From 911dc631f9ab68c6acfd4b401fbcfaa3b58a4fb6 Mon Sep 17 00:00:00 2001

From: Thomas Huth <thuth@redhat.com>

Date: Fri, 9 Oct 2020 10:08:46 -0400

Subject: [PATCH 10/14] pc-bios/s390-ccw: Scan through all devices if no boot

 device specified

RH-Author: Thomas Huth <thuth@redhat.com>

Message-id: <20201009100849.264994-7-thuth@redhat.com>

Patchwork-id: 98600

O-Subject: [RHEL-8.4.0 qemu-kvm PATCH 6/9] pc-bios/s390-ccw: Scan through all devices if no boot device specified

Bugzilla: 1846975

RH-Acked-by: Jens Freimann <jfreimann@redhat.com>

RH-Acked-by: David Hildenbrand <david@redhat.com>

RH-Acked-by: Cornelia Huck <cohuck@redhat.com>

If no boot device has been specified (via "bootindex=..."), the s390-ccw

bios scans through all devices to find a bootable device. But so far, it

stops at the very first block device (including virtio-scsi controllers

without attached devices) that it finds, no matter whether it is bootable

or not. That leads to some weird situatation where it is e.g. possible

to boot via:

 qemu-system-s390x -hda /path/to/disk.qcow2

but not if there is e.g. a virtio-scsi controller specified before:

 qemu-system-s390x -device virtio-scsi -hda /path/to/disk.qcow2

While using "bootindex=..." is clearly the preferred way of booting

on s390x, we still can make the life for the users at least a little

bit easier if we look at all available devices to find a bootable one.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1846975

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Message-Id: <20200806105349.632-7-thuth@redhat.com>

Signed-off-by: Thomas Huth <thuth@redhat.com>

(cherry picked from commit 869d0e2f593dd37297c366203f006b9acd1b7b45)

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 pc-bios/s390-ccw/main.c | 46 +++++++++++++++++++++++++++--------------

 1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c

index 456733fbee..5c1c98341d 100644

--- a/pc-bios/s390-ccw/main.c

+++ b/pc-bios/s390-ccw/main.c

@@ -191,20 +191,8 @@ static void boot_setup(void)

 static void find_boot_device(void)

 {

     VDev *vdev = virtio_get_device();

-    int ssid;

     bool found;

-    if (!have_iplb) {

-        for (ssid = 0; ssid < 0x3; ssid++) {

-            blk_schid.ssid = ssid;

-            found = find_subch(-1);

-            if (found) {

-                return;

-            }

-        }

-        panic("Could not find a suitable boot device (none specified)\n");

-    }

-

     switch (iplb.pbt) {

     case S390_IPL_TYPE_CCW:

         debug_print_int("device no. ", iplb.ccw.devno);

@@ -270,14 +258,42 @@ static void ipl_boot_device(void)

     }

 }

+/*

+ * No boot device has been specified, so we have to scan through the

+ * channels to find one.

+ */

+static void probe_boot_device(void)

+{

+    int ssid, sch_no, ret;

+

+    for (ssid = 0; ssid < 0x3; ssid++) {

+        blk_schid.ssid = ssid;

+        for (sch_no = 0; sch_no < 0x10000; sch_no++) {

+            ret = is_dev_possibly_bootable(-1, sch_no);

+            if (ret < 0) {

+                break;

+            }

+            if (ret == true) {

+                ipl_boot_device();      /* Only returns if unsuccessful */

+            }

+        }

+    }

+

+    sclp_print("Could not find a suitable boot device (none specified)\n");

+}

+

 int main(void)

 {

     sclp_setup();

     css_setup();

     boot_setup();

-    find_boot_device();

-    enable_subchannel(blk_schid);

-    ipl_boot_device();

+    if (have_iplb) {

+        find_boot_device();

+        enable_subchannel(blk_schid);

+        ipl_boot_device();

+    } else {

+        probe_boot_device();

+    }

     panic("Failed to load OS from hard disk\n");

     return 0; /* make compiler happy */

-- 

2.27.0