From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: Linux with kvm-intel locks up VMplayer guest is started Date: Tue, 17 Jun 2008 13:09:39 -0500 Message-ID: <4857FDE3.8050602@codemonkey.ws> References: <20080616150550.GA16086@deprecation.cyrius.com> <48568503.90607@codemonkey.ws> <20080617123918.GA2397@deprecation.cyrius.com> <4857B92F.9020309@codemonkey.ws> <20080617133234.GE2397@deprecation.cyrius.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Martin Michlmayr Return-path: Received: from yx-out-2324.google.com ([74.125.44.29]:47024 "EHLO yx-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755327AbYFQSKA (ORCPT ); Tue, 17 Jun 2008 14:10:00 -0400 Received: by yx-out-2324.google.com with SMTP id 31so562459yxl.1 for ; Tue, 17 Jun 2008 11:09:59 -0700 (PDT) In-Reply-To: <20080617133234.GE2397@deprecation.cyrius.com> Sender: kvm-owner@vger.kernel.org List-ID: Martin Michlmayr wrote: > * Anthony Liguori [2008-06-17 08:16]: > >> VMware is a binary kernel module that's out of kernel. KVM is not >> misbehaving and the fact that VMware breaks when the KVM module is >> loaded isn't our problem. If they submitted their code for >> inclusion in mainline, we could possibly come up with solution for >> arbitrating who is using VT. >> > > I feared I'd get a response like this. But unless this is a known > issue in VMware (which I don't think it is), you don't know whether > it's not a bug in kvm-intel. > We know exactly what the problem is. KVM activates VT unconditionally. There's no hardware mechanism to arbitrate access to VT. KVM is the only thing in the Linux kernel that uses VT so we don't have a software mechanism to arbitrate access to VT. If the VMware code was upstream, then we could work together to make a software arbitration mechanism. It's not, and worse yet, it's closed source so there's no chance it will be. Even if someone wrote an arbitration mechanism and got VMware to use it, it still shouldn't be merged because KVM would be the only thing using that mechanism upstream. I'm not interested in adding kernel infrastructure to support external binary kernel modules. Regards, Anthony Liguori