From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH RFC v1 2/2] hyper-v: initialize Hyper-V CPUID leafs. Date: Mon, 17 Oct 2011 12:42:39 +0200 Message-ID: <4E9C069F.209@redhat.com> References: <1318843022-20344-1-git-send-email-vrozenfe@redhat.com> <1318843022-20344-3-git-send-email-vrozenfe@redhat.com> <4E9BF816.3010205@redhat.com> <4E9C0641.4080107@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: qemu-devel , "kvm@vger.kernel.org" To: Avi Kivity Return-path: In-Reply-To: <4E9C0641.4080107@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org On 10/17/2011 12:41 PM, Avi Kivity wrote: > > Even not counting that hyper-v support should IMHO not be in > > KVM-specific code, I still think this shouldn't remove KVM leaves > > completely but rather move them to 0x40000100. The KVM > > paravirtualization code then can similarly probe with 0x100 stride up > > to 0x40001000. This is what was done for Xen, and it allows to enable > > enlightenments independent of whether the guest is Linux or Windows. > > > > However, let's get a third opinion---Avi, what do you think? > > I agree with you, especially as this already works for Xen. > > Note it doesn't completely solve the issue (so we have two interfaces, > which is the preferred one?), but it's better than nothing. Windows doesn't look beyond 0x40000000, so Hyper-V stays there and KVM has to shift. So MS solved that part for us. :) Paolo From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:38480) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RFkea-0002Oe-Iy for qemu-devel@nongnu.org; Mon, 17 Oct 2011 06:42:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RFkeZ-0002nR-3k for qemu-devel@nongnu.org; Mon, 17 Oct 2011 06:42:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:64075) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RFkeY-0002nJ-N1 for qemu-devel@nongnu.org; Mon, 17 Oct 2011 06:42:43 -0400 Message-ID: <4E9C069F.209@redhat.com> Date: Mon, 17 Oct 2011 12:42:39 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1318843022-20344-1-git-send-email-vrozenfe@redhat.com> <1318843022-20344-3-git-send-email-vrozenfe@redhat.com> <4E9BF816.3010205@redhat.com> <4E9C0641.4080107@redhat.com> In-Reply-To: <4E9C0641.4080107@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH RFC v1 2/2] hyper-v: initialize Hyper-V CPUID leafs. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: qemu-devel , "kvm@vger.kernel.org" On 10/17/2011 12:41 PM, Avi Kivity wrote: > > Even not counting that hyper-v support should IMHO not be in > > KVM-specific code, I still think this shouldn't remove KVM leaves > > completely but rather move them to 0x40000100. The KVM > > paravirtualization code then can similarly probe with 0x100 stride up > > to 0x40001000. This is what was done for Xen, and it allows to enable > > enlightenments independent of whether the guest is Linux or Windows. > > > > However, let's get a third opinion---Avi, what do you think? > > I agree with you, especially as this already works for Xen. > > Note it doesn't completely solve the issue (so we have two interfaces, > which is the preferred one?), but it's better than nothing. Windows doesn't look beyond 0x40000000, so Hyper-V stays there and KVM has to shift. So MS solved that part for us. :) Paolo