Re: [PATCH 0/5] iommu/virtio: Add identity domains

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 13, 2021 at 01:10:48PM +0100, Jean-Philippe Brucker wrote:
> Support identity domains, allowing to only enable IOMMU protection for a
> subset of endpoints (those assigned to userspace, for example). Users
> may enable identity domains at compile time
> (CONFIG_IOMMU_DEFAULT_PASSTHROUGH), boot time (iommu.passthrough=1) or
> runtime (/sys/kernel/iommu_groups/*/type = identity).


I put this in my branch so it can get testing under linux-next,
but pls notice if the ballot does not conclude in time
for the merge window I won't send it to Linus.

> Patches 1-2 support identity domains using the optional
> VIRTIO_IOMMU_F_BYPASS_CONFIG feature. The feature bit is not yet in the
> spec, see [1] for the latest proposal.
> 
> Patches 3-5 add a fallback to identity mappings, when the feature is not
> supported.
> 
> Note that this series doesn't touch the global bypass bit added by
> VIRTIO_IOMMU_F_BYPASS_CONFIG. All endpoints managed by the IOMMU should
> be attached to a domain, so global bypass isn't in use after endpoints
> are probed. Before that, the global bypass policy is decided by the
> hypervisor and firmware. So I don't think Linux needs to touch the
> global bypass bit, but there are some patches available on my
> virtio-iommu/bypass branch [2] to test it.
> 
> QEMU patches are on my virtio-iommu/bypass branch [3] (and the list)
> 
> [1] https://www.mail-archive.com/virtio-dev@lists.oasis-open.org/msg07898.html
> [2] https://jpbrucker.net/git/linux/log/?h=virtio-iommu/bypass
> [3] https://jpbrucker.net/git/qemu/log/?h=virtio-iommu/bypass
> 
> Jean-Philippe Brucker (5):
>   iommu/virtio: Add definitions for VIRTIO_IOMMU_F_BYPASS_CONFIG
>   iommu/virtio: Support bypass domains
>   iommu/virtio: Sort reserved regions
>   iommu/virtio: Pass end address to viommu_add_mapping()
>   iommu/virtio: Support identity-mapped domains
> 
>  include/uapi/linux/virtio_iommu.h |   8 ++-
>  drivers/iommu/virtio-iommu.c      | 113 +++++++++++++++++++++++++-----
>  2 files changed, 101 insertions(+), 20 deletions(-)
> 
> -- 
> 2.33.0

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