s390-bios: Use control unit type to find bootable devices

When the user does not specify which device to boot from then we end
up guessing. Instead of simply grabbing the first available device let's
be a little bit smarter and only choose devices that might be bootable
like disk, and not console devices.

Signed-off-by: Jason J. Herne <jjherne@linux.ibm.com>
Message-Id: <1554388475-18329-17-git-send-email-jjherne@linux.ibm.com>
[thuth: Added fix for virtio_is_supported() not being called anymore]
Signed-off-by: Thomas Huth <thuth@redhat.com>

1 files changed, 35 insertions, 10 deletions

diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
index 3c449ad496..a69c73349e 100644
--- a/pc-bios/s390-ccw/main.c
+++ b/pc-bios/s390-ccw/main.c
@@ -21,6 +21,7 @@ static char loadparm_str[LOADPARM_LEN + 1] = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 QemuIplParameters qipl;
 IplParameterBlock iplb __attribute__((__aligned__(PAGE_SIZE)));
 static bool have_iplb;
+static uint16_t cutype;
 LowCore const *lowcore; /* Yes, this *is* a pointer to address 0 */
 
 #define LOADPARM_PROMPT "PROMPT  "
@@ -58,11 +59,15 @@ unsigned int get_loadparm_index(void)
  * subchannel information block (schib) with the connected subchannel's info.
  * NOTE: The global variable blk_schid is updated to contain the subchannel
  * information.
+ *
+ * If the caller gives dev_no=-1 then the user did not specify a boot device.
+ * In this case we'll just use the first potentially bootable device we find.
  */
 static bool find_subch(int dev_no)
 {
     Schib schib;
     int i, r;
+    bool is_virtio;
 
     for (i = 0; i < 0x10000; i++) {
         blk_schid.sch_no = i;
@@ -74,16 +79,39 @@ static bool find_subch(int dev_no)
             continue;
         }
 
-        /* Skip net devices since no IPLB is created and therefore no
-         * network bootloader has been loaded
-         */
         enable_subchannel(blk_schid);
-        if (virtio_is_supported(blk_schid) &&
-            virtio_get_device_type() == VIRTIO_ID_NET && dev_no < 0) {
-            continue;
+        cutype = cu_type(blk_schid);
+
+        /*
+         * Note: we always have to run virtio_is_supported() here to make
+         * sure that the vdev.senseid data gets pre-initialized correctly
+         */
+        is_virtio = virtio_is_supported(blk_schid);
+
+        /* No specific devno given, just return 1st possibly bootable device */
+        if (dev_no < 0) {
+            switch (cutype) {
+            case CU_TYPE_VIRTIO:
+                if (is_virtio) {
+                    /*
+                     * Skip net devices since no IPLB is created and therefore
+                     * no network bootloader has been loaded
+                     */
+                    if (virtio_get_device_type() != VIRTIO_ID_NET) {
+                        return true;
+                    }
+                }
+                continue;
+            case CU_TYPE_DASD_3990:
+            case CU_TYPE_DASD_2107:
+                return true;
+            default:
+                continue;
+            }
         }
 
-        if ((dev_no < 0) || (schib.pmcw.dev == dev_no)) {
+        /* Caller asked for a specific devno */
+        if (schib.pmcw.dev == dev_no) {
             return true;
         }
     }
@@ -200,15 +228,12 @@ static void virtio_setup(void)
 
 int main(void)
 {
-    uint16_t cutype;
-
     sclp_setup();
     css_setup();
     boot_setup();
     find_boot_device();
     enable_subchannel(blk_schid);
 
-    cutype = cu_type(blk_schid);
     switch (cutype) {
     case CU_TYPE_DASD_3990:
     case CU_TYPE_DASD_2107: