hw/i386/intel-iommu: Migrate to 3-phase reset

Currently the IOMMU may be reset before the devices
it protects. For example this happens with virtio devices
but also with VFIO devices. In this latter case this
produces spurious translation faults on host.

Let's use 3-phase reset mechanism and reset the IOMMU on
exit phase after all DMA capable devices have been reset
on 'enter' or 'hold' phase.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Zhenzhong Duan <zhenzhong.duan@intel.com>

Message-Id: <20250218182737.76722-3-eric.auger@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index f366c223d0..a5cf2d0e81 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -4697,10 +4697,11 @@ static void vtd_init(IntelIOMMUState *s)
 /* Should not reset address_spaces when reset because devices will still use
  * the address space they got at first (won't ask the bus again).
  */
-static void vtd_reset(DeviceState *dev)
+static void vtd_reset_exit(Object *obj, ResetType type)
 {
-    IntelIOMMUState *s = INTEL_IOMMU_DEVICE(dev);
+    IntelIOMMUState *s = INTEL_IOMMU_DEVICE(obj);
 
+    trace_vtd_reset_exit();
     vtd_init(s);
     vtd_address_space_refresh_all(s);
 }
@@ -4864,8 +4865,13 @@ static void vtd_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     X86IOMMUClass *x86_class = X86_IOMMU_DEVICE_CLASS(klass);
+    ResettableClass *rc = RESETTABLE_CLASS(klass);
 
-    device_class_set_legacy_reset(dc, vtd_reset);
+    /*
+     * Use 'exit' reset phase to make sure all DMA requests
+     * have been quiesced during 'enter' or 'hold' phase
+     */
+    rc->phases.exit = vtd_reset_exit;
     dc->vmsd = &vtd_vmstate;
     device_class_set_props(dc, vtd_properties);
     dc->hotpluggable = false;