From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Subject: Re: [PATCH 3/4] vhost: log vring changes
Date: Thu, 3 Dec 2015 10:31:19 +0800
Message-ID: <20151203023119.GX2325@yliu-dev.sh.intel.com>
References: <1449027793-30975-1-git-send-email-yuanhan.liu@linux.intel.com>
 <1449027793-30975-4-git-send-email-yuanhan.liu@linux.intel.com>
 <20151202155405-mutt-send-email-victork@redhat.com>
 <20151202143802.GT2325@yliu-dev.sh.intel.com>
 <20151202170233-mutt-send-email-victork@redhat.com>
 <20151202180824-mutt-send-email-mst@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: dev@dpdk.org, Victor Kaplansky <victork@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mga02.intel.com (mga02.intel.com [134.134.136.20])
 by dpdk.org (Postfix) with ESMTP id 44BDA11C5
 for <dev@dpdk.org>; Thu,  3 Dec 2015 03:27:47 +0100 (CET)
Content-Disposition: inline
In-Reply-To: <20151202180824-mutt-send-email-mst@redhat.com>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Wed, Dec 02, 2015 at 06:26:37PM +0200, Michael S. Tsirkin wrote:
> On Wed, Dec 02, 2015 at 05:58:24PM +0200, Victor Kaplansky wrote:
> > On Wed, Dec 02, 2015 at 10:38:02PM +0800, Yuanhan Liu wrote:
> > > On Wed, Dec 02, 2015 at 04:07:02PM +0200, Victor Kaplansky wrote:
> > > > On Wed, Dec 02, 2015 at 11:43:12AM +0800, Yuanhan Liu wrote:
> > > > > Invoking vhost_log_write() to mark corresponding page as dirty while
> > > > > updating used vring.
> > > > 
> > > > Looks good, thanks!
> > > > 
> > > > I didn't find where you log the dirty pages in result of data
> > > > written to the buffers pointed by the descriptors in RX vring.
> > > > AFAIU, the buffers of RX queue reside in guest's memory and have
> > > > to be marked as dirty if they are written. What do you say?
> > > 
> > > Yeah, we should. I got a question then: why log_guest_addr is set
> > > to the physical address of used vring in guest? I mean, apparently,
> > > we need log more changes other than used vring only.
> > 
> > The physical address of used vring sent to the back-end, since
> > otherwise back-end has to perform virtual to physical
> > translation, and we want to avoid this. The dirty buffers has to
> > be marked as well, but their guest's physical address is known
> > directly from the descriptors.
> 
> Yes, people wanted to be able to do multiple physical
> addresses to one virtual so you do not want to translate
> virt to phys.

Thank you both, it's clear to me then.

	--yliu