usb: Move clearing of queue on halt to the core

hcds which queue up more then one packet at once (uhci, ehci and xhci),
must clear the queue after an error which has caused the queue to halt.

Currently this is handled as a special case inside the hcd code, this
patch instead adds an USB_RET_REMOVE_FROM_QUEUE packet result code, teaches
the 3 hcds about this and moves the clearing of the queue on a halt into
the USB core.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/usb.h

@@ -45,6 +45,7 @@
 #define USB_RET_IOERROR           (-5)
 #define USB_RET_ASYNC             (-6)
 #define USB_RET_ADD_TO_QUEUE      (-7)
+#define USB_RET_REMOVE_FROM_QUEUE (-8)
 
 #define USB_SPEED_LOW   0
 #define USB_SPEED_FULL  1

hw/usb/core.c

@@ -442,8 +442,14 @@ void usb_packet_complete(USBDevice *dev, USBPacket *p)
     usb_packet_check_state(p, USB_PACKET_ASYNC);
     usb_packet_complete_one(dev, p);
 
-    while (!ep->halted && !QTAILQ_EMPTY(&ep->queue)) {
+    while (!QTAILQ_EMPTY(&ep->queue)) {
         p = QTAILQ_FIRST(&ep->queue);
+        if (ep->halted) {
+            /* Empty the queue on a halt */
+            p->result = USB_RET_REMOVE_FROM_QUEUE;
+            dev->port->ops->complete(dev->port, p);
+            continue;
+        }
         if (p->state == USB_PACKET_ASYNC) {
             break;
         }

hw/usb/hcd-ehci.c

@@ -1457,8 +1457,15 @@ static void ehci_async_complete_packet(USBPort *port, USBPacket *packet)
     }
 
     p = container_of(packet, EHCIPacket, packet);
-    trace_usb_ehci_packet_action(p->queue, p, "wakeup");
     assert(p->async == EHCI_ASYNC_INFLIGHT);
+
+    if (packet->result == USB_RET_REMOVE_FROM_QUEUE) {
+        trace_usb_ehci_packet_action(p->queue, p, "remove");
+        ehci_free_packet(p);
+        return;
+    }
+
+    trace_usb_ehci_packet_action(p->queue, p, "wakeup");
     p->async = EHCI_ASYNC_FINISHED;
     p->usb_status = packet->result;
 
@@ -2216,19 +2223,6 @@ static int ehci_state_writeback(EHCIQueue *q)
      * bit is clear.
      */
     if (q->qh.token & QTD_TOKEN_HALT) {
-        /*
-         * We should not do any further processing on a halted queue!
-         * This is esp. important for bulk endpoints with pipelining enabled
-         * (redirection to a real USB device), where we must cancel all the
-         * transfers after this one so that:
-         * 1) If they've completed already, they are not processed further
-         *    causing more stalls, originating from the same failed transfer
-         * 2) If still in flight, they are cancelled before the guest does
-         *    a clear stall, otherwise the guest and device can loose sync!
-         */
-        while ((p = QTAILQ_FIRST(&q->packets)) != NULL) {
-            ehci_free_packet(p);
-        }
         ehci_set_state(q->ehci, q->async, EST_HORIZONTALQH);
         again = 1;
     } else {

hw/usb/hcd-uhci.c

@@ -744,22 +744,6 @@ static int uhci_complete_td(UHCIState *s, UHCI_TD *td, UHCIAsync *async, uint32_
     return TD_RESULT_COMPLETE;
 
 out:
-    /*
-     * We should not do any further processing on a queue with errors!
-     * This is esp. important for bulk endpoints with pipelining enabled
-     * (redirection to a real USB device), where we must cancel all the
-     * transfers after this one so that:
-     * 1) If they've completed already, they are not processed further
-     *    causing more stalls, originating from the same failed transfer
-     * 2) If still in flight, they are cancelled before the guest does
-     *    a clear stall, otherwise the guest and device can loose sync!
-     */
-    while (!QTAILQ_EMPTY(&async->queue->asyncs)) {
-        UHCIAsync *as = QTAILQ_FIRST(&async->queue->asyncs);
-        uhci_async_unlink(as);
-        uhci_async_cancel(as);
-    }
-
     switch(ret) {
     case USB_RET_STALL:
         td->ctrl |= TD_CTRL_STALL;
@@ -918,6 +902,12 @@ static void uhci_async_complete(USBPort *port, USBPacket *packet)
     UHCIAsync *async = container_of(packet, UHCIAsync, packet);
     UHCIState *s = async->queue->uhci;
 
+    if (packet->result == USB_RET_REMOVE_FROM_QUEUE) {
+        uhci_async_unlink(async);
+        uhci_async_cancel(async);
+        return;
+    }
+
     if (async->isoc) {
         UHCI_TD td;
         uint32_t link = async->td;

hw/usb/hcd-xhci.c

@@ -2839,6 +2839,10 @@ static void xhci_complete(USBPort *port, USBPacket *packet)
 {
     XHCITransfer *xfer = container_of(packet, XHCITransfer, packet);
 
+    if (packet->result == USB_RET_REMOVE_FROM_QUEUE) {
+        xhci_ep_nuke_one_xfer(xfer);
+        return;
+    }
     xhci_complete_packet(xfer, packet->result);
     xhci_kick_ep(xfer->xhci, xfer->slotid, xfer->epid);
 }