From ccee80c68db14b3e965582a19393992b5c2b97f4 Mon Sep 17 00:00:00 2001 From: Anthony PERARD Date: Wed, 14 Oct 2020 11:41:06 +0100 Subject: [PATCH] usb/hcd-ehci: Fix error handling on missing device for iTD The EHCI Host Controller emulation attempt to locate the device associated with a periodic isochronous transfer description (iTD) and when this fail the host controller is reset. But according the EHCI spec 1.0 section 5.15.2.4 Host System Error, the host controller is supposed to reset itself only when it failed to communicate with the Host (Operating System), like when there's an error on the PCI bus. If a transaction fails, there's nothing in the spec that say to reset the host controller. This patch rework the error path so that the host controller can keep working when the OS setup a bogus transaction, it also revert to the behavior of the EHCI emulation to before commits: e94682f1fe ("ehci: check device is not NULL before calling usb_ep_get()") 7011baece2 ("usb: remove unnecessary NULL device check from usb_ep_get()") The issue has been found while trying to passthrough a USB device to a Windows Server 2012 Xen guest via "usb-ehci", which prevent the USB device from working in Windows. ("usb-ehci" alone works, windows only setup this weird periodic iTD to device 127 endpoint 15 when the USB device is passthrough.) Signed-off-by: Anthony PERARD Message-id: 20201014104106.2962640-1-anthony.perard@citrix.com Signed-off-by: Gerd Hoffmann --- hw/usb/hcd-ehci.c | 35 ++++++++++++++++++----------------- 1 file changed, 18 insertions(+), 17 deletions(-) diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c index 2b995443fb..ae7f20c502 100644 --- a/hw/usb/hcd-ehci.c +++ b/hw/usb/hcd-ehci.c @@ -1447,24 +1447,25 @@ static int ehci_process_itd(EHCIState *ehci, dev = ehci_find_device(ehci, devaddr); if (dev == NULL) { ehci_trace_guest_bug(ehci, "no device found"); - qemu_sglist_destroy(&ehci->isgl); - return -1; - } - pid = dir ? USB_TOKEN_IN : USB_TOKEN_OUT; - ep = usb_ep_get(dev, pid, endp); - if (ep && ep->type == USB_ENDPOINT_XFER_ISOC) { - usb_packet_setup(&ehci->ipacket, pid, ep, 0, addr, false, - (itd->transact[i] & ITD_XACT_IOC) != 0); - if (usb_packet_map(&ehci->ipacket, &ehci->isgl)) { - qemu_sglist_destroy(&ehci->isgl); - return -1; - } - usb_handle_packet(dev, &ehci->ipacket); - usb_packet_unmap(&ehci->ipacket, &ehci->isgl); - } else { - DPRINTF("ISOCH: attempt to addess non-iso endpoint\n"); - ehci->ipacket.status = USB_RET_NAK; + ehci->ipacket.status = USB_RET_NODEV; ehci->ipacket.actual_length = 0; + } else { + pid = dir ? USB_TOKEN_IN : USB_TOKEN_OUT; + ep = usb_ep_get(dev, pid, endp); + if (ep && ep->type == USB_ENDPOINT_XFER_ISOC) { + usb_packet_setup(&ehci->ipacket, pid, ep, 0, addr, false, + (itd->transact[i] & ITD_XACT_IOC) != 0); + if (usb_packet_map(&ehci->ipacket, &ehci->isgl)) { + qemu_sglist_destroy(&ehci->isgl); + return -1; + } + usb_handle_packet(dev, &ehci->ipacket); + usb_packet_unmap(&ehci->ipacket, &ehci->isgl); + } else { + DPRINTF("ISOCH: attempt to addess non-iso endpoint\n"); + ehci->ipacket.status = USB_RET_NAK; + ehci->ipacket.actual_length = 0; + } } qemu_sglist_destroy(&ehci->isgl);