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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 BF8A4C04AB1 for ; Thu, 9 May 2019 16:07:50 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 95BDD2173B for ; Thu, 9 May 2019 16:07:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 95BDD2173B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:57292 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hOlaH-0005IN-Lr for qemu-devel@archiver.kernel.org; Thu, 09 May 2019 12:07:49 -0400 Received: from eggs.gnu.org ([209.51.188.92]:59089) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hOlYi-0004Qj-FS for qemu-devel@nongnu.org; Thu, 09 May 2019 12:06:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hOlYh-0001c4-Aj for qemu-devel@nongnu.org; Thu, 09 May 2019 12:06:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46066) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hOlYh-0001bp-4U for qemu-devel@nongnu.org; Thu, 09 May 2019 12:06:11 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BDA7381259; Thu, 9 May 2019 16:06:09 +0000 (UTC) Received: from Igors-MacBook-Pro (ovpn-204-72.brq.redhat.com [10.40.204.72]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7396C60CC0; Thu, 9 May 2019 16:06:08 +0000 (UTC) Date: Thu, 9 May 2019 18:06:03 +0200 From: Igor Mammedov To: Eduardo Habkost Message-ID: <20190509180603.424c8277@Igors-MacBook-Pro> In-Reply-To: <20190509135617.GH4189@habkost.net> References: <20190422234742.15780-1-ehabkost@redhat.com> <20190509133537.GK7181@orkuz.int.mamuti.net> <20190509135617.GH4189@habkost.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 09 May 2019 16:06:09 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 0/2] i386: "unavailable-features" QOM property X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , Jiri Denemark , qemu-devel@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 9 May 2019 10:56:17 -0300 Eduardo Habkost wrote: > On Thu, May 09, 2019 at 03:35:37PM +0200, Jiri Denemark wrote: > > On Mon, Apr 22, 2019 at 20:47:40 -0300, Eduardo Habkost wrote: > > > Currently, libvirt uses the "filtered-features" QOM property at > > > runtime to ensure no feature was accidentally disabled on VCPUs > > > because it's not available on the host. > > > > > > However, the code for "feature-words" assumes that all missing > > > features have a corresponding CPUID bit, which is not true for > > > MSR-based features like the ones at FEAT_ARCH_CAPABILITIES. > > > > > > We could extend X86CPUFeatureWordInfo to include information > > > about MSR features, but it's impossible to do that while keeping > > > compatibility with clients that (reasonably) expect all elements > > > of "filtered-features" to have the cpuid-* fields. > > > > > > We have a field in "query-cpu-definitions" that already describes > > > all features that are missing on a CPU, including MSR features: > > > CpuDefinitionInfo.unavailable-features. The existing code for > > > building the unavailable-features array even uses > > > X86CPU::filtered_features to build the feature list. > > > > > > This series adds a "unavailable-features" QOM property to X86CPU > > > objects that have the same semantics of "unavailable-features" on > > > query-cpu-definitions. The new property has the same goal of > > > "filtered-features", but is generic enough to let any kind of CPU > > > feature to be listed there without relying on low level details > > > like CPUID leaves or MSR numbers. > > > > Thanks. > > > > Would this unavailable-features property contain only canonical names of > > the features or all possible aliases of all features? For example, > > "tsc-adjust" can also be spelled as "tsc_adjust". When calling > > query-cpu-model-expansion, we have a way to request all variants by > > running full expansion on the result of a previous static expansion. Can > > we get something like this for unavailable-features too? > > I'd like to avoid that, and refer only to the canonical names. Can we deprecate aliases to avoid confusion in future? (there aren't that many of them that used pre-QOM name format)