Revert "hv: init_iommu rework to enable IOMMU for partition mode ACRN"

This reverts commit d8508e4.

Author: wenlingz

hypervisor/arch/x86/vtd.c

@@ -659,18 +659,9 @@ static void dmar_set_root_table(struct dmar_drhd_rt *dmar_uint)
 {
 	uint64_t address;
 	uint32_t status;
-	void *root_table_vaddr = NULL;
 
 	spinlock_obtain(&(dmar_uint->lock));
 
-	root_table_vaddr = alloc_paging_struct();
-
-	if (root_table_vaddr != NULL) {
-		dmar_uint->root_table_addr = hva2hpa(root_table_vaddr);
-	} else {
-		ASSERT(false, "failed to allocate root table!");
-	}
-
 	/* Currently don't support extended root table */
 	address = dmar_uint->root_table_addr;
 
@@ -982,7 +973,16 @@ static int add_iommu_device(struct iommu_domain *domain, uint16_t segment,
 		return 1;
 	}
 
-	ASSERT(dmar_uint->root_table_addr != 0UL, "root table is not setup");
+	if (dmar_uint->root_table_addr == 0UL) {
+		void *root_table_vaddr = alloc_paging_struct();
+
+		if (root_table_vaddr != NULL) {
+			dmar_uint->root_table_addr = hva2hpa(root_table_vaddr);
+		} else {
+			ASSERT(false, "failed to allocate root table!");
+			return 1;
+		}
+	}
 
 	root_table =
 		(struct dmar_root_entry *)hpa2hva(dmar_uint->root_table_addr);
@@ -1277,8 +1277,6 @@ void init_iommu(void)
 	spinlock_init(&domain_lock);
 
 	register_hrhd_units();
-
-	enable_iommu();
 }
 
 void init_iommu_vm0_domain(struct vm *vm0)
@@ -1298,4 +1296,5 @@ void init_iommu_vm0_domain(struct vm *vm0)
 		}
 	}
 	cache_flush_invalidate_all();
+	enable_iommu();
 }