SWITCH_FUNCTION is only allowed in TRANSFER state
(See 4.8 "Card State Transition Table).

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/sd/sd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/sd/sd.c b/hw/sd/sd.c
index fce99d655d..3b885ba8a0 100644
--- a/hw/sd/sd.c
+++ b/hw/sd/sd.c
@@ -1196,6 +1196,10 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, SDRequest req)
         if (sd->mode != sd_data_transfer_mode) {
             return sd_invalid_mode_for_cmd(sd, req);
         }
+        if (sd->state != sd_transfer_state) {
+            return sd_invalid_state_for_cmd(sd, req);
+        }
+
         sd_function_switch(sd, req.arg);
         sd->state = sd_sendingdata_state;
         sd->data_start = 0;
-- 
2.41.0