/* $Id: VUSBReadAhead.cpp 56292 2015-06-09 14:20:46Z vboxsync $ */ /** @file * Virtual USB - Read-ahead buffering for periodic endpoints. */ /* * Copyright (C) 2006-2015 Oracle Corporation * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. */ /******************************************************************************* * Header Files * *******************************************************************************/ #define LOG_GROUP LOG_GROUP_DRV_VUSB #include #include #include #include #include #include #include #include #include #include #include #include #include "VUSBInternal.h" /******************************************************************************* * Structures and Typedefs * *******************************************************************************/ /** * VUSB Readahead instance data. */ typedef struct VUSBREADAHEADINT { /** Pointer to the device which the thread is for. */ PVUSBDEV pDev; /** Pointer to the pipe which the thread is servicing. */ PVUSBPIPE pPipe; /** A flag indicating a high-speed (vs. low/full-speed) endpoint. */ bool fHighSpeed; /** A flag telling the thread to terminate. */ volatile bool fTerminate; /** Maximum number of URBs to submit. */ uint32_t cUrbsMax; /** The periodic read-ahead buffer thread. */ RTTHREAD hReadAheadThread; /** Pointer to the first buffered URB. */ PVUSBURB pBuffUrbHead; /** Pointer to the last buffered URB. */ PVUSBURB pBuffUrbTail; /** Count of URBs in read-ahead buffer. */ uint32_t cBuffered; /** Count of URBs submitted for read-ahead but not yet reaped. */ uint32_t cSubmitted; /** Critical section to serialize access the buffered URB list. */ RTCRITSECT CritSectBuffUrbList; } VUSBREADAHEADINT, *PVUSBREADAHEADINT; /******************************************************************************* * Implementation * *******************************************************************************/ static PVUSBURB vusbDevNewIsocUrb(PVUSBDEV pDev, unsigned uEndPt, unsigned uInterval, unsigned uPktSize) { PVUSBURB pUrb; unsigned cPackets = 0; uint32_t cbTotal = 0; unsigned uNextIndex = 0; Assert(pDev); Assert(uEndPt); Assert(uInterval); Assert(uPktSize); /* Calculate the amount of data needed, taking the endpoint's bInterval into account */ for (unsigned i = 0; i < 8; ++i) { if (i == uNextIndex) { cbTotal += uPktSize; cPackets++; uNextIndex += uInterval; } } Assert(cbTotal <= 24576); // @todo: What do we do if cPackets is 0? /* * Allocate and initialize the URB. */ Assert(pDev->u8Address != VUSB_INVALID_ADDRESS); PVUSBROOTHUB pRh = vusbDevGetRh(pDev); if (!pRh) /* can happen during disconnect */ return NULL; pUrb = vusbRhNewUrb(pRh, pDev->u8Address, cbTotal, 1); if (!pUrb) /* not much we can do here... */ return NULL; pUrb->enmType = VUSBXFERTYPE_ISOC; pUrb->EndPt = uEndPt; pUrb->enmDir = VUSBDIRECTION_IN; pUrb->fShortNotOk = false; pUrb->enmStatus = VUSBSTATUS_OK; pUrb->Hci.EdAddr = 0; pUrb->Hci.fUnlinked = false; // @todo: fill in the rest? The Hci member is not relevant #ifdef LOG_ENABLED static unsigned s_iSerial = 0; s_iSerial = (s_iSerial + 1) % 10000; RTStrAPrintf(&pUrb->pszDesc, "URB %p prab<%04d", pUrb, s_iSerial); // prab = Periodic Read-Ahead Buffer #endif /* Set up the individual packets, again with bInterval in mind */ pUrb->cIsocPkts = 8; unsigned off = 0; uNextIndex = 0; for (unsigned i = 0; i < 8; i++) { pUrb->aIsocPkts[i].enmStatus = VUSBSTATUS_NOT_ACCESSED; pUrb->aIsocPkts[i].off = off; if (i == uNextIndex) // skip unused packets { pUrb->aIsocPkts[i].cb = uPktSize; off += uPktSize; uNextIndex += uInterval; } else pUrb->aIsocPkts[i].cb = 0; } Assert(off == cbTotal); return pUrb; } /** * Thread function for performing read-ahead buffering of periodic input. * * This thread keeps a buffer (queue) filled with data read from a periodic * input endpoint. * * The problem: In the EHCI emulation, there is a very short period between the * time when the guest can schedule a request and the time when it expects the results. * This leads to many dropped URBs because by the time we get the data from the host, * the guest already gave up and moved on. * * The solution: For periodic transfers, we know the worst-case bandwidth. We can * read ahead and buffer a few milliseconds worth of data. That way data is available * by the time the guest asks for it and we can deliver it immediately. * * @returns success indicator. * @param Thread This thread. * @param pvUser Pointer to a VUSBREADAHEADARGS structure. */ static DECLCALLBACK(int) vusbDevReadAheadThread(RTTHREAD Thread, void *pvUser) { PVUSBREADAHEADINT pThis = (PVUSBREADAHEADINT)pvUser; PVUSBPIPE pPipe; PCVUSBDESCENDPOINT pDesc; PVUSBURB pUrb; int rc = VINF_SUCCESS; unsigned max_pkt_size, mult, interval; LogFlow(("vusb: periodic read-ahead buffer thread started\n")); Assert(pThis); Assert(pThis->pPipe && pThis->pDev); pPipe = pThis->pPipe; pDesc = &pPipe->in->Core; Assert(pDesc); Assert(!pThis->cSubmitted && !pThis->cBuffered); /* Figure out the maximum bandwidth we might need */ if (pThis->fHighSpeed) { /* High-speed endpoint */ Assert((pDesc->wMaxPacketSize & 0x1fff) == pDesc->wMaxPacketSize); Assert(pDesc->bInterval <= 16); interval = pDesc->bInterval ? 1 << (pDesc->bInterval - 1) : 1; max_pkt_size = pDesc->wMaxPacketSize & 0x7ff; mult = ((pDesc->wMaxPacketSize & 0x1800) >> 11) + 1; } else { /* Full- or low-speed endpoint */ Assert((pDesc->wMaxPacketSize & 0x7ff) == pDesc->wMaxPacketSize); interval = pDesc->bInterval; max_pkt_size = pDesc->wMaxPacketSize; mult = 1; } Log(("vusb: interval=%u, max pkt size=%u, multiplier=%u\n", interval, max_pkt_size, mult)); /* * Submit new URBs in a loop unless the buffer is too full (paused VM etc.). Note that we only * queue the URBs here, they are reaped on a different thread. */ while (!pThis->fTerminate) { while (pThis->cSubmitted < pThis->cUrbsMax && pThis->cBuffered < pThis->cUrbsMax) { pUrb = vusbDevNewIsocUrb(pThis->pDev, pDesc->bEndpointAddress & 0xF, interval, max_pkt_size * mult); if (!pUrb) { /* Happens if device was unplugged. */ Log(("vusb: read-ahead thread failed to allocate new URB; exiting\n")); vusbReadAheadStop(pThis); break; } Assert(pUrb->enmState == VUSBURBSTATE_ALLOCATED); // @todo: at the moment we abuse the Hci.pNext member (which is otherwise entirely unused!) pUrb->Hci.pNext = (PVUSBURB)pvUser; pUrb->enmState = VUSBURBSTATE_IN_FLIGHT; rc = vusbUrbQueueAsyncRh(pUrb); if (RT_FAILURE(rc)) { /* Happens if device was unplugged. */ Log(("vusb: read-ahead thread failed to queue URB with %Rrc; exiting\n", rc)); pThis->cUrbsMax = pThis->cSubmitted; pUrb->VUsb.pfnFree(pUrb); break; } else ASMAtomicIncU32(&pThis->cSubmitted); } RTThreadSleep(1); } LogFlow(("vusb: periodic read-ahead buffer thread exiting\n")); /* wait until there are no more submitted packets */ while (pThis->cSubmitted > 0) { Log2(("vusbDevReadAheadThread: still %u packets submitted, waiting before terminating...\n", pThis->cSubmitted)); RTThreadSleep(1); } RTCritSectEnter(&pThis->CritSectBuffUrbList); /* * Free all still buffered URBs because another endpoint with a different packet size * and complete different data formats might be served later. */ while (pThis->pBuffUrbHead) { PVUSBURB pBufferedUrb = pThis->pBuffUrbHead; pThis->pBuffUrbHead = pBufferedUrb->Hci.pNext; pBufferedUrb->VUsb.pfnFree(pBufferedUrb); } RTCritSectLeave(&pThis->CritSectBuffUrbList); RTCritSectDelete(&pThis->CritSectBuffUrbList); RTMemTmpFree(pThis); return rc; } /** * Completes a read-ahead URB. This function does *not* free the URB but puts * it on a queue instead. The URB is only freed when the guest asks for the data * (by reading on the buffered pipe) or when the pipe/device is torn down. */ void vusbUrbCompletionReadAhead(PVUSBURB pUrb) { Assert(pUrb); Assert(pUrb->Hci.pNext); PVUSBREADAHEADINT pThis = (PVUSBREADAHEADINT)pUrb->Hci.pNext; PVUSBPIPE pPipe = pThis->pPipe; Assert(pPipe); RTCritSectEnter(&pThis->CritSectBuffUrbList); pUrb->Hci.pNext = NULL; // @todo: use a more suitable field if (pThis->pBuffUrbHead == NULL) { // The queue is empty, this is easy Assert(!pThis->pBuffUrbTail); pThis->pBuffUrbTail = pThis->pBuffUrbHead = pUrb; } else { // Some URBs are queued already Assert(pThis->pBuffUrbTail); Assert(!pThis->pBuffUrbTail->Hci.pNext); pThis->pBuffUrbTail = pThis->pBuffUrbTail->Hci.pNext = pUrb; } ASMAtomicDecU32(&pThis->cSubmitted); ++pThis->cBuffered; RTCritSectLeave(&pThis->CritSectBuffUrbList); } /** * Process a submit of an input URB on a pipe with read-ahead buffering. Instead * of passing the URB to the proxy, we use previously read data stored in the * read-ahead buffer, immediately complete the input URB and free the buffered URB. * * @param pUrb The URB submitted by HC * @param hReadAhead The read-ahead buffering instance * * @return int Status code */ int vusbUrbSubmitBufferedRead(PVUSBURB pUrb, VUSBREADAHEAD hReadAhead) { PVUSBREADAHEADINT pThis = hReadAhead; PVUSBURB pBufferedUrb; Assert(pUrb && pThis); RTCritSectEnter(&pThis->CritSectBuffUrbList); pBufferedUrb = pThis->pBuffUrbHead; if (pBufferedUrb) { unsigned cbTotal; // There's a URB available in the read-ahead buffer; use it pThis->pBuffUrbHead = pBufferedUrb->Hci.pNext; if (pThis->pBuffUrbHead == NULL) pThis->pBuffUrbTail = NULL; --pThis->cBuffered; RTCritSectLeave(&pThis->CritSectBuffUrbList); // Make sure the buffered URB is what we expect Assert(pUrb->enmType == pBufferedUrb->enmType); Assert(pUrb->EndPt == pBufferedUrb->EndPt); Assert(pUrb->enmDir == pBufferedUrb->enmDir); pUrb->enmState = VUSBURBSTATE_REAPED; pUrb->enmStatus = pBufferedUrb->enmStatus; cbTotal = 0; // Copy status and data received from the device for (unsigned i = 0; i < pUrb->cIsocPkts; ++i) { unsigned off, len; off = pBufferedUrb->aIsocPkts[i].off; len = pBufferedUrb->aIsocPkts[i].cb; pUrb->aIsocPkts[i].cb = len; pUrb->aIsocPkts[i].off = off; pUrb->aIsocPkts[i].enmStatus = pBufferedUrb->aIsocPkts[i].enmStatus; cbTotal += len; Assert(pUrb->VUsb.cbDataAllocated >= cbTotal); memcpy(&pUrb->abData[off], &pBufferedUrb->abData[off], len); } // Give back the data to the HC right away and then free the buffered URB vusbUrbCompletionRh(pUrb); // This assertion is wrong as the URB could be re-allocated in the meantime by the EMT (race) // Assert(pUrb->enmState == VUSBURBSTATE_FREE); Assert(pBufferedUrb->enmState == VUSBURBSTATE_REAPED); LogFlow(("%s: vusbUrbSubmitBufferedRead: Freeing buffered URB\n", pBufferedUrb->pszDesc)); pBufferedUrb->VUsb.pfnFree(pBufferedUrb); // This assertion is wrong as the URB could be re-allocated in the meantime by the EMT (race) // Assert(pBufferedUrb->enmState == VUSBURBSTATE_FREE); } else { RTCritSectLeave(&pThis->CritSectBuffUrbList); // No URB on hand. Either we exhausted the buffer (shouldn't happen!) or the guest simply // asked for data too soon. Pretend that the device didn't deliver any data. pUrb->enmState = VUSBURBSTATE_REAPED; pUrb->enmStatus = VUSBSTATUS_DATA_UNDERRUN; for (unsigned i = 0; i < pUrb->cIsocPkts; ++i) { pUrb->aIsocPkts[i].cb = 0; pUrb->aIsocPkts[i].enmStatus = VUSBSTATUS_NOT_ACCESSED; } vusbUrbCompletionRh(pUrb); // This assertion is wrong as the URB could be re-allocated in the meantime by the EMT (race) // Assert(pUrb->enmState == VUSBURBSTATE_FREE); LogFlow(("vusbUrbSubmitBufferedRead: No buffered URB available!\n")); } return VINF_SUCCESS; } /* Read-ahead start/stop functions, used primarily to keep the PVUSBREADAHEADARGS struct private to this module. */ VUSBREADAHEAD vusbReadAheadStart(PVUSBDEV pDev, PVUSBPIPE pPipe) { int rc; PVUSBREADAHEADINT pThis = (PVUSBREADAHEADINT)RTMemTmpAlloc(sizeof(VUSBREADAHEADINT)); if (pThis) { PVUSBROOTHUB pRh = vusbDevGetRh(pDev); pThis->pDev = pDev; pThis->pPipe = pPipe; pThis->fTerminate = false; pThis->fHighSpeed = pRh && ((pRh->fHcVersions & VUSB_STDVER_20) != 0); pThis->cUrbsMax = 120; pThis->pBuffUrbHead = NULL; pThis->pBuffUrbTail = NULL; pThis->cBuffered = 0; pThis->cSubmitted = 0; rc = RTCritSectInit(&pThis->CritSectBuffUrbList); if (RT_SUCCESS(rc)) { if (pThis->fHighSpeed) rc = RTThreadCreate(&pThis->hReadAheadThread, vusbDevReadAheadThread, pThis, 0, RTTHREADTYPE_IO, 0 /* fFlags */, "USBISOC"); else rc = VERR_VUSB_DEVICE_NOT_ATTACHED; // No buffering for low/full-speed devices at the moment, needs testing. if (RT_SUCCESS(rc)) { Log(("vusb: created isochronous read-ahead thread\n")); return pThis; } else Log(("vusb: isochronous read-ahead thread creation failed, rc=%d\n", rc)); rc = RTCritSectDelete(&pThis->CritSectBuffUrbList); AssertRC(rc); } RTMemTmpFree(pThis); } /* If thread creation failed for any reason, simply fall back to standard processing. */ return NULL; } void vusbReadAheadStop(VUSBREADAHEAD hReadAhead) { PVUSBREADAHEADINT pThis = hReadAhead; Log(("vusb: terminating read-ahead thread for endpoint\n")); ASMAtomicXchgBool(&pThis->fTerminate, true); } /* * Local Variables: * mode: c * c-file-style: "bsd" * c-basic-offset: 4 * tab-width: 4 * indent-tabs-mode: s * End: */