s390-ccw: use zipl values when no boot menu options are present

If no boot menu options are present, then flag the boot menu to
use the zipl options that were set in the zipl configuration file
(and stored on disk by zipl). These options are found at some
offset prior to the start of the zipl boot menu banner. The zipl
timeout value is limited to a 16-bit unsigned integer and stored
as seconds, so we take care to convert it to milliseconds in order
to conform to the rest of the boot menu functionality. This is
limited to CCW devices.

For reference, the zipl configuration file uses the following
fields in the menu section:

      prompt=1      enable the boot menu
      timeout=X     set the timeout to X seconds

To explicitly disregard any boot menu options, then menu=off or
<bootmenu enable='no' ... /> must be specified.

Signed-off-by: Collin L. Walling <walling@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/pc-bios/s390-ccw/menu.c b/pc-bios/s390-ccw/menu.c
index 8d55869448..ee56939c21 100644
--- a/pc-bios/s390-ccw/menu.c
+++ b/pc-bios/s390-ccw/menu.c
@@ -18,6 +18,10 @@
 #define KEYCODE_BACKSP '\177'
 #define KEYCODE_ENTER  '\r'
 
+/* Offsets from zipl fields to zipl banner start */
+#define ZIPL_TIMEOUT_OFFSET 138
+#define ZIPL_FLAG_OFFSET    140
+
 #define TOD_CLOCK_MILLISECOND   0x3e8000
 
 #define LOW_CORE_EXTERNAL_INT_ADDR   0x86
@@ -187,6 +191,16 @@ int menu_get_zipl_boot_index(const char *menu_data)
 {
     size_t len;
     int entries;
+    uint16_t zipl_flag = *(uint16_t *)(menu_data - ZIPL_FLAG_OFFSET);
+    uint16_t zipl_timeout = *(uint16_t *)(menu_data - ZIPL_TIMEOUT_OFFSET);
+
+    if (flag == QIPL_FLAG_BM_OPTS_ZIPL) {
+        if (!zipl_flag) {
+            return 0; /* Boot default */
+        }
+        /* zipl stores timeout as seconds */
+        timeout = zipl_timeout * 1000;
+    }
 
     /* Print and count all menu items, including the banner */
     for (entries = 0; *menu_data; entries++) {
@@ -211,5 +225,5 @@ void menu_set_parms(uint8_t boot_menu_flag, uint32_t boot_menu_timeout)
 
 bool menu_is_enabled_zipl(void)
 {
-    return flag & QIPL_FLAG_BM_OPTS_CMD;
+    return flag & (QIPL_FLAG_BM_OPTS_CMD | QIPL_FLAG_BM_OPTS_ZIPL);
 }