From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joerg Roedel <joerg.roedel@amd.com>
Subject: Re: [PATCH 2/5] KVM: SVM: Optimize nested svm msrpm merging
Date: Fri, 26 Feb 2010 14:21:18 +0100
Message-ID: <20100226132118.GF12689@amd.com>
References: <1267118149-15737-1-git-send-email-joerg.roedel@amd.com>
 <1267118149-15737-3-git-send-email-joerg.roedel@amd.com>
 <4B87A248.1050300@redhat.com>
 <20100226122502.GC12689@amd.com>
 <4E7D93ED-E5FC-4A64-B9B0-E2F644CD2B68@suse.de>
 <20100226130401.GD12689@amd.com>
 <4B87C835.4080409@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Cc: Alexander Graf <agraf@suse.de>,
	Marcelo Tosatti <mtosatti@redhat.com>, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org
To: Avi Kivity <avi@redhat.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from va3ehsobe005.messaging.microsoft.com ([216.32.180.15]:22313
	"EHLO VA3EHSOBE005.bigfish.com" rhost-flags-OK-OK-OK-FAIL)
	by vger.kernel.org with ESMTP id S936021Ab0BZNWU (ORCPT
	<rfc822;kvm@vger.kernel.org>); Fri, 26 Feb 2010 08:22:20 -0500
Content-Disposition: inline
In-Reply-To: <4B87C835.4080409@redhat.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Fri, Feb 26, 2010 at 03:10:13PM +0200, Avi Kivity wrote:
> On 02/26/2010 03:04 PM, Joerg Roedel wrote:
> >
> >>I'm still not convinced on this way of doing things. If it's static,
> >>make it static. If it's dynamic, make it dynamic. Dynamically
> >>generating a static list just sounds plain wrong to me.
> >Stop. I had a static list in the first version of the patch. This list
> >was fine except the fact that a developer needs to remember to update
> >this list if the list of non-intercepted msrs is expanded. The whole
> >reason for a dynamically built list is to take the task of maintaining
> >the list away from the developer and remove a possible source of hard to
> >find bugs. This is what the current approach does.
> 
> The problem was the two lists.  If you had a
> 
> static struct svm_direct_access_msrs = {
>     u32 index;
>     bool longmode_only;
> } direct_access_msrs = {
>    ...
> };
> 
> You could generate
> 
> static unsigned *msrpm_offsets_longmode, *msrpm_offsets_legacy;
> 
> as well as the original bitmaps at module init, no?

True for the msrs the guest always has access too. But for the lbr-msrs
the intercept bits may change at runtime. So an addtional flag is
required to indicate if the bits should be cleared initially.

	Joerg