src/dev/virtio/fs9p.cc - public/gem5 - Git at Google

 /*
  * Copyright (c) 2014-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * property including but not limited to intellectual property relating
  * to a hardware implementation of the functionality of the software
  * licensed hereunder.  You may use the software subject to the license
  * terms below provided that you ensure that this notice is replicated
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Authors: Andreas Sandberg
  */

 #include "dev/virtio/fs9p.hh"

 #include <fcntl.h>
 #include <netdb.h>
 #include <netinet/in.h>
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <sys/un.h>
 #include <sys/wait.h>
 #include <unistd.h>

 #include <csignal>
 #include <fstream>

 #include "base/callback.hh"
 #include "base/output.hh"
 #include "debug/VIO9P.hh"
 #include "debug/VIO9PData.hh"
 #include "params/VirtIO9PBase.hh"
 #include "params/VirtIO9PDiod.hh"
 #include "params/VirtIO9PProxy.hh"
 #include "params/VirtIO9PSocket.hh"
 #include "sim/system.hh"

 struct P9MsgInfo {
     P9MsgInfo(P9MsgType _type, std::string _name)
         : type(_type), name(_name) {}

     P9MsgType type;
     std::string name;
 };

 typedef std::map<P9MsgType, P9MsgInfo> P9MsgInfoMap;

 #define P9MSG(type, name)                               \
     { (type), P9MsgInfo((type), "T" # name ) },         \
     { (type + 1), P9MsgInfo((type + 1), "R" # name ) }

 static const P9MsgInfoMap p9_msg_info {
     P9MSG(6, LERROR),
     P9MSG(8, STATFS),
     P9MSG(12, LOPEN),
     P9MSG(14, LCREATE),
     P9MSG(16, SYMLINK),
     P9MSG(18, MKNOD),
     P9MSG(20, RENAME),
     P9MSG(22, READLINK),
     P9MSG(24, GETATTR),
     P9MSG(26, SETATTR),
     P9MSG(30, XATTRWALK),
     P9MSG(32, XATTRCREATE),
     P9MSG(40, READDIR),
     P9MSG(50, FSYNC),
     P9MSG(52, LOCK),
     P9MSG(54, GETLOCK),
     P9MSG(70, LINK),
     P9MSG(72, MKDIR),
     P9MSG(74, RENAMEAT),
     P9MSG(76, UNLINKAT),
     P9MSG(100, VERSION),
     P9MSG(102, AUTH),
     P9MSG(104, ATTACH),
     P9MSG(106, ERROR),
     P9MSG(108, FLUSH),
     P9MSG(110, WALK),
     P9MSG(112, OPEN),
     P9MSG(114, CREATE),
     P9MSG(116, READ),
     P9MSG(118, WRITE),
     P9MSG(120, CLUNK),
     P9MSG(122, REMOVE),
     P9MSG(124, STAT),
     P9MSG(126, WSTAT),
 };

 #undef P9MSG

 VirtIO9PBase::VirtIO9PBase(Params *params)
     : VirtIODeviceBase(params, ID_9P,
                        sizeof(Config) + params->tag.size(),
                        F_MOUNT_TAG),
       queue(params->system->physProxy, params->queueSize, *this)
 {
     config.reset((Config *)
                  operator new(configSize));
     config->len = htov_legacy(params->tag.size());
     memcpy(config->tag, params->tag.c_str(), params->tag.size());

     registerQueue(queue);
 }


 VirtIO9PBase::~VirtIO9PBase()
 {
 }

 void
 VirtIO9PBase::readConfig(PacketPtr pkt, Addr cfgOffset)
 {
     readConfigBlob(pkt, cfgOffset, (uint8_t *)config.get());
 }

 void
 VirtIO9PBase::FSQueue::onNotifyDescriptor(VirtDescriptor *desc)
 {
     DPRINTF(VIO9P, "Got input data descriptor (len: %i)\n", desc->size());
     DPRINTF(VIO9P, "\tPending transactions: %i\n", parent.pendingTransactions.size());

     P9MsgHeader header;
     desc->chainRead(0, (uint8_t *)&header, sizeof(header));
     header = p9toh(header);

     uint8_t data[header.len - sizeof(header)];
     desc->chainRead(sizeof(header), data, sizeof(data));

     // Keep track of pending transactions
     parent.pendingTransactions[header.tag] = desc;

     DPRINTF(VIO9P, "recvTMsg\n");
     parent.dumpMsg(header, data, sizeof(data));

     // Notify device of message
     parent.recvTMsg(header, data, sizeof(data));
 }

 void
 VirtIO9PBase::sendRMsg(const P9MsgHeader &header, const uint8_t *data, size_t size)
 {
     DPRINTF(VIO9P, "Sending RMsg\n");
     dumpMsg(header, data, size);
     DPRINTF(VIO9P, "\tPending transactions: %i\n", pendingTransactions.size());
     assert(header.len >= sizeof(header));

     VirtDescriptor *main_desc(pendingTransactions[header.tag]);
     pendingTransactions.erase(header.tag);

     // Find the first output descriptor
     VirtDescriptor *out_desc(main_desc);
     while (out_desc && !out_desc->isOutgoing())
         out_desc = out_desc->next();
     if (!out_desc)
         panic("sendRMsg: Framing error, no output descriptor.\n");

     P9MsgHeader header_out(htop9(header));
     header_out.len = htop9(sizeof(P9MsgHeader) + size);

     out_desc->chainWrite(0, (uint8_t *)&header_out, sizeof(header_out));
     out_desc->chainWrite(sizeof(header_out), data, size);

     queue.produceDescriptor(main_desc, sizeof(P9MsgHeader) + size);
     kick();
 }

 void
 VirtIO9PBase::dumpMsg(const P9MsgHeader &header, const uint8_t *data, size_t size)
 {
 #ifndef NDEBUG
     if (!DTRACE(VIO9P))
         return;

     const P9MsgInfoMap::const_iterator it_msg(p9_msg_info.find(header.type));
     if (it_msg != p9_msg_info.cend()) {
         const P9MsgInfo &info(it_msg->second);
         DPRINTF(VIO9P, "P9Msg[len = %i, type = %s (%i), tag = %i]\n",
                 header.len, info.name, header.type, header.tag);
     } else {
         DPRINTF(VIO9P, "P9Msg[len = %i, type = Unknown (%i), tag = %i]\n",
                 header.len, header.type, header.tag);
     }
     DDUMP(VIO9PData, data, size);
 #endif
 }


 VirtIO9PProxy::VirtIO9PProxy(Params *params)
   : VirtIO9PBase(params), deviceUsed(false)
 {
 }

 VirtIO9PProxy::~VirtIO9PProxy()
 {
 }


 void
 VirtIO9PProxy::serialize(CheckpointOut &cp) const
 {
     if (deviceUsed) {
         warn("Serializing VirtIO9Base device after device has been used. It is "
              "likely that state will be lost, and that the device will cease "
              "to work!");
     }
     SERIALIZE_SCALAR(deviceUsed);

     VirtIO9PBase::serialize(cp);
 }

 void
 VirtIO9PProxy::unserialize(CheckpointIn &cp)
 {
     UNSERIALIZE_SCALAR(deviceUsed);

     if (deviceUsed) {
         warn("Unserializing VirtIO9Base device after device has been used. It is "
              "likely that state has been lost, and that the device will cease "
              "to work!");
     }
     VirtIO9PBase::unserialize(cp);
 }


 void
 VirtIO9PProxy::recvTMsg(const P9MsgHeader &header,
                         const uint8_t *data, size_t size)
 {
     deviceUsed = true;
     assert(header.len == sizeof(header) + size);
     // While technically not needed, we send the packet as one
     // contiguous segment to make some packet dissectors happy.
     uint8_t out[header.len];
     P9MsgHeader header_out(htop9(header));
     memcpy(out, (uint8_t *)&header_out, sizeof(header_out));
     memcpy(out + sizeof(header_out), data, size);
     writeAll(out, sizeof(header_out) + size);
 }

 void
 VirtIO9PProxy::serverDataReady()
 {
     P9MsgHeader header;
     readAll((uint8_t *)&header, sizeof(header));
     header = p9toh(header);

     const ssize_t payload_len(header.len - sizeof(header));
     if (payload_len < 0)
         panic("Payload length is negative!\n");
     uint8_t data[payload_len];
     readAll(data, payload_len);

     sendRMsg(header, data, payload_len);
 }


 void
 VirtIO9PProxy::readAll(uint8_t *data, size_t len)
 {
     while (len) {
         ssize_t ret;
         while ((ret = read(data, len)) == -EAGAIN)
             ;
         if (ret < 0)
             panic("readAll: Read failed: %i\n", -ret);

         len -= ret;
         data += ret;
     }
 }

 void
 VirtIO9PProxy::writeAll(const uint8_t *data, size_t len)
 {
     while (len) {
         ssize_t ret;
         while ((ret = write(data, len)) == -EAGAIN)
             ;
         if (ret < 0)
             panic("writeAll: write failed: %i\n", -ret);

         len -= ret;
         data += ret;
     }
 }


 VirtIO9PDiod::VirtIO9PDiod(Params *params)
     : VirtIO9PProxy(params),
       fd_to_diod(-1), fd_from_diod(-1), diod_pid(-1)
 {
     // Register an exit callback so we can kill the diod process
     Callback* cb = new MakeCallback<VirtIO9PDiod,
                                     &VirtIO9PDiod::terminateDiod>(this);
     registerExitCallback(cb);
 }

 VirtIO9PDiod::~VirtIO9PDiod()
 {
 }

 void
 VirtIO9PDiod::startup()
 {
     startDiod();
     dataEvent.reset(new DiodDataEvent(*this, fd_from_diod, POLLIN));
     pollQueue.schedule(dataEvent.get());
 }

 void
 VirtIO9PDiod::startDiod()
 {
     const Params *p(dynamic_cast<const Params *>(params()));
     int pipe_rfd[2];
     int pipe_wfd[2];
     const int DIOD_RFD = 3;
     const int DIOD_WFD = 4;

     const char *diod(p->diod.c_str());

     DPRINTF(VIO9P, "Using diod at %s \n", p->diod.c_str());

     if (pipe(pipe_rfd) == -1 || pipe(pipe_wfd) == -1)
         panic("Failed to create DIOD pipes: %i\n", errno);

     fd_to_diod = pipe_rfd[1];
     fd_from_diod = pipe_wfd[0];

     // Create Unix domain socket
     int socket_id = socket(AF_UNIX, SOCK_STREAM, 0);
     if (socket_id == -1) {
         panic("Socket creation failed %i \n", errno);
     }
     // Bind the socket to a path which will not be read
     struct sockaddr_un socket_address;
     memset(&socket_address, 0, sizeof(struct sockaddr_un));
     socket_address.sun_family = AF_UNIX;

     const std::string socket_path = simout.resolve(p->socketPath);
     fatal_if(!OutputDirectory::isAbsolute(socket_path), "Please make the" \
              " output directory an absolute path, else diod will fail!\n");

     // Prevent overflow in strcpy
     fatal_if(sizeof(socket_address.sun_path) <= socket_path.length(),
              "Incorrect length of socket path");
     strncpy(socket_address.sun_path, socket_path.c_str(),
             sizeof(socket_address.sun_path) - 1);
     if (bind(socket_id, (struct sockaddr*) &socket_address,
              sizeof(struct sockaddr_un)) == -1){
         perror("Socket binding");
         panic("Socket binding to %i failed - most likely the output dir" \
               " and hence unused socket already exists \n", socket_id);
     }

     diod_pid = fork();
     if (diod_pid == -1) {
         panic("Fork failed: %i\n", errno);
     } else if (diod_pid == 0) {
         // Create the socket which will later by used by the diod process
         close(STDIN_FILENO);
         if (dup2(pipe_rfd[0], DIOD_RFD) == -1 ||
             dup2(pipe_wfd[1], DIOD_WFD) == -1) {

             panic("Failed to setup read/write pipes: %i\n",
                   errno);
         }

         // Start diod
         execlp(diod, diod,
                "-f", // start in foreground
                "-r", "3", // setup read FD
                "-w", "4", // setup write FD
                "-e", p->root.c_str(), // path to export
                "-n", // disable security
                "-S", // squash all users
                "-l", socket_path.c_str(), // pass the socket
                (char *)NULL);
         perror("Starting DIOD");
         panic("Failed to execute diod to %s: %i\n",socket_path, errno);
     } else {
         close(pipe_rfd[0]);
         close(pipe_wfd[1]);
         inform("Started diod with PID %u, you might need to manually kill " \
                 " diod if gem5 crashes \n", diod_pid);
     }

 #undef DIOD_RFD
 #undef DIOD_WFD
 }

 ssize_t
 VirtIO9PDiod::read(uint8_t *data, size_t len)
 {
     assert(fd_from_diod != -1);
     const int ret(::read(fd_from_diod, (void *)data, len));
     return ret < 0 ? -errno : ret;
 }

 ssize_t
 VirtIO9PDiod::write(const uint8_t *data, size_t len)
 {
     assert(fd_to_diod != -1);
     const int ret(::write(fd_to_diod, (const void *)data, len));
     return ret < 0 ? -errno : ret;
 }

 void
 VirtIO9PDiod::DiodDataEvent::process(int revent)
 {
     parent.serverDataReady();
 }

 void
 VirtIO9PDiod::terminateDiod()
 {
     assert(diod_pid != -1);

     DPRINTF(VIO9P, "Trying to kill diod at pid %u \n", diod_pid);

     if (kill(diod_pid, SIGTERM) != 0) {
         perror("Killing diod process");
         warn("Failed to kill diod using SIGTERM");
         return;
     }

     // Check if kill worked
     for (unsigned i = 0; i < 5; i++) {
         int wait_return = waitpid(diod_pid, NULL, WNOHANG);
         if (wait_return == diod_pid) {
             // Managed to kill diod
             return;
         } else if (wait_return == 0) {
             // Diod is not killed so sleep and try again
             usleep(500);
         } else {
             // Failed in waitpid
             perror("Waitpid");
             warn("Failed in waitpid");
         }
     }

     // Try again to kill diod with sigkill
     inform("Trying to kill diod with SIGKILL as SIGTERM failed \n");
     if (kill(diod_pid, SIGKILL) != 0) {
         perror("Killing diod process");
         warn("Failed to kill diod using SIGKILL");
     } else {
         // Managed to kill diod
         return;
     }

 }
 VirtIO9PDiod *
 VirtIO9PDiodParams::create()
 {
     return new VirtIO9PDiod(this);
 }


 VirtIO9PSocket::VirtIO9PSocket(Params *params)
     : VirtIO9PProxy(params), fdSocket(-1)
 {
 }

 VirtIO9PSocket::~VirtIO9PSocket()
 {
 }

 void
 VirtIO9PSocket::startup()
 {
     connectSocket();
     dataEvent.reset(new SocketDataEvent(*this, fdSocket, POLLIN));
     pollQueue.schedule(dataEvent.get());
 }

 void
 VirtIO9PSocket::connectSocket()
 {
     const Params &p(dynamic_cast<const Params &>(*params()));

     int ret;
     struct addrinfo hints, *result;
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = AF_UNSPEC;
     hints.ai_socktype = SOCK_STREAM;
     hints.ai_flags = 0;
     hints.ai_protocol = 0;

     if ((ret = getaddrinfo(p.server.c_str(), p.port.c_str(),
                            &hints, &result)) != 0)
         panic("getaddrinfo: %s\n", gai_strerror(ret));

     DPRINTF(VIO9P, "Connecting to 9p server '%s'.\n", p.server);
     for (struct addrinfo *rp = result; rp; rp = rp->ai_next) {
         fdSocket = socket(rp->ai_family, rp->ai_socktype,
                      rp->ai_protocol);
         if (fdSocket == -1) {
             continue;
         } else if (connect(fdSocket, rp->ai_addr, rp->ai_addrlen) != -1) {
             break;
         } else {
             close(fdSocket);
             fdSocket = -1;
         }
     }

     freeaddrinfo(result);

     if (fdSocket == -1)
         panic("Failed to connect to 9p server (%s:%s)", p.server, p.port);
 }

 void
 VirtIO9PSocket::socketDisconnect()
 {
     panic("9P Socket disconnected!\n");
 }

 ssize_t
 VirtIO9PSocket::read(uint8_t *data, size_t len)
 {
     assert(fdSocket != -1);
     int ret;

     ret = ::recv(fdSocket, (void *)data, len, 0);
     if (ret == 0)
         socketDisconnect();

     return ret < 0 ? -errno : ret;
 }

 ssize_t
 VirtIO9PSocket::write(const uint8_t *data, size_t len)
 {
     assert(fdSocket != -1);
     int ret(::send(fdSocket, (const void *)data, len, 0));
     return ret < 0 ? -errno : ret;
 }

 void
 VirtIO9PSocket::SocketDataEvent::process(int revent)
 {
     parent.serverDataReady();
 }


 VirtIO9PSocket *
 VirtIO9PSocketParams::create()
 {
     return new VirtIO9PSocket(this);
 }
	/*
	* Copyright (c) 2014-2017 ARM Limited
	* All rights reserved
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* property including but not limited to intellectual property relating
	* to a hardware implementation of the functionality of the software
	* licensed hereunder. You may use the software subject to the license
	* terms below provided that you ensure that this notice is replicated
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* Authors: Andreas Sandberg
	*/

	#include "dev/virtio/fs9p.hh"

	#include <fcntl.h>
	#include <netdb.h>
	#include <netinet/in.h>
	#include <sys/socket.h>
	#include <sys/types.h>
	#include <sys/un.h>
	#include <sys/wait.h>
	#include <unistd.h>

	#include <csignal>
	#include <fstream>

	#include "base/callback.hh"
	#include "base/output.hh"
	#include "debug/VIO9P.hh"
	#include "debug/VIO9PData.hh"
	#include "params/VirtIO9PBase.hh"
	#include "params/VirtIO9PDiod.hh"
	#include "params/VirtIO9PProxy.hh"
	#include "params/VirtIO9PSocket.hh"
	#include "sim/system.hh"

	struct P9MsgInfo {
	P9MsgInfo(P9MsgType _type, std::string _name)
	: type(_type), name(_name) {}

	P9MsgType type;
	std::string name;
	};

	typedef std::map<P9MsgType, P9MsgInfo> P9MsgInfoMap;

	#define P9MSG(type, name) \
	{ (type), P9MsgInfo((type), "T" # name ) }, \
	{ (type + 1), P9MsgInfo((type + 1), "R" # name ) }

	static const P9MsgInfoMap p9_msg_info {
	P9MSG(6, LERROR),
	P9MSG(8, STATFS),
	P9MSG(12, LOPEN),
	P9MSG(14, LCREATE),
	P9MSG(16, SYMLINK),
	P9MSG(18, MKNOD),
	P9MSG(20, RENAME),
	P9MSG(22, READLINK),
	P9MSG(24, GETATTR),
	P9MSG(26, SETATTR),
	P9MSG(30, XATTRWALK),
	P9MSG(32, XATTRCREATE),
	P9MSG(40, READDIR),
	P9MSG(50, FSYNC),
	P9MSG(52, LOCK),
	P9MSG(54, GETLOCK),
	P9MSG(70, LINK),
	P9MSG(72, MKDIR),
	P9MSG(74, RENAMEAT),
	P9MSG(76, UNLINKAT),
	P9MSG(100, VERSION),
	P9MSG(102, AUTH),
	P9MSG(104, ATTACH),
	P9MSG(106, ERROR),
	P9MSG(108, FLUSH),
	P9MSG(110, WALK),
	P9MSG(112, OPEN),
	P9MSG(114, CREATE),
	P9MSG(116, READ),
	P9MSG(118, WRITE),
	P9MSG(120, CLUNK),
	P9MSG(122, REMOVE),
	P9MSG(124, STAT),
	P9MSG(126, WSTAT),
	};

	#undef P9MSG

	VirtIO9PBase::VirtIO9PBase(Params *params)
	: VirtIODeviceBase(params, ID_9P,
	sizeof(Config) + params->tag.size(),
	F_MOUNT_TAG),
	queue(params->system->physProxy, params->queueSize, *this)
	{
	config.reset((Config *)
	operator new(configSize));
	config->len = htov_legacy(params->tag.size());
	memcpy(config->tag, params->tag.c_str(), params->tag.size());

	registerQueue(queue);
	}


	VirtIO9PBase::~VirtIO9PBase()
	{
	}

	void
	VirtIO9PBase::readConfig(PacketPtr pkt, Addr cfgOffset)
	{
	readConfigBlob(pkt, cfgOffset, (uint8_t *)config.get());
	}

	void
	VirtIO9PBase::FSQueue::onNotifyDescriptor(VirtDescriptor *desc)
	{
	DPRINTF(VIO9P, "Got input data descriptor (len: %i)\n", desc->size());
	DPRINTF(VIO9P, "\tPending transactions: %i\n", parent.pendingTransactions.size());

	P9MsgHeader header;
	desc->chainRead(0, (uint8_t *)&header, sizeof(header));
	header = p9toh(header);

	uint8_t data[header.len - sizeof(header)];
	desc->chainRead(sizeof(header), data, sizeof(data));

	// Keep track of pending transactions
	parent.pendingTransactions[header.tag] = desc;

	DPRINTF(VIO9P, "recvTMsg\n");
	parent.dumpMsg(header, data, sizeof(data));

	// Notify device of message
	parent.recvTMsg(header, data, sizeof(data));
	}

	void
	VirtIO9PBase::sendRMsg(const P9MsgHeader &header, const uint8_t *data, size_t size)
	{
	DPRINTF(VIO9P, "Sending RMsg\n");
	dumpMsg(header, data, size);
	DPRINTF(VIO9P, "\tPending transactions: %i\n", pendingTransactions.size());
	assert(header.len >= sizeof(header));

	VirtDescriptor *main_desc(pendingTransactions[header.tag]);
	pendingTransactions.erase(header.tag);

	// Find the first output descriptor
	VirtDescriptor *out_desc(main_desc);
	while (out_desc && !out_desc->isOutgoing())
	out_desc = out_desc->next();
	if (!out_desc)
	panic("sendRMsg: Framing error, no output descriptor.\n");

	P9MsgHeader header_out(htop9(header));
	header_out.len = htop9(sizeof(P9MsgHeader) + size);

	out_desc->chainWrite(0, (uint8_t *)&header_out, sizeof(header_out));
	out_desc->chainWrite(sizeof(header_out), data, size);

	queue.produceDescriptor(main_desc, sizeof(P9MsgHeader) + size);
	kick();
	}

	void
	VirtIO9PBase::dumpMsg(const P9MsgHeader &header, const uint8_t *data, size_t size)
	{
	#ifndef NDEBUG
	if (!DTRACE(VIO9P))
	return;

	const P9MsgInfoMap::const_iterator it_msg(p9_msg_info.find(header.type));
	if (it_msg != p9_msg_info.cend()) {
	const P9MsgInfo &info(it_msg->second);
	DPRINTF(VIO9P, "P9Msg[len = %i, type = %s (%i), tag = %i]\n",
	header.len, info.name, header.type, header.tag);
	} else {
	DPRINTF(VIO9P, "P9Msg[len = %i, type = Unknown (%i), tag = %i]\n",
	header.len, header.type, header.tag);
	}
	DDUMP(VIO9PData, data, size);
	#endif
	}


	VirtIO9PProxy::VirtIO9PProxy(Params *params)
	: VirtIO9PBase(params), deviceUsed(false)
	{
	}

	VirtIO9PProxy::~VirtIO9PProxy()
	{
	}


	void
	VirtIO9PProxy::serialize(CheckpointOut &cp) const
	{
	if (deviceUsed) {
	warn("Serializing VirtIO9Base device after device has been used. It is "
	"likely that state will be lost, and that the device will cease "
	"to work!");
	}
	SERIALIZE_SCALAR(deviceUsed);

	VirtIO9PBase::serialize(cp);
	}

	void
	VirtIO9PProxy::unserialize(CheckpointIn &cp)
	{
	UNSERIALIZE_SCALAR(deviceUsed);

	if (deviceUsed) {
	warn("Unserializing VirtIO9Base device after device has been used. It is "
	"likely that state has been lost, and that the device will cease "
	"to work!");
	}
	VirtIO9PBase::unserialize(cp);
	}


	void
	VirtIO9PProxy::recvTMsg(const P9MsgHeader &header,
	const uint8_t *data, size_t size)
	{
	deviceUsed = true;
	assert(header.len == sizeof(header) + size);
	// While technically not needed, we send the packet as one
	// contiguous segment to make some packet dissectors happy.
	uint8_t out[header.len];
	P9MsgHeader header_out(htop9(header));
	memcpy(out, (uint8_t *)&header_out, sizeof(header_out));
	memcpy(out + sizeof(header_out), data, size);
	writeAll(out, sizeof(header_out) + size);
	}

	void
	VirtIO9PProxy::serverDataReady()
	{
	P9MsgHeader header;
	readAll((uint8_t *)&header, sizeof(header));
	header = p9toh(header);

	const ssize_t payload_len(header.len - sizeof(header));
	if (payload_len < 0)
	panic("Payload length is negative!\n");
	uint8_t data[payload_len];
	readAll(data, payload_len);

	sendRMsg(header, data, payload_len);
	}


	void
	VirtIO9PProxy::readAll(uint8_t *data, size_t len)
	{
	while (len) {
	ssize_t ret;
	while ((ret = read(data, len)) == -EAGAIN)
	;
	if (ret < 0)
	panic("readAll: Read failed: %i\n", -ret);

	len -= ret;
	data += ret;
	}
	}

	void
	VirtIO9PProxy::writeAll(const uint8_t *data, size_t len)
	{
	while (len) {
	ssize_t ret;
	while ((ret = write(data, len)) == -EAGAIN)
	;
	if (ret < 0)
	panic("writeAll: write failed: %i\n", -ret);

	len -= ret;
	data += ret;
	}
	}



	VirtIO9PDiod::VirtIO9PDiod(Params *params)
	: VirtIO9PProxy(params),
	fd_to_diod(-1), fd_from_diod(-1), diod_pid(-1)
	{
	// Register an exit callback so we can kill the diod process
	Callback* cb = new MakeCallback<VirtIO9PDiod,
	&VirtIO9PDiod::terminateDiod>(this);
	registerExitCallback(cb);
	}

	VirtIO9PDiod::~VirtIO9PDiod()
	{
	}

	void
	VirtIO9PDiod::startup()
	{
	startDiod();
	dataEvent.reset(new DiodDataEvent(*this, fd_from_diod, POLLIN));
	pollQueue.schedule(dataEvent.get());
	}

	void
	VirtIO9PDiod::startDiod()
	{
	const Params p(dynamic_cast<const Params >(params()));
	int pipe_rfd[2];
	int pipe_wfd[2];
	const int DIOD_RFD = 3;
	const int DIOD_WFD = 4;

	const char *diod(p->diod.c_str());

	DPRINTF(VIO9P, "Using diod at %s \n", p->diod.c_str());

	if (pipe(pipe_rfd) == -1 \|\| pipe(pipe_wfd) == -1)
	panic("Failed to create DIOD pipes: %i\n", errno);

	fd_to_diod = pipe_rfd[1];
	fd_from_diod = pipe_wfd[0];

	// Create Unix domain socket
	int socket_id = socket(AF_UNIX, SOCK_STREAM, 0);
	if (socket_id == -1) {
	panic("Socket creation failed %i \n", errno);
	}
	// Bind the socket to a path which will not be read
	struct sockaddr_un socket_address;
	memset(&socket_address, 0, sizeof(struct sockaddr_un));
	socket_address.sun_family = AF_UNIX;

	const std::string socket_path = simout.resolve(p->socketPath);
	fatal_if(!OutputDirectory::isAbsolute(socket_path), "Please make the" \
	" output directory an absolute path, else diod will fail!\n");

	// Prevent overflow in strcpy
	fatal_if(sizeof(socket_address.sun_path) <= socket_path.length(),
	"Incorrect length of socket path");
	strncpy(socket_address.sun_path, socket_path.c_str(),
	sizeof(socket_address.sun_path) - 1);
	if (bind(socket_id, (struct sockaddr*) &socket_address,
	sizeof(struct sockaddr_un)) == -1){
	perror("Socket binding");
	panic("Socket binding to %i failed - most likely the output dir" \
	" and hence unused socket already exists \n", socket_id);
	}

	diod_pid = fork();
	if (diod_pid == -1) {
	panic("Fork failed: %i\n", errno);
	} else if (diod_pid == 0) {
	// Create the socket which will later by used by the diod process
	close(STDIN_FILENO);
	if (dup2(pipe_rfd[0], DIOD_RFD) == -1 \|\|
	dup2(pipe_wfd[1], DIOD_WFD) == -1) {

	panic("Failed to setup read/write pipes: %i\n",
	errno);
	}

	// Start diod
	execlp(diod, diod,
	"-f", // start in foreground
	"-r", "3", // setup read FD
	"-w", "4", // setup write FD
	"-e", p->root.c_str(), // path to export
	"-n", // disable security
	"-S", // squash all users
	"-l", socket_path.c_str(), // pass the socket
	(char *)NULL);
	perror("Starting DIOD");
	panic("Failed to execute diod to %s: %i\n",socket_path, errno);
	} else {
	close(pipe_rfd[0]);
	close(pipe_wfd[1]);
	inform("Started diod with PID %u, you might need to manually kill " \
	" diod if gem5 crashes \n", diod_pid);
	}

	#undef DIOD_RFD
	#undef DIOD_WFD
	}

	ssize_t
	VirtIO9PDiod::read(uint8_t *data, size_t len)
	{
	assert(fd_from_diod != -1);
	const int ret(::read(fd_from_diod, (void *)data, len));
	return ret < 0 ? -errno : ret;
	}

	ssize_t
	VirtIO9PDiod::write(const uint8_t *data, size_t len)
	{
	assert(fd_to_diod != -1);
	const int ret(::write(fd_to_diod, (const void *)data, len));
	return ret < 0 ? -errno : ret;
	}

	void
	VirtIO9PDiod::DiodDataEvent::process(int revent)
	{
	parent.serverDataReady();
	}

	void
	VirtIO9PDiod::terminateDiod()
	{
	assert(diod_pid != -1);

	DPRINTF(VIO9P, "Trying to kill diod at pid %u \n", diod_pid);

	if (kill(diod_pid, SIGTERM) != 0) {
	perror("Killing diod process");
	warn("Failed to kill diod using SIGTERM");
	return;
	}

	// Check if kill worked
	for (unsigned i = 0; i < 5; i++) {
	int wait_return = waitpid(diod_pid, NULL, WNOHANG);
	if (wait_return == diod_pid) {
	// Managed to kill diod
	return;
	} else if (wait_return == 0) {
	// Diod is not killed so sleep and try again
	usleep(500);
	} else {
	// Failed in waitpid
	perror("Waitpid");
	warn("Failed in waitpid");
	}
	}

	// Try again to kill diod with sigkill
	inform("Trying to kill diod with SIGKILL as SIGTERM failed \n");
	if (kill(diod_pid, SIGKILL) != 0) {
	perror("Killing diod process");
	warn("Failed to kill diod using SIGKILL");
	} else {
	// Managed to kill diod
	return;
	}

	}
	VirtIO9PDiod *
	VirtIO9PDiodParams::create()
	{
	return new VirtIO9PDiod(this);
	}




	VirtIO9PSocket::VirtIO9PSocket(Params *params)
	: VirtIO9PProxy(params), fdSocket(-1)
	{
	}

	VirtIO9PSocket::~VirtIO9PSocket()
	{
	}

	void
	VirtIO9PSocket::startup()
	{
	connectSocket();
	dataEvent.reset(new SocketDataEvent(*this, fdSocket, POLLIN));
	pollQueue.schedule(dataEvent.get());
	}

	void
	VirtIO9PSocket::connectSocket()
	{
	const Params &p(dynamic_cast<const Params &>(*params()));

	int ret;
	struct addrinfo hints, *result;
	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = 0;
	hints.ai_protocol = 0;

	if ((ret = getaddrinfo(p.server.c_str(), p.port.c_str(),
	&hints, &result)) != 0)
	panic("getaddrinfo: %s\n", gai_strerror(ret));

	DPRINTF(VIO9P, "Connecting to 9p server '%s'.\n", p.server);
	for (struct addrinfo *rp = result; rp; rp = rp->ai_next) {
	fdSocket = socket(rp->ai_family, rp->ai_socktype,
	rp->ai_protocol);
	if (fdSocket == -1) {
	continue;
	} else if (connect(fdSocket, rp->ai_addr, rp->ai_addrlen) != -1) {
	break;
	} else {
	close(fdSocket);
	fdSocket = -1;
	}
	}

	freeaddrinfo(result);

	if (fdSocket == -1)
	panic("Failed to connect to 9p server (%s:%s)", p.server, p.port);
	}

	void
	VirtIO9PSocket::socketDisconnect()
	{
	panic("9P Socket disconnected!\n");
	}

	ssize_t
	VirtIO9PSocket::read(uint8_t *data, size_t len)
	{
	assert(fdSocket != -1);
	int ret;

	ret = ::recv(fdSocket, (void *)data, len, 0);
	if (ret == 0)
	socketDisconnect();

	return ret < 0 ? -errno : ret;
	}

	ssize_t
	VirtIO9PSocket::write(const uint8_t *data, size_t len)
	{
	assert(fdSocket != -1);
	int ret(::send(fdSocket, (const void *)data, len, 0));
	return ret < 0 ? -errno : ret;
	}

	void
	VirtIO9PSocket::SocketDataEvent::process(int revent)
	{
	parent.serverDataReady();
	}


	VirtIO9PSocket *
	VirtIO9PSocketParams::create()
	{
	return new VirtIO9PSocket(this);
	}