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From: Jason Wang <jasowang@redhat.com>
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Date: Wed, 5 Dec 2018 09:30:19 +0800
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Subject: Re: [Qemu-devel] Logging dirty pages from vhost-net in-kernel with
 vIOMMU
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To: Jintack Lim <jintack@cs.columbia.edu>, QEMU Devel Mailing List <qemu-devel@nongnu.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>


On 2018/12/5 =E4=B8=8A=E5=8D=882:37, Jintack Lim wrote:
> Hi,
>
> I'm wondering how the current implementation works when logging dirty
> pages during migration from vhost-net (in kernel) when used vIOMMU.
>
> I understand how vhost-net logs GPAs when not using vIOMMU. But when
> we use vhost with vIOMMU, then shouldn't vhost-net need to log the
> translated address (GPA) instead of the address written in the
> descriptor (IOVA) ? The current implementation looks like vhost-net
> just logs IOVA without translation in vhost_get_vq_desc() in
> drivers/vhost/net.c. It seems like QEMU doesn't do any further
> translation of the dirty log when syncing.
>
> I might be missing something. Could somebody shed some light on this?


Good catch. It looks like a bug to me. Want to post a patch for this?

Thanks


>
> Thanks,
> Jintack
>
>