Linux Virtualization - Sep 2020 - [PATCH v3 0/6] Add virtio-iommu built-in topology

On Fri, Sep 04, 2020 at 06:24:12PM +0200, Auger Eric
wrote:
> Hi,
> 
> On 8/21/20 3:15 PM, Jean-Philippe Brucker wrote:
> > Add a topology description to the virtio-iommu driver and enable x86
> > platforms.
> > 
> > Since [v2] we have made some progress on adding ACPI support for
> > virtio-iommu, which is the preferred boot method on x86. It will be a
> > new vendor-agnostic table describing para-virtual topologies in a
> > minimal format. However some platforms don't use either ACPI or DT
for
> > booting (for example microvm), and will need the alternative topology
> > description method proposed here. In addition, since the process to
get
> > a new ACPI table will take a long time, this provides a boot method
even
> > to ACPI-based platforms, if only temporarily for testing and
> > development.
> > 
> > v3:
> > * Add patch 1 that moves virtio-iommu to a subfolder.
> > * Split the rest:
> >   * Patch 2 adds topology-helper.c, which will be shared with the ACPI
> >     support.
> >   * Patch 4 adds definitions.
> >   * Patch 5 adds parser in topology.c.
> > * Address other comments.
> > 
> > Linux and QEMU patches available at:
> > https://jpbrucker.net/git/linux virtio-iommu/devel
> > https://jpbrucker.net/git/qemu virtio-iommu/devel
> I have tested that series with above QEMU branch on ARM with virtio-net
> and virtio-blk translated devices in non DT mode.
> 
> It works for me:
> Tested-by: Eric Auger <eric.auger at redhat.com>
> 
> Thanks
> 
> Eric
OK so this looks good. Can you pls repost with the minor tweak
suggested and all acks included, and I will queue this?

Thanks!
> > 
> > [spec]
https://lists.oasis-open.org/archives/virtio-dev/202008/msg00067.html
> > [v2]
https://lore.kernel.org/linux-iommu/20200228172537.377327-1-jean-philippe at
linaro.org/
> > [v1]
https://lore.kernel.org/linux-iommu/20200214160413.1475396-1-jean-philippe at
linaro.org/
> > [rfc]
https://lore.kernel.org/linux-iommu/20191122105000.800410-1-jean-philippe at
linaro.org/
> > 
> > Jean-Philippe Brucker (6):
> >   iommu/virtio: Move to drivers/iommu/virtio/
> >   iommu/virtio: Add topology helpers
> >   PCI: Add DMA configuration for virtual platforms
> >   iommu/virtio: Add topology definitions
> >   iommu/virtio: Support topology description in config space
> >   iommu/virtio: Enable x86 support
> > 
> >  drivers/iommu/Kconfig                     |  18 +-
> >  drivers/iommu/Makefile                    |   3 +-
> >  drivers/iommu/virtio/Makefile             |   4 +
> >  drivers/iommu/virtio/topology-helpers.h   |  50 +++++
> >  include/linux/virt_iommu.h                |  15 ++
> >  include/uapi/linux/virtio_iommu.h         |  44 ++++
> >  drivers/iommu/virtio/topology-helpers.c   | 196 ++++++++++++++++
> >  drivers/iommu/virtio/topology.c           | 259
++++++++++++++++++++++
> >  drivers/iommu/{ => virtio}/virtio-iommu.c |   4 +
> >  drivers/pci/pci-driver.c                  |   5 +
> >  MAINTAINERS                               |   3 +-
> >  11 files changed, 597 insertions(+), 4 deletions(-)
> >  create mode 100644 drivers/iommu/virtio/Makefile
> >  create mode 100644 drivers/iommu/virtio/topology-helpers.h
> >  create mode 100644 include/linux/virt_iommu.h
> >  create mode 100644 drivers/iommu/virtio/topology-helpers.c
> >  create mode 100644 drivers/iommu/virtio/topology.c
> >  rename drivers/iommu/{ => virtio}/virtio-iommu.c (99%)
> >

On Thu, Sep 24, 2020 at 05:00:35AM -0400, Michael S. Tsirkin
wrote:
> OK so this looks good. Can you pls repost with the minor tweak
> suggested and all acks included, and I will queue this?
My NACK still stands, as long as a few questions are open:

	1) The format used here will be the same as in the ACPI table? I
	   think the answer to this questions must be Yes, so this leads
	   to the real question:
	   
	2) Has the ACPI table format stabalized already? If and only if
	   the answer is Yes I will Ack these patches. We don't need to
	   wait until the ACPI table format is published in a
	   specification update, but at least some certainty that it
	   will not change in incompatible ways anymore is needed.

So what progress has been made with the ACPI table specification, is it
just a matter of time to get it approved or are there concerns?

Regards,

	Joerg

On Thu, Sep 24, 2020 at 11:21:29AM +0200, Joerg Roedel
wrote:
> On Thu, Sep 24, 2020 at 05:00:35AM -0400, Michael S. Tsirkin wrote:
> > OK so this looks good. Can you pls repost with the minor tweak
> > suggested and all acks included, and I will queue this?
> 
> My NACK still stands, as long as a few questions are open:
> 
> 	1) The format used here will be the same as in the ACPI table? I
> 	   think the answer to this questions must be Yes, so this leads
> 	   to the real question:
I am not sure it's a must.
We can always tweak the parser if there are slight differences
between ACPI and virtio formats.

But we do want the virtio format used here to be approved by the virtio
TC, so it won't change.

Eric, Jean-Philippe, does one of you intend to create a github issue
and request a ballot for the TC? It's been posted end of August with no
changes ...
> 	2) Has the ACPI table format stabalized already? If and only if
> 	   the answer is Yes I will Ack these patches. We don't need to
> 	   wait until the ACPI table format is published in a
> 	   specification update, but at least some certainty that it
> 	   will not change in incompatible ways anymore is needed.
> 
Not that I know, but I don't see why it's a must.
> So what progress has been made with the ACPI table specification, is it
> just a matter of time to get it approved or are there concerns?
> 
> Regards,
> 
> 	Joerg