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Resolve VIRTIO-154: Document VIRTIO_F_IOMMU_PLATFORM reserved feature bit (33)

Should the TC accept changes listed in the description to resolve issue VIRTIO-154, for inclusion in specification version(s) "virtio 1.1 cs01", and future versions of the specification?

Please vote Yes if you agree with all of the following.
If you disagree, please vote No.
If you don't have an opinion, please vote Abstain.

I move that:
The TC agrees to resolve the following specification issue:
VIRTIO-154: Document VIRTIO_F_IOMMU_PLATFORM reserved feature bit (33)
On most virtio systems, physical addresses are provided from the driver
to the device and subsequently used to access memory directly. However,
some systems feature an IOMMU that complicates things slightly:

- The IOMMU might require configuration for DMA to work at all. Once
configured, the driver must pass bus addresses to the device, which
are then translated by the IOMMU into physical addresses in memory.

- The IOMMU might be bypassed by virtio DMA. In this case, physical
addresses must still be provided to the device by the driver, even
though an IOMMU appears to be present.

This has been solved by the addition of a new reserved feature bit,
VIRTIO_F_IOMMU_PLATFORM, to describe the two cases above. Legacy systems
will not negotiate the feature, and therefore continue to operate
directly on physical addresses.


The TC accepts the following proposed changes to the specification:
Document VIRTIO_F_IOMMU_PLATFORM that's already
in use by Linux guests.

See message:
Date: Thu, 20 Oct 2016 18:20:01 +0100
From: Will Deacon
To: virtio-dev@lists.oasis-open.org
Cc: Will Deacon , "Michael S. Tsirkin" , Stefan Hajnoczi
Subject: [PATCH v2] context: Document VIRTIO_F_IOMMU_PLATFORM reserved feature bit (33)



The TC agrees to include the above change(s) in specification version(s) "virtio 1.1 cs01", and future versions of the


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 [ ]  Yes
 [ ]  No
 [ ]  Abstain
Opening:   Thursday, 10 November 2016 @ 11:45 am EST
Closing:   Thursday, 17 November 2016 @ 11:45 am EST
Group:   OASIS Virtual I/O Device (VIRTIO) TC
Ballot has closed.

Referenced Items
Name Type Date Action

Voting Details

Voting Summary

Options with highest number of votes are bold

Option # Votes % of Total
Yes 6 100%
No 0 0%
Abstain 0
Eligible members who have voted: 6 of 7 86%
Eligible members who have abstained: 0 of 7 0%
Eligible members who have not voted: 1 of 7 14%

Voting Details

Voter Company VoteReference Document and/or Comment
Cornelia Huck
Daniel Kiper
Den Lunev
Parallels IP Holdings GmbH
Amit Shah
Red Hat
Michael S. Tsirkin
Red Hat
Stefan Hajnoczi
Red Hat
Jan Kiszka
Siemens AG