pc-bios/s390-ccw: Remove panics from Netboot IPL path

Remove panic-on-error from Netboot specific functions so that error recovery
may be possible in the future.

Functions that would previously panic now provide a return code.

Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20241020012953.1380075-12-jrossi@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 652807a..95ef910 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -1072,6 +1072,7 @@
 
     if (virtio_get_device_type() == VIRTIO_ID_NET) {
         netmain();
+        panic("\n! Cannot IPL from this network !\n");
     }
 
     if (ipl_scsi()) {
diff --git a/pc-bios/s390-ccw/netmain.c b/pc-bios/s390-ccw/netmain.c
index bc6ad86..d1a6c9a 100644
--- a/pc-bios/s390-ccw/netmain.c
+++ b/pc-bios/s390-ccw/netmain.c
@@ -464,7 +464,7 @@
     return false;
 }
 
-static void virtio_setup(void)
+static bool virtio_setup(void)
 {
     Schib schib;
     int ssid;
@@ -495,10 +495,10 @@
         }
     }
 
-    IPL_assert(found, "No virtio net device found");
+    return found;
 }
 
-void netmain(void)
+int netmain(void)
 {
     filename_ip_t fn_ip;
     int rc, fnlen;
@@ -506,11 +506,15 @@
     sclp_setup();
     puts("Network boot starting...");
 
-    virtio_setup();
+    if (!virtio_setup()) {
+        puts("No virtio net device found.");
+        return -1;
+    }
 
     rc = net_init(&fn_ip);
     if (rc) {
-        panic("Network initialization failed. Halting.");
+        puts("Network initialization failed.");
+        return -1;
     }
 
     fnlen = strlen(fn_ip.filename);
@@ -528,5 +532,6 @@
         jump_to_low_kernel();
     }
 
-    panic("Failed to load OS from network.");
+    puts("Failed to load OS from network.");
+    return -1;
 }
diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index 3e844ab..344ad15 100644
--- a/pc-bios/s390-ccw/s390-ccw.h
+++ b/pc-bios/s390-ccw/s390-ccw.h
@@ -57,7 +57,7 @@
 void main(void);
 
 /* netmain.c */
-void netmain(void);
+int netmain(void);
 
 /* sclp.c */
 void sclp_print(const char *string);
diff --git a/pc-bios/s390-ccw/virtio-net.c b/pc-bios/s390-ccw/virtio-net.c
index 2fcb0a5..f9854a2 100644
--- a/pc-bios/s390-ccw/virtio-net.c
+++ b/pc-bios/s390-ccw/virtio-net.c
@@ -54,8 +54,11 @@
     vdev->guest_features[0] = VIRTIO_NET_F_MAC_BIT;
     virtio_setup_ccw(vdev);
 
-    IPL_assert(vdev->guest_features[0] & VIRTIO_NET_F_MAC_BIT,
-               "virtio-net device does not support the MAC address feature");
+    if (!(vdev->guest_features[0] & VIRTIO_NET_F_MAC_BIT)) {
+        puts("virtio-net device does not support the MAC address feature");
+        return -1;
+    }
+
     memcpy(mac_addr, vdev->config.net.mac, ETH_ALEN);
 
     for (i = 0; i < 64; i++) {