= e *same* functions that are used for native KVM guests, just parameterised = a little for the different locations=2E I saw the previous discussion but didn't really think it was worth adding = yet another build time option for the kernel=2E Even when I add event channel support I plan to use the same user_cmpxchg = functionality to clean up the KVM steal time handling and even that part wo= n't be Xen-specific=2E --=20 Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E