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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C018C04A68 for ; Thu, 28 Jul 2022 15:18:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231731AbiG1PS5 (ORCPT ); Thu, 28 Jul 2022 11:18:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231775AbiG1PSw (ORCPT ); Thu, 28 Jul 2022 11:18:52 -0400 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD70B6050B for ; Thu, 28 Jul 2022 08:18:40 -0700 (PDT) Received: from zn.tnic (p57969665.dip0.t-ipconnect.de [87.150.150.101]) (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 361861EC0567; Thu, 28 Jul 2022 17:18:35 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1659021515; 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=RFFgyhldhcIGPI4uosV2Lk0agZN008XdlmOLfQBHDwI=; b=IXY5tKY2fhce9cZyBx/2LwD6jSvP4zibbUINYX2Y8OWPXBsQNI8AyVaVYO6q+Jj0rbt8zR miRpI3YCr7RFJc2+KPQedbpflLR5ERjOEyy7F2wZJ57KD18QCXN0F2WdGDjxXjYZKh6ZNo 9bK3hc1ARgwwsFdy+P3SHZZEb9EBkGw= Date: Thu, 28 Jul 2022 17:18:31 +0200 From: Borislav Petkov To: Dimitri John Ledkov , Thadeu Lima de Souza Cascardo Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Peter Zijlstra Subject: Re: [PATCH] x86/bugs: Do not enable IBPB at firmware entry when IBPB is not available Message-ID: References: <20220728122602.2500509-1-cascardo@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 28, 2022 at 03:33:35PM +0100, Dimitri John Ledkov wrote: > Azure public cloud (so it is Azure custom hyper-v hypervisor) these > instance types https://docs.microsoft.com/en-us/azure/virtual-machines/dav4-dasv4-series Thank you both for the info. Virt is an awful piece of sh*t when it goes and emulates all kinds of imaginary CPUs. And AMD machine *without* an IBPB which is affected by retbleed. Well, f*ck that. Does that say somewhere on azure that those guests need to even enable the mitigation or does the HV mitigate it for them? Because I wouldn't mind to simply disable the mitigation when on a hypervisor which doesn't support IBPB. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette