Xen can support console_io hypercalls for any domains, not just dom0,
depending on DEBUG and XSM policies. These hypercalls can be very useful
for development and debugging.
Introduce a kernel command line option xen_console_io to enable the
usage of console_io hypercalls for any domain upon request. When
xen_console_io is not specified, the current behavior is retained.
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
---
.../admin-guide/kernel-parameters.txt | 5 +++
drivers/tty/hvc/hvc_xen.c | 33 ++++++++++++++++---
2 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index e88505e945d52..953d3f597f007 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -7620,6 +7620,11 @@
save/restore/migration must be enabled to handle larger
domains.
+ xen_console_io [XEN,EARLY]
+ Boolean option to enable/disable the usage of the Xen
+ console_io hypercalls to read and write to the console.
+ Mostly useful for debugging and development.
+
xen_emul_unplug= [HW,X86,XEN,EARLY]
Unplug Xen emulated devices
Format: [unplug0,][unplug1]
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 388a71afd6efe..299b08c90bab1 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -51,6 +51,28 @@ static DEFINE_SPINLOCK(xencons_lock);
/* ------------------------------------------------------------------ */
+static bool xen_console_io = false;
+static int __initdata opt_console_io = -1;
+
+static int __init parse_xen_console_io(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ if (strcmp(arg, "off") == 0 ||
+ strcmp(arg, "disabled") == 0 ||
+ strcmp(arg, "0") == 0) {
+ opt_console_io = 0;
+ }
+ else if (strcmp(arg, "on") == 0 ||
+ strcmp(arg, "enabled") == 0 ||
+ strcmp(arg, "1") == 0) {
+ opt_console_io = 1;
+ }
