struct context_entry *context;
        unsigned long flags;
        struct intel_iommu *iommu;
+       struct dma_pte *pgd;
+       unsigned long num;
+       unsigned long ndomains;
+       int id;
+       int agaw;
 
        pr_debug("Set context mapping for %02x:%02x.%d\n",
                bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
                return 0;
        }
 
-       context_set_domain_id(context, domain->id);
-       context_set_address_width(context, domain->agaw);
-       context_set_address_root(context, virt_to_phys(domain->pgd));
+       id = domain->id;
+       pgd = domain->pgd;
+
+       if (domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE) {
+               int found = 0;
+
+               /* find an available domain id for this device in iommu */
+               ndomains = cap_ndoms(iommu->cap);
+               num = find_first_bit(iommu->domain_ids, ndomains);
+               for (; num < ndomains; ) {
+                       if (iommu->domains[num] == domain) {
+                               id = num;
+                               found = 1;
+                               break;
+                       }
+                       num = find_next_bit(iommu->domain_ids,
+                                           cap_ndoms(iommu->cap), num+1);
+               }
+
+               if (found == 0) {
+                       num = find_first_zero_bit(iommu->domain_ids, ndomains);
+                       if (num >= ndomains) {
+                               spin_unlock_irqrestore(&iommu->lock, flags);
+                               printk(KERN_ERR "IOMMU: no free domain ids\n");
+                               return -EFAULT;
+                       }
+
+                       set_bit(num, iommu->domain_ids);
+                       iommu->domains[num] = domain;
+                       id = num;
+               }
+
+               /* Skip top levels of page tables for
+                * iommu which has less agaw than default.
+                */
+               for (agaw = domain->agaw; agaw != iommu->agaw; agaw--) {
+                       pgd = phys_to_virt(dma_pte_addr(pgd));
+                       if (!dma_pte_present(pgd)) {
+                               spin_unlock_irqrestore(&iommu->lock, flags);
+                               return -ENOMEM;
+                       }
+               }
+       }
+
+       context_set_domain_id(context, id);
+       context_set_address_width(context, iommu->agaw);
+       context_set_address_root(context, virt_to_phys(pgd));
        context_set_translation_type(context, CONTEXT_TT_MULTI_LEVEL);
        context_set_fault_enable(context);
        context_set_present(context);