intel_iommu: Check compatibility with host IOMMU capabilities

If check fails, host device (either VFIO or VDPA device) is not
compatible with current vIOMMU config and should not be passed to
guest.

Only aw_bits is checked for now, we don't care about other caps
before scalable modern mode is introduced.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/intel_iommu.c

@@ -3837,6 +3837,30 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus,
     return vtd_dev_as;
 }
 
+static bool vtd_check_hiod(IntelIOMMUState *s, HostIOMMUDevice *hiod,
+                           Error **errp)
+{
+    HostIOMMUDeviceClass *hiodc = HOST_IOMMU_DEVICE_GET_CLASS(hiod);
+    int ret;
+
+    if (!hiodc->get_cap) {
+        error_setg(errp, ".get_cap() not implemented");
+        return false;
+    }
+
+    /* Common checks */
+    ret = hiodc->get_cap(hiod, HOST_IOMMU_DEVICE_CAP_AW_BITS, errp);
+    if (ret < 0) {
+        return false;
+    }
+    if (s->aw_bits > ret) {
+        error_setg(errp, "aw-bits %d > host aw-bits %d", s->aw_bits, ret);
+        return false;
+    }
+
+    return true;
+}
+
 static bool vtd_dev_set_iommu_device(PCIBus *bus, void *opaque, int devfn,
                                      HostIOMMUDevice *hiod, Error **errp)
 {
@@ -3857,6 +3881,11 @@ static bool vtd_dev_set_iommu_device(PCIBus *bus, void *opaque, int devfn,
         return false;
     }
 
+    if (!vtd_check_hiod(s, hiod, errp)) {
+        vtd_iommu_unlock(s);
+        return false;
+    }
+
     new_key = g_malloc(sizeof(*new_key));
     new_key->bus = bus;
     new_key->devfn = devfn;