hw/ppc/spapr: Fix boot path of usb-host storage devices

When passing through an USB storage device to a pseries guest, it
is currently not possible to automatically boot from the device
if the "bootindex" property has been specified, too (e.g. when using
"-device nec-usb-xhci -device usb-host,hostbus=1,hostaddr=2,bootindex=0"
at the command line). The problem is that QEMU builds a device tree path
like "/pci@800000020000000/usb@0/usb-host@1" and passes it to SLOF
in the /chosen/qemu,boot-list property. SLOF, however, probes the
USB device, recognizes that it is a storage device and thus changes
its name to "storage", and additionally adds a child node for the
SCSI LUN, so the correct boot path in SLOF is something like
"/pci@800000020000000/usb@0/storage@1/disk@101000000000000" instead.
So when we detect an USB mass storage device with SCSI interface,
we've got to adjust the firmware boot-device path properly that
SLOF can automatically boot from the device.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1354177
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 13 insertions, 0 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 74419f82f0..f2edbd056d 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2198,6 +2198,19 @@ static char *spapr_get_fw_dev_path(FWPathProvider *p, BusState *bus,
         }
     }
 
+    /*
+     * SLOF probes the USB devices, and if it recognizes that the device is a
+     * storage device, it changes its name to "storage" instead of "usb-host",
+     * and additionally adds a child node for the SCSI LUN, so the correct
+     * boot path in SLOF is something like .../storage@1/disk@xxx" instead.
+     */
+    if (strcmp("usb-host", qdev_fw_name(dev)) == 0) {
+        USBDevice *usbdev = CAST(USBDevice, dev, TYPE_USB_DEVICE);
+        if (usb_host_dev_is_scsi_storage(usbdev)) {
+            return g_strdup_printf("storage@%s/disk", usbdev->port->path);
+        }
+    }
+
     if (phb) {
         /* Replace "pci" with "pci@800000020000000" */
         return g_strdup_printf("pci@%"PRIX64, phb->buid);