[PATCH 6/6] xhci: move sanity checks

[Gerd Hoffmann <kraxel@redhat.com>]

The v variable goes negative for reg < 0x20.  Reorder the code
to first sanity check then calculate v and assign intr to make
sanity checkers happy.

Buglink: https://bugs.launchpad.net/qemu/+bug/1902112
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/hcd-xhci.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index d00bb0141dac..6dfb17cbe915 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -3010,14 +3010,17 @@ static void xhci_runtime_write(void *ptr, hwaddr reg,
                                uint64_t val, unsigned size)
 {
     XHCIState *xhci = ptr;
-    int v = (reg - 0x20) / 0x20;
-    XHCIInterrupter *intr = &xhci->intr[v];
+    XHCIInterrupter *intr;
+    int v;
+
     trace_usb_xhci_runtime_write(reg, val);
 
     if (reg < 0x20) {
         trace_usb_xhci_unimplemented("runtime write", reg);
         return;
     }
+    v = (reg - 0x20) / 0x20;
+    intr = &xhci->intr[v];
 
     switch (reg & 0x1f) {
     case 0x00: /* IMAN */
-- 
2.27.0