pc-bios/s390-ccw: Do not bail out early if not finding a SCSI disk

In case the user did not specify a boot device, we want to continue
looking for other devices if there are no valid SCSI disks on a virtio-
scsi controller. As a first step, do not panic in this case and let
the control flow carry the error to the upper functions instead.

Message-Id: <20200806105349.632-6-thuth@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

pc-bios/s390-ccw/main.c

@@ -218,7 +218,7 @@ static void find_boot_device(void)
     IPL_assert(found, "Boot device not found\n");
 }
 
-static void virtio_setup(void)
+static int virtio_setup(void)
 {
     VDev *vdev = virtio_get_device();
     QemuIplParameters *early_qipl = (QemuIplParameters *)QIPL_ADDRESS;
@@ -233,9 +233,14 @@ static void virtio_setup(void)
         sclp_print("Network boot device detected\n");
         vdev->netboot_start_addr = qipl.netboot_start_addr;
     } else {
-        virtio_blk_setup_device(blk_schid);
+        int ret = virtio_blk_setup_device(blk_schid);
+        if (ret) {
+            return ret;
+        }
         IPL_assert(virtio_ipl_disk_is_valid(), "No valid IPL device detected");
     }
+
+    return 0;
 }
 
 static void ipl_boot_device(void)
@@ -246,8 +251,9 @@ static void ipl_boot_device(void)
         dasd_ipl(blk_schid, cutype); /* no return */
         break;
     case CU_TYPE_VIRTIO:
-        virtio_setup();
-        zipl_load(); /* no return */
+        if (virtio_setup() == 0) {
+            zipl_load(); /* no return */
+        }
         break;
     default:
         print_int("Attempting to boot from unexpected device type", cutype);

pc-bios/s390-ccw/s390-ccw.h

@@ -69,7 +69,7 @@ int sclp_read(char *str, size_t count);
 unsigned long virtio_load_direct(ulong rec_list1, ulong rec_list2,
                                  ulong subchan_id, void *load_addr);
 bool virtio_is_supported(SubChannelId schid);
-void virtio_blk_setup_device(SubChannelId schid);
+int virtio_blk_setup_device(SubChannelId schid);
 int virtio_read(ulong sector, void *load_addr);
 
 /* bootmap.c */

pc-bios/s390-ccw/virtio-blkdev.c

@@ -263,9 +263,10 @@ uint64_t virtio_get_blocks(void)
     return 0;
 }
 
-void virtio_blk_setup_device(SubChannelId schid)
+int virtio_blk_setup_device(SubChannelId schid)
 {
     VDev *vdev = virtio_get_device();
+    int ret = 0;
 
     vdev->schid = schid;
     virtio_setup_ccw(vdev);
@@ -288,9 +289,11 @@ void virtio_blk_setup_device(SubChannelId schid)
             "Config: CDB size mismatch");
 
         sclp_print("Using virtio-scsi.\n");
-        virtio_scsi_setup(vdev);
+        ret = virtio_scsi_setup(vdev);
         break;
     default:
         panic("\n! No IPL device available !\n");
     }
+
+    return ret;
 }

pc-bios/s390-ccw/virtio-scsi.c

@@ -194,7 +194,12 @@ static bool scsi_read_capacity(VDev *vdev,
 
 /* virtio-scsi routines */
 
-static void virtio_scsi_locate_device(VDev *vdev)
+/*
+ * Tries to locate a SCSI device and and adds the information for the found
+ * device to the vdev->scsi_device structure.
+ * Returns 0 if SCSI device could be located, or a error code < 0 otherwise
+ */
+static int virtio_scsi_locate_device(VDev *vdev)
 {
     const uint16_t channel = 0; /* again, it's what QEMU does */
     uint16_t target;
@@ -220,7 +225,7 @@ static void virtio_scsi_locate_device(VDev *vdev)
         IPL_check(sdev->channel == 0, "non-zero channel requested");
         IPL_check(sdev->target <= vdev->config.scsi.max_target, "target# high");
         IPL_check(sdev->lun <= vdev->config.scsi.max_lun, "LUN# high");
-        return;
+        return 0;
     }
 
     for (target = 0; target <= vdev->config.scsi.max_target; target++) {
@@ -247,18 +252,20 @@ static void virtio_scsi_locate_device(VDev *vdev)
              */
             sdev->lun = r->lun[0].v16[0]; /* it's returned this way */
             debug_print_int("Have to use LUN", sdev->lun);
-            return; /* we have to use this device */
+            return 0; /* we have to use this device */
         }
         for (i = 0; i < luns; i++) {
             if (r->lun[i].v64) {
                 /* Look for non-zero LUN - we have where to choose from */
                 sdev->lun = r->lun[i].v16[0];
                 debug_print_int("Will use LUN", sdev->lun);
-                return; /* we have found a device */
+                return 0; /* we have found a device */
             }
         }
     }
-    panic("\n! Cannot locate virtio-scsi device !\n");
+
+    sclp_print("Warning: Could not locate a usable virtio-scsi device\n");
+    return -ENODEV;
 }
 
 int virtio_scsi_read_many(VDev *vdev,
@@ -322,17 +329,20 @@ static void scsi_parse_capacity_report(void *data,
     }
 }
 
-void virtio_scsi_setup(VDev *vdev)
+int virtio_scsi_setup(VDev *vdev)
 {
     int retry_test_unit_ready = 3;
     uint8_t data[256];
     uint32_t data_size = sizeof(data);
     ScsiInquiryEvpdPages *evpd = &scsi_inquiry_evpd_pages_response;
     ScsiInquiryEvpdBl *evpd_bl = &scsi_inquiry_evpd_bl_response;
-    int i;
+    int i, ret;
 
     vdev->scsi_device = &default_scsi_device;
-    virtio_scsi_locate_device(vdev);
+    ret = virtio_scsi_locate_device(vdev);
+    if (ret < 0) {
+        return ret;
+    }
 
     /* We have to "ping" the device before it becomes readable */
     while (!scsi_test_unit_ready(vdev)) {
@@ -417,4 +427,6 @@ void virtio_scsi_setup(VDev *vdev)
     }
     scsi_parse_capacity_report(data, &vdev->scsi_last_block,
                                (uint32_t *) &vdev->scsi_block_size);
+
+    return 0;
 }

pc-bios/s390-ccw/virtio-scsi.h

@@ -67,7 +67,7 @@ static inline bool virtio_scsi_response_ok(const VirtioScsiCmdResp *r)
         return r->response == VIRTIO_SCSI_S_OK && r->status == CDB_STATUS_GOOD;
 }
 
-void virtio_scsi_setup(VDev *vdev);
+int virtio_scsi_setup(VDev *vdev);
 int virtio_scsi_read_many(VDev *vdev,
                           ulong sector, void *load_addr, int sec_num);