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Re: [Qemu-devel] [PATCH 0/2] memory/intel_iommu: Generate error for inco
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [PATCH 0/2] memory/intel_iommu: Generate error for incompatible usage |
Date: |
Tue, 28 Jun 2016 08:49:24 -0600 |
Paolo & Michael,
Any comments on this series? I think we need Paolo's ack for the memory
changes and either of your ack for hw/i386/. I'm happy to pull this
through my tree with your approval though. Thanks,
Alex
On Wed, 15 Jun 2016 09:56:03 -0600
Alex Williamson <address@hidden> wrote:
> VT-d emulation is currently incompatible with device assignment due
> to intel_iommu's lack of support for memory_region_notify_iommu().
> Alexey has proposed a nice addition to the MemoryRegionIOMMUOps
> structure that adds callbacks when the first iommu notifier is
> registered and the last is removed. For POWER this will allow them
> to switch the view of the iommu depending on whether anyone in
> userspace is watching. For VT-d I expect that eventually we'll use
> these callbacks to enable and disable code paths so that we avoid
> notifier overhead when there are no registered notifiy-ees. For now,
> we don't support calling memory_region_notify_iommu(), so this
> signals an incompatible hardware configuration. If we choose to make
> CM=0 a user selectable option, something like this might continue to
> be useful if we only support notifies via invalidations rather than
> full VT-d data structure shadowing.
>
> Even though we're currently working on enabling users like vfio-pci
> with VT-d, I believe this is correct for the current state of things.
> We might even want to consider this stable for v2.6.x so that
> downstreams pick it up to avoid incompatible configurations.
>
> Alexey, I hope I'm not stepping on your toes by extracting this
> from your latest patch series. Please let us know whether you
> approve. Thanks,
>
> Alex
>
> ---
>
> Alex Williamson (1):
> intel_iommu: Throw hw_error on notify_started
>
> Alexey Kardashevskiy (1):
> memory: Add MemoryRegionIOMMUOps.notify_started/stopped callbacks
>
>
> hw/i386/intel_iommu.c | 12 ++++++++++++
> hw/vfio/common.c | 5 +++--
> include/exec/memory.h | 8 +++++++-
> memory.c | 10 +++++++++-
> 4 files changed, 31 insertions(+), 4 deletions(-)