From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46826) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fIqxf-0002A0-4i for qemu-devel@nongnu.org; Wed, 16 May 2018 03:35:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fIqxc-0000Y1-1x for qemu-devel@nongnu.org; Wed, 16 May 2018 03:34:59 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:51530 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fIqxb-0000Xn-Sc for qemu-devel@nongnu.org; Wed, 16 May 2018 03:34:55 -0400 References: <1526384258-3581-1-git-send-email-lpetrut@cloudbasesolutions.com> <9ED401B4-3DF6-4BC8-9D38-14C78C9D1A66@cloudbasesolutions.com> From: Paolo Bonzini Message-ID: Date: Wed, 16 May 2018 09:34:52 +0200 MIME-Version: 1.0 In-Reply-To: <9ED401B4-3DF6-4BC8-9D38-14C78C9D1A66@cloudbasesolutions.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] WHPX Add signature CPUID List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alessandro Pilotti Cc: "petrutlucian94@gmail.com" , Lucian Petrut , Eduardo Habkost , "open list:All patches CC here" , Justin Terry , Richard Henderson On 16/05/2018 01:55, Alessandro Pilotti wrote: > Hi Paolo, > > The main reason for different signatures is to allow guest workloads > to be aware of the differences between the two platforms (eg VirtIO > vs VMBus). Why does it matter? CPUID tells you about the enlightenments that the hypervisor provides, not the availability of the VMBus. VMBus requires some of the enlightenments, mostly related to the synthetic interrupt controllers, but the opposite is not true---you can have enlightenments without VMBus, and in fact you probably want WHPX to enable the relaxed timing enlightenment. Thanks, Paolo