From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [Qemu-devel] [PATCH v3 5/6] target-i386: Don't enable nested VMX by default Date: Thu, 30 Oct 2014 08:17:58 +0100 Message-ID: <5451E626.1000304@redhat.com> References: <1412365191-22858-1-git-send-email-ehabkost@redhat.com> <1412365191-22858-6-git-send-email-ehabkost@redhat.com> <545126A0.7070802@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Aurelien Jarno , Richard Henderson To: =?ISO-8859-15?Q?Andreas_F=E4rber?= , Eduardo Habkost , qemu-devel@nongnu.org Return-path: Received: from mail-wi0-f177.google.com ([209.85.212.177]:60893 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751426AbaJ3HVQ (ORCPT ); Thu, 30 Oct 2014 03:21:16 -0400 Received: by mail-wi0-f177.google.com with SMTP id ex7so6514295wid.4 for ; Thu, 30 Oct 2014 00:21:14 -0700 (PDT) In-Reply-To: <545126A0.7070802@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: > Here I'm less certain what the best approach is. As you point out, > there's an inconsistency that I agree should be fixed. I wonder however > whether an approach similar to 3/6 for KVM only would be better? I.e., > have VMX as a sometimes-KVM-supported feature be listed in the model and > filter it out for accel=kvm so that -cpu enforce works, but let > accel=tcg fail with features not implemented. This would mean that -cpu coreduo,enforce doesn't work on TCG, but -cpu Nehalem,enforce works. This does not make much sense to me. In fact, I would even omit the x86_cpu_compat_set_features altogether. The inclusion of vmx in these models was a mistake, and nested VMX is not really useful with anything but "-cpu host" because there are too many capabilities communicated via MSRs rather than CPUID. Paolo