Commit c6cbc29d authored by Peter Xu's avatar Peter Xu Committed by Michael S. Tsirkin
Browse files

pc/q35: Disallow vfio-pci hotplug without VT-d caching mode 



Instead of bailing out when trying to hotplug a vfio-pci device with
below configuration:

  -device intel-iommu,caching-mode=off

With this we can return a warning message to the user via QMP/HMP and
the VM will continue to work after failing the hotplug:

  (qemu) device_add vfio-pci,bus=root.3,host=05:00.0,id=vfio1
  Error: Device assignment is not allowed without enabling caching-mode=on for Intel IOMMU.

Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <20190916080718.3299-4-peterx@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent d2321d31

hw/i386/pc.c

+21 −0
Original line number Diff line number Diff line
@@ -2944,6 +2944,26 @@ static void x86_nmi(NMIState *n, int cpu_index, Error **errp) 
    }

}





static bool pc_hotplug_allowed(MachineState *ms, DeviceState *dev, Error **errp)

{

    X86IOMMUState *iommu = x86_iommu_get_default();

    IntelIOMMUState *intel_iommu;



    if (iommu &&

        object_dynamic_cast((Object *)iommu, TYPE_INTEL_IOMMU_DEVICE) &&

        object_dynamic_cast((Object *)dev, "vfio-pci")) {

        intel_iommu = INTEL_IOMMU_DEVICE(iommu);

        if (!intel_iommu->caching_mode) {

            error_setg(errp, "Device assignment is not allowed without "

                       "enabling caching-mode=on for Intel IOMMU.");

            return false;

        }

    }



    return true;

}



static void pc_machine_class_init(ObjectClass *oc, void *data)

{

    MachineClass *mc = MACHINE_CLASS(oc);
@@ -2968,6 +2988,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data) 
    pcmc->pvh_enabled = true;

    assert(!mc->get_hotplug_handler);

    mc->get_hotplug_handler = pc_get_hotplug_handler;

    mc->hotplug_allowed = pc_hotplug_allowed;

    mc->cpu_index_to_instance_props = pc_cpu_index_to_props;

    mc->get_default_cpu_node_id = pc_get_default_cpu_node_id;

    mc->possible_cpu_arch_ids = pc_possible_cpu_arch_ids;