Currently only stage-2 translation is supported which is backed by
shadow page table on host side. So we don't need exact matching of
each bit of cap/ecap between vIOMMU and host. However, we can still
ensure compatibility of host and vIOMMU's address width at least,
i.e., vIOMMU's aw-bits <= host IOMMU aw-bits, which is missed before.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
---
 hw/i386/intel_iommu.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index a49b587c73..d2cd186df0 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3824,6 +3824,21 @@ static int vtd_check_legacy_hdev(IntelIOMMUState *s,
                                  HostIOMMUDevice *hiod,
                                  Error **errp)
 {
+    HostIOMMUDeviceClass *hiodc = HOST_IOMMU_DEVICE_GET_CLASS(hiod);
+    HIOD_LEGACY_INFO info;
+    int ret;
+
+    ret = hiodc->get_host_iommu_info(hiod, &info, sizeof(info), errp);
+    if (ret) {
+        return ret;
+    }
+
+    if (s->aw_bits > info.aw_bits) {
+        error_setg(errp, "aw-bits %d > host aw-bits %d",
+                   s->aw_bits, info.aw_bits);
+        return -EINVAL;
+    }
+
     return 0;
 }
 
-- 
2.34.1