diff options
| -rw-r--r-- | drivers/tty/hvc/hvc_xen.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c index 3277f0eec4a..944eaeb8e0c 100644 --- a/drivers/tty/hvc/hvc_xen.c +++ b/drivers/tty/hvc/hvc_xen.c @@ -214,14 +214,19 @@ static int xen_hvm_console_init(void) /* already configured */ if (info->intf != NULL) return 0; - + /* + * If the toolstack (or the hypervisor) hasn't set these values, the + * default value is 0. Even though mfn = 0 and evtchn = 0 are + * theoretically correct values, in practice they never are and they + * mean that a legacy toolstack hasn't initialized the pv console correctly. + */ r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v); - if (r < 0) + if (r < 0 || v == 0) goto err; info->evtchn = v; v = 0; r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v); - if (r < 0) + if (r < 0 || v == 0) goto err; mfn = v; info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE); |