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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: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20190916080718.3299-4-peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Peter Xu 2019-09-16 16:07:17 +08:00 committed by Michael S. Tsirkin
parent d2321d31ff
commit c6cbc29d36
1 changed files with 21 additions and 0 deletions
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21
hw/i386/pc.c
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@ -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;