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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 84058C433B4 for ; Mon, 17 May 2021 14:16:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6881F613EC for ; Mon, 17 May 2021 14:16:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235507AbhEQOR5 (ORCPT ); Mon, 17 May 2021 10:17:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:57360 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235543AbhEQOPN (ORCPT ); Mon, 17 May 2021 10:15:13 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1621260836; h=from:from:reply-to: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=lwE+T0c+xlHjc49FEylrM2BvekW9eKLArf9QaPrjeEw=; b=MWgi0KHh0Jd9DgsygqlTrv7WF3mMH+tR979KiKRtH17JWUc0vjATnRHwRxkz7WqJdOap+b gDoh6thuXBQePPtv7wwg2NWmEnhuBeBhzRWG89YqvaBML/HVasdng0lVHp1Ff7jBJ4yMWg mOhDSclmEAjvafp9vOBWrPvrvpMt/nY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4BF45B231; Mon, 17 May 2021 14:13:56 +0000 (UTC) Subject: Re: [PATCH v2 1/4] usb: early: Avoid using DbC if already enabled To: Connor Davis Cc: Jann Horn , Lee Jones , Chunfeng Yun , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, Greg Kroah-Hartman References: <8ccce25a-e3ca-cb30-f6a3-f9243a85a49b@suse.com> <16400ee4-4406-8b26-10c0-a423b2b1fed0@gmail.com> From: Jan Beulich Message-ID: Date: Mon, 17 May 2021 16:13:55 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <16400ee4-4406-8b26-10c0-a423b2b1fed0@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17.05.2021 15:48, Connor Davis wrote: > > On 5/17/21 3:32 AM, Jan Beulich wrote: >> On 14.05.2021 02:56, Connor Davis wrote: >>> Check if the debug capability is enabled in early_xdbc_parse_parameter, >>> and if it is, return with an error. This avoids collisions with whatever >>> enabled the DbC prior to linux starting. >> Doesn't this go too far and prevent use even if firmware (perhaps >> mistakenly) left it enabled? > > Yes, but how is one supposed to distinguish the broken firmware and > non-broken > > firmware cases? Well, a first step might be to only check if running virtualized. And then if your running virtualized, there might be a way to inquire the hypervisor? Jan