From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: QEMU PIC indirection patch for in-kernel APIC work Date: Wed, 04 Apr 2007 10:53:18 -0500 Message-ID: <4613C9EE.5030600@codemonkey.ws> References: <4613BF07.50606@qumranet.com> <8FFF7E42E93CC646B632AB40643802A8025B9580@scsmsx412.amr.corp.intel.com> <64F9B87B6B770947A9F8391472E032160B318E96@ehost011-8.exch011.intermedia.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Avi Kivity To: Dor Laor Return-path: In-Reply-To: <64F9B87B6B770947A9F8391472E032160B318E96-yEcIvxbTEBqsx+V+t5oei8rau4O3wl8o3fe8/T/H7NteoWH0uzbU5w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Dor Laor wrote: >>>> This is for the TPR right? VT has special logic to handle TPR >>>> virtualization doesn't it? I thought SVM did too... >>>> >>>> >>> Yes, the TPR. Both VT and SVM virtualize CR8 in 64-bit mode. SVM >>> also supports CR8 in 32-bit mode through a nwe instruction encoding, >>> but >>> nobody uses that to my knowledge. Maybe some brave soul can hack kvm >>> to patch the new instruction in place of the mmio instruction Windows >>> uses >>> to bang on the tpr. >>> >> Actually VT has virtual TPR support that does not require CR8. We >> submitted a patch for Xen. Please see >> http://lists.xensource.com/archives/html/xen-devel/2007-03/msg00993.htm >> > l > >> The spec should be available soon. We are working on a patch for KVM. >> >> Jun >> > > That's superb! Windows gives us really bad time with all of those TPR > accesses. Because of that we currently prefer of using the non-acpi HAL. > > On what version on chip is this feature supported? > > This pushes towards in kernel apic too. Can't see how we avoid it. > Does it really? IIUC, we would avoid TPR traps entirely and would just need to synchronize the TPR whenever we go down to userspace. Regards, Anthony Liguori ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV