Re: [RFC PATCH v2 0/4] vhost: register and change IOMMU flag depending on ATS state

[Jason Wang <jasowang@redhat.com>]

On Mon, May 1, 2023 at 10:02 AM Viktor Prutyanov <viktor@daynix.com> wrote:
>
> When IOMMU and vhost are enabled together, QEMU tracks IOTLB or
> Device-TLB unmap events depending on whether Device-TLB is enabled. But
> even if Device-TLB and PCI ATS is enabled, the guest can reject to use
> it. For example, this situation appears when Windows Server 2022 is
> running with intel-iommu with device-iotlb=on and virtio-net-pci with
> vhost=on. The guest implies that no address translation info cached in
> device IOTLB and doesn't send device IOTLB invalidation commands. So,
> it leads to irrelevant address translations in vhost-net in the host
> kernel. Therefore network frames from the guest in host tap interface
> contains wrong payload data.
>
> This series adds checking of ATS state for proper unmap flag register
> (IOMMU_NOTIFIER_UNMAP or IOMMU_NOTIFIER_DEVIOTLB_UNMAP).
>
> Tested on Windows Server 2022, Windows 11 and Fedora guests with
>  -device virtio-net-pci,bus=pci.3,netdev=nd0,iommu_platform=on,ats=on
>  -netdev tap,id=nd0,ifname=tap1,script=no,downscript=no,vhost=on
>  -device intel-iommu,intremap=on,eim=on,device-iotlb=on/off
>
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001312

It would be better if we can have a change log here.

Thanks

>
> Viktor Prutyanov (4):
>   pci: add handling of Enable bit in ATS Control Register
>   virtio-pci: add handling of ATS and Device-TLB enable
>   vhost: register and change IOMMU flag depending on Device-TLB state
>   virtio-net: pass Device-TLB enable/disable events to vhost
>
>  hw/net/vhost_net.c                | 11 +++++++++++
>  hw/net/virtio-net.c               |  8 ++++++++
>  hw/pci/pcie.c                     | 22 ++++++++++++++++++++++
>  hw/virtio/vhost-backend.c         |  6 ++++++
>  hw/virtio/vhost.c                 | 26 ++++++++++++++++++++++++--
>  hw/virtio/virtio-pci.c            | 17 +++++++++++++++++
>  include/hw/pci/pcie.h             |  5 +++++
>  include/hw/virtio/vhost-backend.h |  4 ++++
>  include/hw/virtio/vhost.h         |  1 +
>  include/hw/virtio/virtio.h        |  2 ++
>  include/net/vhost_net.h           |  2 ++
>  11 files changed, 102 insertions(+), 2 deletions(-)
>
> --
> 2.35.1
>