At the moment the virtio-iommu translates MSI transactions. This behavior is inherited from ARM SMMU. The virt machine code knows where the guest MSI doorbells are so we can easily declare those regions as VIRTIO_IOMMU_RESV_MEM_T_MSI. With that setting the guest will not map MSIs through the IOMMU and those transactions will be simply bypassed. The ITS does MSI translation anyway.
Signed-off-by: Eric Auger <eric.au...@redhat.com> --- hw/arm/virt.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/arm/virt.c b/hw/arm/virt.c index 171e6908ec..6a041e97a5 100644 --- a/hw/arm/virt.c +++ b/hw/arm/virt.c @@ -2138,6 +2138,11 @@ static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev, { if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) { virt_memory_pre_plug(hotplug_dev, dev, errp); + } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) { + /* we declare a VIRTIO_IOMMU_RESV_MEM_T_MSI region */ + qdev_prop_set_uint32(dev, "len-reserved-regions", 1); + qdev_prop_set_string(dev, "reserved-regions[0]", + "0x8090000, 0x809FFFF, 1"); } } -- 2.20.1