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[PATCH 0/2] spapr: Use vIOMMU translation for virtio by default

From: David Gibson
Subject: [PATCH 0/2] spapr: Use vIOMMU translation for virtio by default
Date: Fri, 7 Feb 2020 15:30:53 +1100

Upcoming Secure VM support for pSeries machines introduces some
complications for virtio, since the transfer buffers need to be
explicitly shared so that the hypervisor can access them.

While it's not strictly speaking dependent on it, the fact that virtio
devices bypass normal platform IOMMU translation complicates the issue
on the guest side.  Since there are some significan downsides to
bypassing the vIOMMU anyway, let's just disable that.

There's already a flag to do this in virtio, just turn it on by
default for forthcoming pseries machine types.

The implementation does this with a compat_props_add() from the latest
machine type.  This breaks the previous convention that the setup for
the latest machine type didn't do anything, instead just taking all
the defaults from the abstract base class.  However,
compat_props_add() can't be used from the base class, because
mc->compat_props is explicitly uninitialized for abstract classes.  If
anyone knows a better way to handle this, let me know.

David Gibson (2):
  spapr: Disable legacy virtio devices for pseries-5.0 and later
  spapr: Enable virtio iommu_platform=on by default

 hw/ppc/spapr.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)


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