From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Subject: Re: [PATCH] Activate Virtualization On Demand v2 Date: Wed, 05 Nov 2008 12:01:04 +0100 Message-ID: <49117CF0.6000400@suse.de> References: <1225874896-13186-1-git-send-email-agraf@suse.de> <20081105105812.GC25523@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, avi@redhat.com, kraxel@redhat.com, anthony@codemonkey.ws, Sander.Vanleeuwen@sun.com, zach@vmware.com, brogers@novell.com To: "Daniel P. Berrange" Return-path: Received: from ns1.suse.de ([195.135.220.2]:33048 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754420AbYKELBG (ORCPT ); Wed, 5 Nov 2008 06:01:06 -0500 In-Reply-To: <20081105105812.GC25523@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Daniel P. Berrange wrote: > On Wed, Nov 05, 2008 at 09:48:16AM +0100, Alexander Graf wrote: > >> X86 CPUs need to have some magic happening to enable the virtualization >> extensions on them. This magic can result in unpleasant results for >> users, like blocking other VMMs from working (vmx) or using invalid TLB >> entries (svm). >> >> Currently KVM activates virtualization when the respective kernel module >> is loaded. This blocks us from autoloading KVM modules without breaking >> other VMMs. >> >> To circumvent this problem at least a bit, this patch introduces on >> demand activation of virtualization. This means, that instead >> virtualization is enabled on creation of the first virtual machine >> and disabled on removal of the last one. >> > > Pardon my unfamiliarity with the code, but with this change applied, > will we still get an explicit error at time of loading kvm-intel.ko > if VMX were disabled in the BIOS ? Or will that error reporting be > pushed off to time when VMX is first activated ? > The BIOS and hardware support checks are in kvm_arch_init, which is still called at load-time of the module. Alex