Intel vIOMMU devices are created with "-device" parameter, while here actually we need to make sure the dmar device be created before other PCI devices (like vfio-pci, virtio-pci ones) so that we know iommu_fn will be setup correctly before realizations of those PCI devices (it is legal that PCI device fetch these info during its realization). Now this ordering yet cannot be achieved elsewhere, and devices will be created in the order that user specified. We need to avoid that.
This patch tries to detect this kind of misordering issue during init of VT-d device, then report to guest if misordering happened. In the future, we can provide something better to solve it, e.g., to support device init ordering, then we can live without this patch. Signed-off-by: Peter Xu <pet...@redhat.com> --- v3: added virtio-pci device detection since we have that requirement as well now. PS. this patch should be needed along with Jason's: "virtio: unbreak virtio-pci with IOMMU after caching ring translations" to make sure virtio devices with vt-d are safe for 2.9. --- hw/i386/intel_iommu.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index 22d8226..1077f90 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -2560,6 +2560,24 @@ static bool vtd_decide_config(IntelIOMMUState *s, Error **errp) return true; } +/* + * TODO: we should have a better way to achieve the ordering rather + * than this misorder check explicitly against vfio-pci and virtio-pci + * devices. Here, there's no easy way to detect init of virtio-pci + * devices, instead we detect the virtio bus. + */ +static bool vtd_detected_misorder_init(Error **errp) +{ + if (object_resolve_path_type("", "vfio-pci", NULL) || + object_resolve_path_type("", "virtio-pci-bus", NULL)) { + error_setg(errp, "Please specify \"intel-iommu\" before " + "all the rest of the devices."); + return true; + } + + return false; +} + static void vtd_realize(DeviceState *dev, Error **errp) { PCMachineState *pcms = PC_MACHINE(qdev_get_machine()); @@ -2567,6 +2585,10 @@ static void vtd_realize(DeviceState *dev, Error **errp) IntelIOMMUState *s = INTEL_IOMMU_DEVICE(dev); X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(dev); + if (vtd_detected_misorder_init(errp)) { + return; + } + VTD_DPRINTF(GENERAL, ""); x86_iommu->type = TYPE_INTEL; -- 2.7.4