[v3,2/5] hw/i386/intel-iommu: Migrate to 3-phase reset

Commit Message

Eric Auger Feb. 18, 2025, 6:25 p.m. UTC

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 <[e-mail]>
Acked-by: Michael S. Tsirkin <[e-mail]>
Acked-by: Jason Wang <[e-mail]>
Zhenzhong Duan <[e-mail]>

---

v1 -> v2:
- add a comment emphasizing the importance of using an 'exit reset
---
 hw/i386/intel_iommu.c | 12 +++++++++---
 hw/i386/trace-events  |  1 +
 2 files changed, 10 insertions(+), 3 deletions(-)

Patch

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;
diff --git a/hw/i386/trace-events b/hw/i386/trace-events
index 53c02d7ac8..ac9e1a10aa 100644
--- a/hw/i386/trace-events
+++ b/hw/i386/trace-events
@@ -68,6 +68,7 @@  vtd_frr_new(int index, uint64_t hi, uint64_t lo) "index %d high 0x%"PRIx64" low
 vtd_warn_invalid_qi_tail(uint16_t tail) "tail 0x%"PRIx16
 vtd_warn_ir_vector(uint16_t sid, int index, int vec, int target) "sid 0x%"PRIx16" index %d vec %d (should be: %d)"
 vtd_warn_ir_trigger(uint16_t sid, int index, int trig, int target) "sid 0x%"PRIx16" index %d trigger %d (should be: %d)"
+vtd_reset_exit(void) ""
 
 # amd_iommu.c
 amdvi_evntlog_fail(uint64_t addr, uint32_t head) "error: fail to write at addr 0x%"PRIx64" +  offset 0x%"PRIx32