Without caching mode, MAP notifier won't work correctly since guest won't send IOTLB update event when it establishes new mappings in the I/O page tables. Let's fail the IOMMU notifiers early instead of misbehaving silently.
Reviewed-by: Eric Auger <eric.au...@redhat.com> Tested-by: Viktor Prutyanov <vik...@daynix.com> Signed-off-by: Jason Wang <jasow...@redhat.com> --- hw/i386/intel_iommu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index 98a5c304a7..0de3e31577 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -3186,6 +3186,13 @@ static int vtd_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu, "Snoop Control with vhost or VFIO is not supported"); return -ENOTSUP; } + if (!s->caching_mode && (new & IOMMU_NOTIFIER_MAP)) { + error_setg_errno(errp, ENOTSUP, + "device %02x.%02x.%x requires caching mode", + pci_bus_num(vtd_as->bus), PCI_SLOT(vtd_as->devfn), + PCI_FUNC(vtd_as->devfn)); + return -ENOTSUP; + } /* Update per-address-space notifier flags */ vtd_as->notifier_flags = new; -- 2.25.1