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authorGerd Hoffmann <kraxel@redhat.com>2017-02-03 07:51:45 +0100
committerGerd Hoffmann <kraxel@redhat.com>2017-02-06 12:12:26 +0100
commit7da76e12cc5cc902dda4c168d8d608fd4e61cbc5 (patch)
treec24af1674087722eecc36e22725c2e3f6fd058c7 /hw/usb/hcd-xhci.c
parentc7dfbf322595ded4e70b626bf83158a9f3807c6a (diff)
xhci: fix event queue IRQ handling
The qemu xhci emulation doesn't handle the ERDP_EHB flag correctly. When the host adapter queues a new event the ERDP_EHB flag is set. The flag is cleared (via w1c) by the guest when it updates the ERDP (event ring dequeue pointer) register to notify the host adapter which events it has fetched. An IRQ must be raised in case the ERDP_EHB flag flips from clear to set. If the flag is set already (which implies there are events queued up which are not yet processed by the guest) xhci must *not* raise a IRQ. Qemu got that wrong and raised an IRQ on every event, thereby generating spurious interrupts in case we've queued events faster than the guest processed them. This patch fixes that. With that change in place we also have to check ERDP updates, to see whenever the guest has fetched all queued events. In case there are still pending events set ERDP_EHB and raise an IRQ again, to make sure the events don't linger unseen forever. The linux kernel driver and the microsoft windows driver (shipped with win8+) can deal with the spurious interrupts without problems. The renesas windows driver (v2.1.39) which can be used on older windows versions is quite upset though. It does spurious ERDP updates now and then (not every time, seems we must hit a race window for this to happen), which in turn makes the qemu xhci emulation think the event ring is full. Things go south from here ... tl;dr: This is the "fix xhci on win7" patch. Cc: M.Cerveny@computer.org Cc: 1373228@bugs.launchpad.net Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Message-id: 1486104705-13761-1-git-send-email-kraxel@redhat.com
Diffstat (limited to 'hw/usb/hcd-xhci.c')
-rw-r--r--hw/usb/hcd-xhci.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 1878dad2ce..54b3901c8c 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -789,11 +789,15 @@ static void xhci_msix_update(XHCIState *xhci, int v)
static void xhci_intr_raise(XHCIState *xhci, int v)
{
PCIDevice *pci_dev = PCI_DEVICE(xhci);
+ bool pending = (xhci->intr[v].erdp_low & ERDP_EHB);
xhci->intr[v].erdp_low |= ERDP_EHB;
xhci->intr[v].iman |= IMAN_IP;
xhci->usbsts |= USBSTS_EINT;
+ if (pending) {
+ return;
+ }
if (!(xhci->intr[v].iman & IMAN_IE)) {
return;
}
@@ -3352,6 +3356,15 @@ static void xhci_runtime_write(void *ptr, hwaddr reg,
intr->erdp_low &= ~ERDP_EHB;
}
intr->erdp_low = (val & ~ERDP_EHB) | (intr->erdp_low & ERDP_EHB);
+ if (val & ERDP_EHB) {
+ dma_addr_t erdp = xhci_addr64(intr->erdp_low, intr->erdp_high);
+ unsigned int dp_idx = (erdp - intr->er_start) / TRB_SIZE;
+ if (erdp >= intr->er_start &&
+ erdp < (intr->er_start + TRB_SIZE * intr->er_size) &&
+ dp_idx != intr->er_ep_idx) {
+ xhci_intr_raise(xhci, v);
+ }
+ }
break;
case 0x1c: /* ERDP high */
intr->erdp_high = val;