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Date: Thu, 11 Oct 2012 17:48:14 +0200
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [Qemu-devel] [RFC v1 7/7] vhost: abort if an emulated iommu is
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To: "Michael S. Tsirkin" <mst@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 10/11/2012 05:34 PM, Michael S. Tsirkin wrote:
> On Thu, Oct 11, 2012 at 04:35:23PM +0200, Avi Kivity wrote:
>> On 10/11/2012 04:35 PM, Michael S. Tsirkin wrote:
>> 
>> >> No, qemu should configure virtio devices to bypass the iommu, even if it
>> >> is on.
>> > 
>> > Okay so there will be some API that virtio devices should call
>> > to achieve this?
>> 
>> The iommu should probably call pci_device_bypasses_iommu() to check for
>> such devices.
> 
> So maybe this patch should depend on the introduction of such
> an API.

I've dropped it for now.

In fact, virtio/vhost are safe since they use cpu_physical_memory_rw()
and the memory listener watches address_space_memory, no iommu there.
vfio needs to change to listen to pci_dev->bus_master_as, and need
special handling for iommu regions (abort for now, type 2 iommu later).

-- 
error compiling committee.c: too many arguments to function