3 files changed, 14 insertions, 3 deletions

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index b459edfacff3..90d387b50ab7 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -79,15 +79,19 @@ config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
           This value is used to allocate enough space in internal
           tables needed for physical memory administration.
 
-config XEN_SCRUB_PAGES
-        bool "Scrub pages before returning them to system"
+config XEN_SCRUB_PAGES_DEFAULT
+        bool "Scrub pages before returning them to system by default"
         depends on XEN_BALLOON
         default y
         help
           Scrub pages before returning them to the system for reuse by
           other domains.  This makes sure that any confidential data
           is not accidentally visible to other domains.  Is it more
-          secure, but slightly less efficient.
+          secure, but slightly less efficient. This can be controlled with
+          xen_scrub_pages=0 parameter and
+          /sys/devices/system/xen_memory/xen_memory0/scrub_pages.
+          This option only sets the default value.
+
           If in doubt, say yes.
 
 config XEN_DEV_EVTCHN
diff --git a/drivers/xen/mem-reservation.c b/drivers/xen/mem-reservation.c
index 084799c6180e..3782cf070338 100644
--- a/drivers/xen/mem-reservation.c
+++ b/drivers/xen/mem-reservation.c
@@ -14,6 +14,10 @@
 
 #include <xen/interface/memory.h>
 #include <xen/mem-reservation.h>
+#include <linux/moduleparam.h>
+
+bool __read_mostly xen_scrub_pages = IS_ENABLED(CONFIG_XEN_SCRUB_PAGES_DEFAULT);
+core_param(xen_scrub_pages, xen_scrub_pages, bool, 0);
 
 /*
  * Use one extent per PAGE_SIZE to avoid to break down the page into
diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
index 294f35ce9e46..63c1494a8d73 100644
--- a/drivers/xen/xen-balloon.c
+++ b/drivers/xen/xen-balloon.c
@@ -44,6 +44,7 @@
 #include <xen/xenbus.h>
 #include <xen/features.h>
 #include <xen/page.h>
+#include <xen/mem-reservation.h>
 
 #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
 
@@ -137,6 +138,7 @@ static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
 static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
 static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
 static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
+static DEVICE_BOOL_ATTR(scrub_pages, 0644, xen_scrub_pages);
 
 static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
                               char *buf)
@@ -203,6 +205,7 @@ static struct attribute *balloon_attrs[] = {
         &dev_attr_max_schedule_delay.attr.attr,
         &dev_attr_retry_count.attr.attr,
         &dev_attr_max_retry_count.attr.attr,
+        &dev_attr_scrub_pages.attr.attr,
         NULL
 };