Add an new element scalable_mode in IntelIOMMUState to mark scalable
modern mode, this element will be exposed as an intel_iommu property
finally.

For now, it's only a placehholder and used for address width
compatibility check and block host device passthrough until nesting
is supported.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Clément Mathieu--Drif<clement.mathieu--drif@eviden.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
---
 include/hw/i386/intel_iommu.h |  1 +
 hw/i386/intel_iommu.c         | 23 ++++++++++++++++++-----
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index d372cd396b..3d65bbbd56 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -262,6 +262,7 @@ struct IntelIOMMUState {
 
     bool caching_mode;              /* RO - is cap CM enabled? */
     bool scalable_mode;             /* RO - is Scalable Mode supported? */
+    bool scalable_modern;           /* RO - is modern SM supported? */
     bool snoop_control;             /* RO - is SNP filed supported? */
 
     dma_addr_t root;                /* Current root table pointer */
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 10b8425a6c..1d13916a98 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3918,7 +3918,13 @@ static bool vtd_check_hiod(IntelIOMMUState *s, HostIOMMUDevice *hiod,
         return false;
     }
 
-    return true;
+    if (!s->scalable_modern) {
+        /* All checks requested by VTD non-modern mode pass */
+        return true;
+    }
+
+    error_setg(errp, "host device is unsupported in scalable modern mode yet");
+    return false;
 }
 
 static bool vtd_dev_set_iommu_device(PCIBus *bus, void *opaque, int devfn,
@@ -4308,14 +4314,21 @@ static bool vtd_decide_config(IntelIOMMUState *s, Error **errp)
         }
     }
 
-    /* Currently only address widths supported are 39 and 48 bits */
-    if ((s->aw_bits != VTD_HOST_AW_39BIT) &&
-        (s->aw_bits != VTD_HOST_AW_48BIT)) {
-        error_setg(errp, "Supported values for aw-bits are: %d, %d",
+    if (!s->scalable_modern && s->aw_bits != VTD_HOST_AW_39BIT &&
+        s->aw_bits != VTD_HOST_AW_48BIT) {
+        error_setg(errp, "%s mode: supported values for aw-bits are: %d, %d",
+                   s->scalable_mode ? "Scalable" : "Legacy",
                    VTD_HOST_AW_39BIT, VTD_HOST_AW_48BIT);
         return false;
     }
 
+    if (s->scalable_modern && s->aw_bits != VTD_HOST_AW_48BIT) {
+        error_setg(errp,
+                   "Scalable modern mode: supported values for aw-bits is: %d",
+                   VTD_HOST_AW_48BIT);
+        return false;
+    }
+
     if (s->scalable_mode && !s->dma_drain) {
         error_setg(errp, "Need to set dma_drain for scalable mode");
         return false;
-- 
2.34.1