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>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index afc7fc27aa52..3277f0eec4a7 100644
--- 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;
-        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;