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

[Viktor Prutyanov <viktor@daynix.com>]

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

Viktor Prutyanov (4):
  pci: add handling of Enable bit in ATS Control Register
  virtio-pci: add handling of ATS state change
  memory: add interface for triggering IOMMU notify_flag_changed handler
  vhost: register and change IOMMU flag depending on ATS state

 hw/pci/pci.c                |  1 +
 hw/pci/pcie.c               | 21 +++++++++++++++++++++
 hw/virtio/vhost.c           | 23 +++++++++++++++++++++--
 hw/virtio/virtio-pci.c      | 12 ++++++++++++
 include/exec/memory.h       |  2 ++
 include/hw/pci/pci_device.h |  3 +++
 include/hw/pci/pcie.h       |  4 ++++
 include/hw/virtio/virtio.h  |  2 ++
 softmmu/memory.c            | 12 ++++++++++++
 9 files changed, 78 insertions(+), 2 deletions(-)

-- 
2.21.0