From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: KVM call minutes for Sept 21 Date: Sun, 26 Sep 2010 22:25:54 +0200 Message-ID: <20100926202554.GN15338@8bytes.org> References: <20100921180506.GI28009@x200.localdomain> <20100922000438.GA2844@fermat.math.technion.ac.il> <20100922090248.GD11145@redhat.com> <20100922162900.GA12492@fermat.math.technion.ac.il> <20100922174706.GA18005@redhat.com> <20100922192038.GK15338@8bytes.org> <4C9F52A1.1060306@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Gleb Natapov , Nadav Har'El , Chris Wright , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from 8bytes.org ([88.198.83.132]:36822 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753593Ab0IZUZ4 (ORCPT ); Sun, 26 Sep 2010 16:25:56 -0400 Content-Disposition: inline In-Reply-To: <4C9F52A1.1060306@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Sun, Sep 26, 2010 at 04:03:13PM +0200, Avi Kivity wrote: > I don't expect drastic changes, but then, I still don't understand it well. > > Part of the review process is the maintainer becoming familiar (and, in > some cases, comfortable) with the code. The nit-picking is often just > me proving to myself that I understand what's happening. Right, understanding is an important part. One thing I try to achieve for nested-svm is to make it less likely that unrelated code changes break it. One step will be accessor funtions to change intercept masks and tsc_offset. > btw, speaking of drastic changes to nsvm, one thing I'd like to see is > the replacement of those kmaps with something like put_user_try() and > put_user_catch(). It should be as fast (or faster) than kmaps, and not > affect preemptibility. Yes, I want to get rid of them too. I thought about using copy_from/to_user in the vmrun/vmexit path. I need to measure if this has any performance impact, though. But the vmrun/vmexit path in nested-svm will see some major changes in the near future anyway to improve performance and prepare it for clean-bits emulation. In this step I will also address the kmap problem. But first on the list for me is to make the instruction emulator aware of instruction intercepts. Security is more important then performance. Joerg