From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andre Przywara Subject: Re: Opteron AMD-V support Date: Fri, 4 Jun 2010 15:47:16 +0200 Message-ID: <4C0903E4.7030404@amd.com> References: <31EF79F027F00341803AA0E9D3EB846D176BA398DC@AUSYD-EXCH3.ap.uis.unisys.com> <201006032147.35712.iggy@theiggy.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Cc: "kvm@vger.kernel.org" To: Brian Jackson , "Govender, Sashan" Return-path: Received: from tx2ehsobe003.messaging.microsoft.com ([65.55.88.13]:30157 "EHLO TX2EHSOBE006.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755655Ab0FDNri (ORCPT ); Fri, 4 Jun 2010 09:47:38 -0400 In-Reply-To: <201006032147.35712.iggy@theiggy.com> Sender: kvm-owner@vger.kernel.org List-ID: Brian Jackson wrote: > On Thursday 03 June 2010 21:33:24 Govender, Sashan wrote: >> Hi >> >> We bumped into this issue with VMWare ESX 4 where it doesn't support >> hardware virtualization if the processor is an AMD Athlon/Opteron >> (http://communities.vmware.com/docs/DOC-9150). Does linux-kvm have a >> similar issue? More specifically will the the module kvm_amd.ko support >> AMD-V on an Opteron 2218? > Yes, KVM doesn't try to be too smart. If you have svm/vt, it runs. If you > don't, it falls back to tcg (qemu's normal/slow mode). The kvm-amd module will > load as long as the bios and the CPU both support and enable svm. That's right. Please note that KVM depends on hardware virtualization, so it does not have the choice like VMware has. Falling back to QEMU/TCG is not comparable to VMware's binary translation, because their approach is highly optimized and limited to x86 on x86, whereas QEMU wants to emulate each supported architecture on each host architecture, so it naturally cannot be as sophisticated as the VMware approach. Nested paging has been supported by KVM for a long time, if it's there it will be automatically used. BTW, every Opteron with a four-digit number supports AMD-V, and KVM will run on every such processor. I am not aware of any _Opteron_ boards not allowing AMD-V, but there are some desktop/notebook systems where the BIOS denies AMD-V (although the processor has it). There presence of the "svm" flag in /proc/cpuinfo is a safe indicator for the usability of KVM. Regards, Andre. -- Andre Przywara AMD-Operating System Research Center (OSRC), Dresden, Germany Tel: +49 351 448-3567-12