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Date: Thu, 11 Oct 2012 15:31:55 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20121011133155.GA8983@redhat.com>
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Subject: Re: [Qemu-devel] [RFC v1 7/7] vhost: abort if an emulated iommu is
	used
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To: Avi Kivity <avi@redhat.com>
Cc: qemu-devel@nongnu.org, liu ping fan <qemulist@gmail.com>, Blue Swirl <blauwirbel@gmail.com>, Alex Williamson <alex.williamson@redhat.com>, Anthony Liguori <anthony@codemonkey.ws>, Paolo Bonzini <pbonzini@redhat.com>

On Thu, Oct 11, 2012 at 03:27:03PM +0200, Avi Kivity wrote:
> vhost doesn't support guest iommus yet, indicate it to the user
> by gently depositing a core on their disk.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>

Actually there is no problem. virtio bypasses an IOMMU,
so vhost works fine by writing into guest memory directly.

So I don't think we need this patch.

> ---
>  hw/vhost.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/hw/vhost.c b/hw/vhost.c
> index 0b4ac3f..cd5d9f5 100644
> --- a/hw/vhost.c
> +++ b/hw/vhost.c
> @@ -451,6 +451,8 @@ static void vhost_region_add(MemoryListener *listener,
>      struct vhost_dev *dev = container_of(listener, struct vhost_dev,
>                                           memory_listener);
>  
> +    assert(!memory_region_is_iommu(section.mr));
> +
>      if (!vhost_section(section)) {
>          return;
>      }
> -- 
> 1.7.12