Re: [Qemu-devel] [PATCH v1 0/3] intel_iommu: support scalable mode

[Peter Xu <peterx@redhat.com>]

On Tue, Mar 05, 2019 at 10:34:52AM +0800, Yi Sun wrote:
> Intel vt-d rev3.0 [1] introduces a new translation mode called
> 'scalable mode', which enables PASID-granular translations for
> first level, second level, nested and pass-through modes. The
> vt-d scalable mode is the key ingredient to enable Scalable I/O
> Virtualization (Scalable IOV) [2] [3], which allows sharing a
> device in minimal possible granularity (ADI - Assignable Device
> Interface). As a result, previous Extended Context (ECS) mode
> is deprecated (no production ever implements ECS).
> 
> This patch set emulates a minimal capability set of VT-d scalable
> mode, equivalent to what is available in VT-d legacy mode today:
>     1. Scalable mode root entry, context entry and PASID table
>     2. Seconds level translation under scalable mode
>     3. Queued invalidation (with 256 bits descriptor)
>     4. Pass-through mode
> 
> Corresponding intel-iommu driver support will be included in
> kernel 5.0:
>     https://www.spinics.net/lists/kernel/msg2985279.html
> 
> We will add emulation of full scalable mode capability along with
> guest iommu driver progress later, e.g.:
>     1. First level translation
>     2. Nested translation
>     3. Per-PASID invalidation descriptors
>     4. Page request services for handling recoverable faults
> 
> To verify the patches, below cases were tested according to Peter Xu's
> suggestions.
>     +---------+----------------------------------------------------------------+----------------------------------------------------------------+
>     |         |                      w/ Device Passthr                         |                     w/o Device Passthr                         |
>     |         +-------------------------------+--------------------------------+-------------------------------+--------------------------------+
>     |         | virtio-net-pci, vhost=on      | virtio-net-pci, vhost=off      | virtio-net-pci, vhost=on      | virtio-net-pci, vhost=off      |
>     |         +-------------------------------+--------------------------------+-------------------------------+--------------------------------+
>     |         | netperf | kernel bld | data cp| netperf | kernel bld | data cp | netperf | kernel bld | data cp| netperf | kernel bld | data cp |
>     +---------+-------------------------------+--------------------------------+-------------------------------+--------------------------------+
>     | Legacy  | Pass    | Pass       | Pass   | Pass    | Pass       | Pass    | Pass    | Pass       | Pass   | Pass    | Pass       | Pass    |
>     +---------+-------------------------------+--------------------------------+-------------------------------+--------------------------------+
>     | Scalable| Pass    | Pass       | Pass   | Pass    | Pass       | Pass    | Pass    | Pass       | Pass   | Pass    | Pass       | Pass    |
>     +---------+-------------------------------+--------------------------------+-------------------------------+--------------------------------+

Legacy vfio-pci?

I've reviewed the whole series, I would assume that the maintainer
might still test it a bit before a pull but again even before that I
would really like to double confirm this series won't break anything.

Thanks,

-- 
Peter Xu