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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 1D7B6C07E85 for ; Fri, 7 Dec 2018 16:48:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DC40E2081C for ; Fri, 7 Dec 2018 16:48:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DC40E2081C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726135AbeLGQso (ORCPT ); Fri, 7 Dec 2018 11:48:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34960 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726034AbeLGQsn (ORCPT ); Fri, 7 Dec 2018 11:48:43 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CF71430DDBD1; Fri, 7 Dec 2018 16:48:43 +0000 (UTC) Received: from localhost (ovpn-116-57.gru2.redhat.com [10.97.116.57]) by smtp.corp.redhat.com (Postfix) with ESMTP id 699EF7D962; Fri, 7 Dec 2018 16:48:39 +0000 (UTC) Date: Fri, 7 Dec 2018 14:48:37 -0200 From: Eduardo Habkost To: Konrad Rzeszutek Wilk Cc: Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , kvm@vger.kernel.org, Jim Mattson , x86@kernel.org, linux-kernel@vger.kernel.org, KarimAllah Ahmed , David Woodhouse Subject: Re: [PATCH] kvm: x86: Report STIBP on GET_SUPPORTED_CPUID Message-ID: <20181207164837.GE7395@habkost.net> References: <20181205191956.31480-1-ehabkost@redhat.com> <20181205220206.GA16013@char.us.oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181205220206.GA16013@char.us.oracle.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Fri, 07 Dec 2018 16:48:43 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 05, 2018 at 05:02:06PM -0500, Konrad Rzeszutek Wilk wrote: > On Wed, Dec 05, 2018 at 05:19:56PM -0200, Eduardo Habkost wrote: > > Months ago, we have added code to allow direct access to MSR_IA32_SPEC_CTRL > > to the guest, which makes STIBP available to guests. This was implemented > > by commits d28b387fb74d ("KVM/VMX: Allow direct access to > > MSR_IA32_SPEC_CTRL") and b2ac58f90540 ("KVM/SVM: Allow direct access to > > MSR_IA32_SPEC_CTRL"). > > > > However, we never updated GET_SUPPORTED_CPUID to let userspace know that > > STIBP can be enabled in CPUID. Fix that by updating > > Ooops! > > kvm_cpuid_8000_0008_ebx_x86_features and kvm_cpuid_7_0_edx_x86_features. > > Shouldn't there also be a patch in QEMU to use it? (aka, +stibp). I will submit the QEMU patch soon. A patch exists on some downstream QEMU distributions, already, but it was never merged upstream because GET_SUPPORTED_CPUID never supported STIBP in the upstream kernel. (And because in the end it was not used for mitigating Spectre) > > Reviewed-by: Konrad Rzeszutek Wilk Thanks! -- Eduardo