xen/hvc: Fix error cases around HVM_PARAM_CONSOLE_PFN

We weren't resetting the parameter to be passed in to a
known default. Nor were we checking the return value of
hvm_get_parameter.

CC: stable@kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index afc7fc2..3277f0e 100644 (file)
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -219,7 +219,8 @@ static int xen_hvm_console_init(void)
        if (r < 0)
                goto err;
        info->evtchn = v;
        if (r < 0)
                goto err;
        info->evtchn = v;

-       hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
+       v = 0;
+       r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);

        if (r < 0)
                goto err;
        mfn = v;
        if (r < 0)
                goto err;
        mfn = v;