2 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index b4b61d462dcc..e60530a5f524 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -1330,6 +1330,8 @@ void __init amd_iommu_detect(void)
                 gart_iommu_aperture_disabled = 1;
                 gart_iommu_aperture = 0;
 #endif
+                /* Make sure ACS will be enabled */
+                pci_request_acs();
         }
 }
 
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 5bccd706232c..e2511bccbc8d 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -27,6 +27,7 @@
 #include <linux/page-flags.h>
 #include <linux/highmem.h>
 #include <linux/console.h>
+#include <linux/pci.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
@@ -1170,7 +1171,11 @@ asmlinkage void __init xen_start_kernel(void)
                 add_preferred_console("xenboot", 0, NULL);
                 add_preferred_console("tty", 0, NULL);
                 add_preferred_console("hvc", 0, NULL);
+        } else {
+                /* Make sure ACS will be enabled */
+                pci_request_acs();
         }
+                
 
         xen_raw_console_write("about to get started...\n");