[Qemu-devel] [PATCH 05/10] xhci: emulate intr endpoint intervals correctly

[Gerd Hoffmann <kraxel@redhat.com>]

Respect the interval for interrupt endpoints, so we don't finish
transfers as fast as possible but at the rate configured by the guest.

Fixes guest deadlocks triggered by interrupt storms.

Cc:
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/hcd-xhci.c | 44 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 37 insertions(+), 7 deletions(-)

diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 3826979..2e2eb55 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -355,6 +355,7 @@ typedef struct XHCITransfer {
     unsigned int streamid;
     bool in_xfer;
     bool iso_xfer;
+    bool timed_xfer;
 
     unsigned int trb_count;
     unsigned int trb_alloced;
@@ -1820,6 +1821,7 @@ static int xhci_fire_ctl_transfer(XHCIState *xhci, XHCITransfer *xfer)
 
     xfer->in_xfer = bmRequestType & USB_DIR_IN;
     xfer->iso_xfer = false;
+    xfer->timed_xfer = false;
 
     if (xhci_setup_packet(xfer) < 0) {
         return -1;
@@ -1835,6 +1837,17 @@ static int xhci_fire_ctl_transfer(XHCIState *xhci, XHCITransfer *xfer)
     return 0;
 }
 
+static void xhci_calc_intr_kick(XHCIState *xhci, XHCITransfer *xfer,
+                                XHCIEPContext *epctx, uint64_t mfindex)
+{
+    uint64_t asap = ((mfindex + epctx->interval - 1) &
+                     ~(epctx->interval-1));
+    uint64_t kick = epctx->mfindex_last + epctx->interval;
+
+    assert(epctx->interval != 0);
+    xfer->mfindex_kick = MAX(asap, kick);
+}
+
 static void xhci_calc_iso_kick(XHCIState *xhci, XHCITransfer *xfer,
                                XHCIEPContext *epctx, uint64_t mfindex)
 {
@@ -1857,8 +1870,8 @@ static void xhci_calc_iso_kick(XHCIState *xhci, XHCITransfer *xfer,
     }
 }
 
-static void xhci_check_iso_kick(XHCIState *xhci, XHCITransfer *xfer,
-                                XHCIEPContext *epctx, uint64_t mfindex)
+static void xhci_check_intr_iso_kick(XHCIState *xhci, XHCITransfer *xfer,
+                                     XHCIEPContext *epctx, uint64_t mfindex)
 {
     if (xfer->mfindex_kick > mfindex) {
         timer_mod(epctx->kick_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
@@ -1883,18 +1896,30 @@ static int xhci_submit(XHCIState *xhci, XHCITransfer *xfer, XHCIEPContext *epctx
     switch(epctx->type) {
     case ET_INTR_OUT:
     case ET_INTR_IN:
+        xfer->pkts = 0;
+        xfer->iso_xfer = false;
+        xfer->timed_xfer = true;
+        mfindex = xhci_mfindex_get(xhci);
+        xhci_calc_intr_kick(xhci, xfer, epctx, mfindex);
+        xhci_check_intr_iso_kick(xhci, xfer, epctx, mfindex);
+        if (xfer->running_retry) {
+            return -1;
+        }
+        break;
     case ET_BULK_OUT:
     case ET_BULK_IN:
         xfer->pkts = 0;
         xfer->iso_xfer = false;
+        xfer->timed_xfer = false;
         break;
     case ET_ISO_OUT:
     case ET_ISO_IN:
         xfer->pkts = 1;
         xfer->iso_xfer = true;
+        xfer->timed_xfer = true;
         mfindex = xhci_mfindex_get(xhci);
         xhci_calc_iso_kick(xhci, xfer, epctx, mfindex);
-        xhci_check_iso_kick(xhci, xfer, epctx, mfindex);
+        xhci_check_intr_iso_kick(xhci, xfer, epctx, mfindex);
         if (xfer->running_retry) {
             return -1;
         }
@@ -1955,13 +1980,18 @@ static void xhci_kick_ep(XHCIState *xhci, unsigned int slotid,
 
         trace_usb_xhci_xfer_retry(xfer);
         assert(xfer->running_retry);
-        if (xfer->iso_xfer) {
-            /* retry delayed iso transfer */
+        if (xfer->timed_xfer) {
+            /* time to kick the transfer? */
             mfindex = xhci_mfindex_get(xhci);
-            xhci_check_iso_kick(xhci, xfer, epctx, mfindex);
+            xhci_check_intr_iso_kick(xhci, xfer, epctx, mfindex);
             if (xfer->running_retry) {
                 return;
             }
+            xfer->timed_xfer = 0;
+            xfer->running_retry = 1;
+        }
+        if (xfer->iso_xfer) {
+            /* retry iso transfer */
             if (xhci_setup_packet(xfer) < 0) {
                 return;
             }
@@ -2047,7 +2077,7 @@ static void xhci_kick_ep(XHCIState *xhci, unsigned int slotid,
                 epctx->next_xfer = (epctx->next_xfer + 1) % TD_QUEUE;
                 ep = xfer->packet.ep;
             } else {
-                if (!xfer->iso_xfer) {
+                if (!xfer->timed_xfer) {
                     fprintf(stderr, "xhci: error firing data transfer\n");
                 }
             }
-- 
1.8.3.1