intel_iommu: simplify irq region translation

Now we have a standalone memory region for MSI, all the irq region
requests should be redirected there. Cleaning up the block with an
assertion instead.

Reviewed-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/intel_iommu.c

@@ -818,28 +818,12 @@ static void vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus,
     bool writes = true;
     VTDIOTLBEntry *iotlb_entry;
 
-    /* Check if the request is in interrupt address range */
-    if (vtd_is_interrupt_addr(addr)) {
-        if (is_write) {
-            /* FIXME: since we don't know the length of the access here, we
-             * treat Non-DWORD length write requests without PASID as
-             * interrupt requests, too. Withoud interrupt remapping support,
-             * we just use 1:1 mapping.
-             */
-            VTD_DPRINTF(MMU, "write request to interrupt address "
-                        "gpa 0x%"PRIx64, addr);
-            entry->iova = addr & VTD_PAGE_MASK_4K;
-            entry->translated_addr = addr & VTD_PAGE_MASK_4K;
-            entry->addr_mask = ~VTD_PAGE_MASK_4K;
-            entry->perm = IOMMU_WO;
-            return;
-        } else {
-            VTD_DPRINTF(GENERAL, "error: read request from interrupt address "
-                        "gpa 0x%"PRIx64, addr);
-            vtd_report_dmar_fault(s, source_id, addr, VTD_FR_READ, is_write);
-            return;
-        }
-    }
+    /*
+     * We have standalone memory region for interrupt addresses, we
+     * should never receive translation requests in this region.
+     */
+    assert(!vtd_is_interrupt_addr(addr));
+
     /* Try to fetch slpte form IOTLB */
     iotlb_entry = vtd_lookup_iotlb(s, source_id, addr);
     if (iotlb_entry) {