diff --git a/qubes/app.py b/qubes/app.py
index 016a3cd9..8b7c9398 100644
--- a/qubes/app.py
+++ b/qubes/app.py
@@ -314,6 +314,16 @@ class QubesHost:
             raise NotImplementedError('This function requires Xen hypervisor')
         return int(self._physinfo['free_memory'])
 
+    def is_iommu_supported(self):
+        """Check if IOMMU is supported on this platform"""
+        if self._physinfo is None:
+            try:
+                self._physinfo = self.app.vmm.xc.physinfo()
+            except AttributeError:
+                raise NotImplementedError(
+                    'This function requires Xen hypervisor')
+        return 'hvm_directio' in self._physinfo['virt_caps']
+
     def get_vm_stats(self, previous_time=None, previous=None, only_vm=None):
         """Measure cpu usage for all domains at once.
 
diff --git a/qubes/vm/qubesvm.py b/qubes/vm/qubesvm.py
index 2aea4330..9df7190f 100644
--- a/qubes/vm/qubesvm.py
+++ b/qubes/vm/qubesvm.py
@@ -1115,6 +1115,19 @@ class QubesVM(qubes.vm.mix.net.NetVMMixin, qubes.vm.BaseVM):
                 self.libvirt_domain.createWithFlags(
                     libvirt.VIR_DOMAIN_START_PAUSED)
 
+            except libvirt.libvirtError as exc:
+                # missing IOMMU?
+                if self.virt_mode == 'hvm' and \
+                        list(self.devices['pci'].persistent()) and \
+                        not self.app.host.is_iommu_supported():
+                    exc = qubes.exc.QubesException(
+                        'Failed to start an HVM qube with PCI devices assigned '
+                        '- hardware does not support IOMMU/VT-d/AMD-Vi')
+                self.log.error('Start failed: %s', str(exc))
+                yield from self.fire_event_async('domain-start-failed',
+                                                 reason=str(exc))
+                yield from self.storage.stop()
+                raise exc
             except Exception as exc:
                 self.log.error('Start failed: %s', str(exc))
                 # let anyone receiving domain-pre-start know that startup failed