From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hollis Blanchard Subject: Re: KVM for Sparc? Date: Tue, 23 Sep 2008 11:07:31 -0500 Message-ID: <1222186051.3545.13.camel@localhost.localdomain> References: <1222114719.3967.43.camel@localhost.localdomain> <90eb1dc70809221331r5350d058k3767a0afc3acd45@mail.gmail.com> <1222118860.3967.61.camel@localhost.localdomain> <20080922.151500.139839534.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: javier@guerrag.com, anthony@codemonkey.ws, blauwirbel@gmail.com, kvm@vger.kernel.org, sparclinux@vger.kernel.org, levon@movementarian.org To: David Miller Return-path: Received: from e4.ny.us.ibm.com ([32.97.182.144]:54872 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751598AbYIWQH6 (ORCPT ); Tue, 23 Sep 2008 12:07:58 -0400 In-Reply-To: <20080922.151500.139839534.davem@davemloft.net> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, 2008-09-22 at 15:15 -0700, David Miller wrote: > From: Hollis Blanchard > Date: Mon, 22 Sep 2008 16:27:40 -0500 > > > On Mon, 2008-09-22 at 15:31 -0500, Javier Guerra wrote: > > > On Mon, Sep 22, 2008 at 3:18 PM, Hollis Blanchard wrote: > > > > It would be even more interesting to implement host support on the Sparc > > > > processors with hardware virtualization support. > > > > > > Does Sparc processors also have 'virtualization support' as an extra > > > feature? i thought that 'non virtualizationability' was an > > > intel-specific limitation. (come on... creating a privileged mode and > > > not trapping violations? who else would design like that?) > > > > Trapping on privileged instructions is enough to get you virtualization > > functionality, but for good performance you really want additional > > hardware support to avoid those traps in the first place. > > That's not really available on sparc. As far as I can see, you have a hypervisor privilege mode which allows your guests to execute privileged instructions like WRPR without trapping. Without that hardware support (with only 2 privilege levels), you'd be forced to run the guest kernel in user mode, trapping on every WRPR (for example). That's what I mean by hardware helping you to avoid traps. -- Hollis Blanchard IBM Linux Technology Center