disallow interrupt remapping if not all ioapic under interrupt remapping

disallow interrupt remapping if not all ioapic under interrupt remapping

[Youquan Song]

Current kernel enable interrupt remapping only when all the vt-d unit support
interrupt remapping. So it is reasonable we should also disallow enabling
intr-remapping if there any io-apics that are not listed under vt-d units. 
Otherwise we can run into issues.

Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> 
Signed-off-by: Youquan Song <youquan.song@intel.com>
---

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 7b287cb..a8a4383 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -570,9 +570,6 @@ int __init dmar_table_init(void)
 		printk(KERN_INFO PREFIX "No ATSR found\n");
 #endif
 
-#ifdef CONFIG_INTR_REMAP
-	parse_ioapics_under_ir();
-#endif
 	return 0;
 }
 
diff --git a/drivers/pci/intr_remapping.c b/drivers/pci/intr_remapping.c
index 4f5b871..ebfa47b 100644
--- a/drivers/pci/intr_remapping.c
+++ b/drivers/pci/intr_remapping.c
@@ -626,6 +626,11 @@ int __init enable_intr_remapping(int eim)
 	struct dmar_drhd_unit *drhd;
 	int setup = 0;
 
+	if (parse_ioapics_under_ir() != 1) {
+		printk(KERN_INFO "Not enable interrupt remapping\n");
+		return -1;
+	}
+
 	for_each_drhd_unit(drhd) {
 		struct intel_iommu *iommu = drhd->iommu;