Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754165AbdDDNo6 (ORCPT ); Tue, 4 Apr 2017 09:44:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51756 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753882AbdDDNoy (ORCPT ); Tue, 4 Apr 2017 09:44:54 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 3BCBC804F3 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=rkrcmar@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 3BCBC804F3 Date: Tue, 4 Apr 2017 15:44:46 +0200 From: Radim =?utf-8?B?S3LEjW3DocWZ?= To: Alexander Graf Cc: Jim Mattson , "Michael S. Tsirkin" , LKML , "Gabriel L. Somlo" , Paolo Bonzini , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , the arch/x86 maintainers , Joerg Roedel , kvm list , linux-doc@vger.kernel.org, qemu-devel@nongnu.org Subject: Re: [PATCH v5 untested] kvm: better MWAIT emulation for guests Message-ID: <20170404134445.GB9525@potion> References: <1489612895-12799-1-git-send-email-mst@redhat.com> <87f187de-64ef-22a2-7714-a811883bce02@suse.de> <20170328142837.GA21738@potion> <20170329121147.GA5129@potion> <20170404123915.GA9525@potion> <20170404131308.GA9826@potion> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 04 Apr 2017 13:44:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1065 Lines: 26 [Cc qemu-devel as we've gone off-topic] 2017-04-04 15:15+0200, Alexander Graf: > On 04/04/2017 03:13 PM, Radim Krčmář wrote: >> 2017-04-04 14:51+0200, Alexander Graf: >> > Please see my patch to force enable CPUID bits ;). >> Nice. MWAIT could also use setting of arbitrary values for its leaf, >> but a generic interface for that would probably look clunky on the >> command line ... > > > I think we should have an interface similar to smbios for that eventually. > Something where you can explicitly set arbitrary CPUID leaf information > using leaf specific syntax. There are more leafs where it would make sense - > cache topology for example. Right, separating cpuid from -cpu makes it bearable, like -cpuid leaf=%x[,subleaf=%x][,eax=%x][,ebx=%x][,ecx=%x][,edx=%x] And Having multiple interfaces for the same thing would result in some corner case decisions ... I think QEMU should check that feature flags specified flags specified by -cpu are not cleared by -cpuid. I'm not sure if setters like "|=" and "&=~" would be beneficial in some cases.