Re: [PATCH v1 0/5] virtio: Add the virtio-msg transport

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

On Tue, Oct 28, 2025 at 04:23:45PM +0100, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias@amd.com>
> 
> This adds virtio-msg, a new virtio transport. Virtio-msg works by
> exchanging messages over a bus and doesn't rely on trapping and emulation
> making it a good fit for a number of applications such as AMP, real-time
> and safety applications.
> 
> Together with the new transport, this series adds a PCI device that
> implements an AMP setup much like it could look if two SoC's would
> use virtio-msg across a PCI link.
> 
> Current gaps and limitations:
> Shared memory FIFO layout likely to change in the future.
> Temporarily uses PCI Vendor Xilinx / Device 0x9039.
> Documentation.


I'm happy that the spec effort is making progress finally.
Do you want to repost a version aligned to the latest spec posted?


> The virtio-msg draft spec:
> https://github.com/Linaro/virtio-msg-spec/
> 
> QEMU with these patches:
> https://github.com/edgarigl/qemu/tree/edgar/virtio-msg-rfc
> 
> Linux with virtio-msg support:
> https://github.com/edgarigl/linux/tree/edgari/virtio-msg-6.17
> 
> To try it, first build Linux with the following enabled:
> CONFIG_VIRTIO_MSG=y
> CONFIG_VIRTIO_MSG_AMP=y
> CONFIG_VIRTIO_MSG_AMP_PCI=y
> 
> Boot linux on QEMU with a virtio-msg-amp-pci device, in this example
> with a virtio-net device attached to it:
> 
>  -device virtio-msg-amp-pci
>  -device virtio-net-device,netdev=n0
>  -netdev user,id=n0
> 
> If you're running on a QEMU machine that has virtio-mmio enabled, e.g 
> ARM virt, you'll need to specify the virtio-bus for the device, otherwise
> QEMU will connect it to virtio-mmio. For ARM virt machines:
> 
>  -device virtio-msg-amp-pci
>  -device virtio-net-device,netdev=n0,bus=/gpex-pcihost/pcie.0/virtio-msg-amp-pci/fifo0/virtio-msg/bus0/virtio-msg-dev
>  -netdev user,id=n0
> 
> Cheers,
> Edgar
> 
> Edgar E. Iglesias (5):
>   virtio: Introduce notify_queue
>   virtio: Add virtio_queue_get_rings
>   virtio: Add the virtio-msg transport
>   hw/misc: Add generic virtio-msg AMP PCI device
>   docs: Describe virtio-msg-amp-pci
> 
>  .../devices/virtio/virtio-msg-amp-pci.rst     |  70 ++
>  hw/misc/Kconfig                               |   7 +
>  hw/misc/meson.build                           |   1 +
>  hw/misc/virtio-msg-amp-pci.c                  | 328 +++++++
>  hw/virtio/Kconfig                             |   4 +
>  hw/virtio/meson.build                         |   5 +
>  hw/virtio/virtio-msg-bus.c                    |  89 ++
>  hw/virtio/virtio-msg.c                        | 695 ++++++++++++++
>  hw/virtio/virtio.c                            |  23 +
>  include/hw/virtio/spsc_queue.h                | 213 +++++
>  include/hw/virtio/virtio-bus.h                |   1 +
>  include/hw/virtio/virtio-msg-bus.h            |  95 ++
>  include/hw/virtio/virtio-msg-prot.h           | 846 ++++++++++++++++++
>  include/hw/virtio/virtio-msg.h                |  56 ++
>  include/hw/virtio/virtio.h                    |   2 +
>  15 files changed, 2435 insertions(+)
>  create mode 100644 docs/system/devices/virtio/virtio-msg-amp-pci.rst
>  create mode 100644 hw/misc/virtio-msg-amp-pci.c
>  create mode 100644 hw/virtio/virtio-msg-bus.c
>  create mode 100644 hw/virtio/virtio-msg.c
>  create mode 100644 include/hw/virtio/spsc_queue.h
>  create mode 100644 include/hw/virtio/virtio-msg-bus.h
>  create mode 100644 include/hw/virtio/virtio-msg-prot.h
>  create mode 100644 include/hw/virtio/virtio-msg.h
> 
> -- 
> 2.43.0