From: Zhenzhong Duan <zhenzhong.duan@intel.com>

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 | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 019d1c9c800cde1d84f50e29eac02bea0e3329f3..37c21a0aec655770f5b0190c9e4edcf63f8057fa 100644
--- a/hw/i386/intel_iommu.c
+++ b/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;
-- 
2.45.2