Re: [PATCH v5 0/5] VIRTIO-IOMMU probe request support and MSI bypass on ARM

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

On Wed, Jun 24, 2020 at 03:26:20PM +0200, Eric Auger wrote:
> By default the virtio-iommu translates MSI transactions. This
> behavior is inherited from ARM SMMU. However the virt machine
> code knows where the MSI doorbells are, so we can easily
> declare those regions as VIRTIO_IOMMU_RESV_MEM_T_MSI. With that
> setting the guest iommu subsystem will not need to map MSIs.
> This setup will simplify the VFIO integration.
> 
> In this series, the ITS or GICV2M doorbells are declared as
> HW MSI regions to be bypassed by the VIRTIO-IOMMU.


> This also paves the way to the x86 integration where the MSI
> region, [0xFEE00000,0xFEEFFFFF], will be exposed by the q35
> machine.  However this will be handled in a separate series
> when not-DT support gets resolved.

What's going on with that btw?
I think the next step is to put the spec up for virtio tc vote,
then we can merge that, right? acpi parts will need to be
ratified by the acpi sig.

> Best Regards
> 
> Eric
> 
> This series can be found at:
> https://github.com/eauger/qemu/tree/v5.0.0-virtio-iommu-msi-bypass-v5
> 
> History:
> 
> v4 -> v5:
> - Take into account some additional comments from Markus:
>   - reserved region type becomes an unsigned + some comment/desc
>     rewording
>   - assert if the type is not RESERVED or MSI
> 
> v3 -> v4:
> - collected Jean and markus's R-bs
> - tool into account all Markus' comments in [1/5] (except removal of
>   goto)
> - use ':' as delimitor instead of commas
> - add example in 4/5 commit message as suggested by Markus
> 
> v2 -> v3:
> - Introduce VIRT_MSI_CTRL_NONE in VirtMSIControllerType
> - do not fill the remainder of the probe buffer
> 
> v1 -> v2:
> - check which MSI controller is in use and advertise the
>   corresponding MSI doorbell
> - managed for both ITS and GICv2M
> - various fixes spotted by Peter and Jean-Philippe, see
>   individual logs
> 
> v1: Most of those patches were respinned from
>   [PATCH for-5.0 v11 00/20] VIRTIO-IOMMU device
>   except the last one which is new
> 
> 
> Eric Auger (5):
>   qdev: Introduce DEFINE_PROP_RESERVED_REGION
>   virtio-iommu: Implement RESV_MEM probe request
>   virtio-iommu: Handle reserved regions in the translation process
>   virtio-iommu-pci: Add array of Interval properties
>   hw/arm/virt: Let the virtio-iommu bypass MSIs
> 
>  include/exec/memory.h            |   6 ++
>  include/hw/arm/virt.h            |   7 ++
>  include/hw/qdev-properties.h     |   3 +
>  include/hw/virtio/virtio-iommu.h |   2 +
>  include/qemu/typedefs.h          |   1 +
>  hw/arm/virt.c                    |  18 +++++
>  hw/core/qdev-properties.c        |  89 ++++++++++++++++++++++++
>  hw/virtio/virtio-iommu-pci.c     |   3 +
>  hw/virtio/virtio-iommu.c         | 112 +++++++++++++++++++++++++++++--
>  hw/virtio/trace-events           |   1 +
>  10 files changed, 238 insertions(+), 4 deletions(-)
> 
> -- 
> 2.20.1