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Re: [Qemu-devel] [PATCH v3 3/3] IOMMU: Integrate between VFIO and vIOMMU
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From: |
Alex Williamson |
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Subject: |
Re: [Qemu-devel] [PATCH v3 3/3] IOMMU: Integrate between VFIO and vIOMMU to support device assignment |
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Date: |
Thu, 2 Jun 2016 07:34:17 -0600 |
On Thu, 02 Jun 2016 13:09:27 +0000
"Aviv B.D." <address@hidden> wrote:
> Hi,
>
> In case of hot plug vfio device there should not be any active mapping
> to this device prior the device addition.
Counter example - a device is hot added to a guest booted with iommu=pt.
> Also before it added to a guest
> the guest should not attach the device to any domain as the device is not
> present.
The static identity map domain (ie. passthrough domain) can precede the
device existing.
> With CM enabled the guest must invalidate the domain or individual mappings
> that belong to this new device before any use of those maps.
>
> I'm still not sure that this functionality is necessary in x86 and
> currently there
> is a scenario (for x86) that use this functionality.
Clearly I disagree, it is necessary. Thanks,
Alex