[PATCH] x86-iommu: Fail flag registration of DEVIOTLB if DT not supported

[Peter Xu <peterx@redhat.com>]

All x86 IOMMUs need to fail DEVIOTLB notification registrations if DT is
not supported.  Otherwise any device (e.g. vhost) can register with
DEVIOTLB but it'll never receive the notifications, causing device not
operational.

Fixes: b68ba1ca57 ("memory: Add IOMMU_NOTIFIER_DEVIOTLB_UNMAP IOMMUTLBNotificationType")
Reported-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/i386/amd_iommu.c   | 8 ++++++++
 hw/i386/intel_iommu.c | 7 +++++++
 2 files changed, 15 insertions(+)

diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index 725f69095b..42486e790f 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -1476,6 +1476,7 @@ static int amdvi_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
                                            Error **errp)
 {
     AMDVIAddressSpace *as = container_of(iommu, AMDVIAddressSpace, iommu);
+    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(as->iommu_state);
 
     if (new & IOMMU_NOTIFIER_MAP) {
         error_setg(errp,
@@ -1484,6 +1485,13 @@ static int amdvi_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
                    PCI_FUNC(as->devfn));
         return -EINVAL;
     }
+
+    if ((new & IOMMU_NOTIFIER_DEVIOTLB_UNMAP) && !x86_iommu->dt_supported) {
+        error_setg_errno(errp, ENOTSUP,
+                         "Device-iotlb not declared support for vIOMMU");
+        return -ENOTSUP;
+    }
+
     return 0;
 }
 
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 6524c2ee32..a07d9631b0 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3057,6 +3057,7 @@ static int vtd_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
 {
     VTDAddressSpace *vtd_as = container_of(iommu, VTDAddressSpace, iommu);
     IntelIOMMUState *s = vtd_as->iommu_state;
+    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);
 
     /* TODO: add support for VFIO and vhost users */
     if (s->snoop_control) {
@@ -3065,6 +3066,12 @@ static int vtd_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
         return -ENOTSUP;
     }
 
+    if ((new & IOMMU_NOTIFIER_DEVIOTLB_UNMAP) && !x86_iommu->dt_supported) {
+        error_setg_errno(errp, ENOTSUP,
+                         "Device-iotlb not declared support for vIOMMU");
+        return -ENOTSUP;
+    }
+
     /* Update per-address-space notifier flags */
     vtd_as->notifier_flags = new;
 
-- 
2.37.3