--- /dev/null
+/*
+ * An implementation of file copy service.
+ *
+ * Copyright (C) 2014, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for more
+ * details.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/semaphore.h>
+#include <linux/fs.h>
+#include <linux/nls.h>
+#include <linux/workqueue.h>
+#include <linux/cdev.h>
+#include <linux/hyperv.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+
+#include "hyperv_vmbus.h"
+
+#define WIN8_SRV_MAJOR 1
+#define WIN8_SRV_MINOR 1
+#define WIN8_SRV_VERSION (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
+
+/*
+ * Global state maintained for transaction that is being processed.
+ * For a class of integration services, including the "file copy service",
+ * the specified protocol is a "request/response" protocol which means that
+ * there can only be single outstanding transaction from the host at any
+ * given point in time. We use this to simplify memory management in this
+ * driver - we cache and process only one message at a time.
+ *
+ * While the request/response protocol is guaranteed by the host, we further
+ * ensure this by serializing packet processing in this driver - we do not
+ * read additional packets from the VMBUs until the current packet is fully
+ * handled.
+ *
+ * The transaction "active" state is set when we receive a request from the
+ * host and we cleanup this state when the transaction is completed - when we
+ * respond to the host with our response. When the transaction active state is
+ * set, we defer handling incoming packets.
+ */
+
+static struct {
+ bool active; /* transaction status - active or not */
+ int recv_len; /* number of bytes received. */
+ struct hv_fcopy_hdr *fcopy_msg; /* current message */
+ struct hv_start_fcopy message; /* sent to daemon */
+ struct vmbus_channel *recv_channel; /* chn we got the request */
+ u64 recv_req_id; /* request ID. */
+ void *fcopy_context; /* for the channel callback */
+ struct semaphore read_sema;
+} fcopy_transaction;
+
+static bool opened; /* currently device opened */
+
+/*
+ * Before we can accept copy messages from the host, we need
+ * to handshake with the user level daemon. This state tracks
+ * if we are in the handshake phase.
+ */
+static bool in_hand_shake = true;
+static void fcopy_send_data(void);
+static void fcopy_respond_to_host(int error);
+static void fcopy_work_func(struct work_struct *dummy);
+static DECLARE_DELAYED_WORK(fcopy_work, fcopy_work_func);
+static u8 *recv_buffer;
+
+static void fcopy_work_func(struct work_struct *dummy)
+{
+ /*
+ * If the timer fires, the user-mode component has not responded;
+ * process the pending transaction.
+ */
+ fcopy_respond_to_host(HV_E_FAIL);
+
+ /* In the case the user-space daemon crashes, hangs or is killed, we
+ * need to down the semaphore, otherwise, after the daemon starts next
+ * time, the obsolete data in fcopy_transaction.message or
+ * fcopy_transaction.fcopy_msg will be used immediately.
+ *
+ * NOTE: fcopy_read() happens to get the semaphore (very rare)? We're
+ * still OK, because we've reported the failure to the host.
+ */
+ if (down_trylock(&fcopy_transaction.read_sema))
+ ;
+
+}
+
+static int fcopy_handle_handshake(u32 version)
+{
+ switch (version) {
+ case FCOPY_CURRENT_VERSION:
+ break;
+ default:
+ /*
+ * For now we will fail the registration.
+ * If and when we have multiple versions to
+ * deal with, we will be backward compatible.
+ * We will add this code when needed.
+ */
+ return -EINVAL;
+ }
+ pr_info("FCP: user-mode registering done. Daemon version: %d\n",
+ version);
+ fcopy_transaction.active = false;
+ if (fcopy_transaction.fcopy_context)
+ hv_fcopy_onchannelcallback(fcopy_transaction.fcopy_context);
+ in_hand_shake = false;
+ return 0;
+}
+
+static void fcopy_send_data(void)
+{
+ struct hv_start_fcopy *smsg_out = &fcopy_transaction.message;
+ int operation = fcopy_transaction.fcopy_msg->operation;
+ struct hv_start_fcopy *smsg_in;
+
+ /*
+ * The strings sent from the host are encoded in
+ * in utf16; convert it to utf8 strings.
+ * The host assures us that the utf16 strings will not exceed
+ * the max lengths specified. We will however, reserve room
+ * for the string terminating character - in the utf16s_utf8s()
+ * function we limit the size of the buffer where the converted
+ * string is placed to W_MAX_PATH -1 to guarantee
+ * that the strings can be properly terminated!
+ */
+
+ switch (operation) {
+ case START_FILE_COPY:
+ memset(smsg_out, 0, sizeof(struct hv_start_fcopy));
+ smsg_out->hdr.operation = operation;
+ smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
+
+ utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
+ UTF16_LITTLE_ENDIAN,
+ (__u8 *)smsg_out->file_name, W_MAX_PATH - 1);
+
+ utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
+ UTF16_LITTLE_ENDIAN,
+ (__u8 *)smsg_out->path_name, W_MAX_PATH - 1);
+
+ smsg_out->copy_flags = smsg_in->copy_flags;
+ smsg_out->file_size = smsg_in->file_size;
+ break;
+
+ default:
+ break;
+ }
+ up(&fcopy_transaction.read_sema);
+ return;
+}
+
+/*
+ * Send a response back to the host.
+ */
+
+static void
+fcopy_respond_to_host(int error)
+{
+ struct icmsg_hdr *icmsghdr;
+ u32 buf_len;
+ struct vmbus_channel *channel;
+ u64 req_id;
+
+ /*
+ * Copy the global state for completing the transaction. Note that
+ * only one transaction can be active at a time. This is guaranteed
+ * by the file copy protocol implemented by the host. Furthermore,
+ * the "transaction active" state we maintain ensures that there can
+ * only be one active transaction at a time.
+ */
+
+ buf_len = fcopy_transaction.recv_len;
+ channel = fcopy_transaction.recv_channel;
+ req_id = fcopy_transaction.recv_req_id;
+
+ fcopy_transaction.active = false;
+
+ icmsghdr = (struct icmsg_hdr *)
+ &recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+ if (channel->onchannel_callback == NULL)
+ /*
+ * We have raced with util driver being unloaded;
+ * silently return.
+ */
+ return;
+
+ icmsghdr->status = error;
+ icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+ vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
+ VM_PKT_DATA_INBAND, 0);
+}
+
+void hv_fcopy_onchannelcallback(void *context)
+{
+ struct vmbus_channel *channel = context;
+ u32 recvlen;
+ u64 requestid;
+ struct hv_fcopy_hdr *fcopy_msg;
+ struct icmsg_hdr *icmsghdr;
+ struct icmsg_negotiate *negop = NULL;
+ int util_fw_version;
+ int fcopy_srv_version;
+
+ if (fcopy_transaction.active) {
+ /*
+ * We will defer processing this callback once
+ * the current transaction is complete.
+ */
+ fcopy_transaction.fcopy_context = context;
+ return;
+ }
+
+ vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
+ &requestid);
+ if (recvlen <= 0)
+ return;
+
+ icmsghdr = (struct icmsg_hdr *)&recv_buffer[
+ sizeof(struct vmbuspipe_hdr)];
+ if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+ util_fw_version = UTIL_FW_VERSION;
+ fcopy_srv_version = WIN8_SRV_VERSION;
+ vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
+ util_fw_version, fcopy_srv_version);
+ } else {
+ fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
+ sizeof(struct vmbuspipe_hdr) +
+ sizeof(struct icmsg_hdr)];
+
+ /*
+ * Stash away this global state for completing the
+ * transaction; note transactions are serialized.
+ */
+
+ fcopy_transaction.active = true;
+ fcopy_transaction.recv_len = recvlen;
+ fcopy_transaction.recv_channel = channel;
+ fcopy_transaction.recv_req_id = requestid;
+ fcopy_transaction.fcopy_msg = fcopy_msg;
+
+ /*
+ * Send the information to the user-level daemon.
+ */
+ schedule_delayed_work(&fcopy_work, 5*HZ);
+ fcopy_send_data();
+ return;
+ }
+ icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+ vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
+ VM_PKT_DATA_INBAND, 0);
+}
+
+/*
+ * Create a char device that can support read/write for passing
+ * the payload.
+ */
+
+static ssize_t fcopy_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ void *src;
+ size_t copy_size;
+ int operation;
+
+ /*
+ * Wait until there is something to be read.
+ */
+ if (down_interruptible(&fcopy_transaction.read_sema))
+ return -EINTR;
+
+ /*
+ * The channel may be rescinded and in this case, we will wakeup the
+ * the thread blocked on the semaphore and we will use the opened
+ * state to correctly handle this case.
+ */
+ if (!opened)
+ return -ENODEV;
+
+ operation = fcopy_transaction.fcopy_msg->operation;
+
+ if (operation == START_FILE_COPY) {
+ src = &fcopy_transaction.message;
+ copy_size = sizeof(struct hv_start_fcopy);
+ if (count < copy_size)
+ return 0;
+ } else {
+ src = fcopy_transaction.fcopy_msg;
+ copy_size = sizeof(struct hv_do_fcopy);
+ if (count < copy_size)
+ return 0;
+ }
+ if (copy_to_user(buf, src, copy_size))
+ return -EFAULT;
+
+ return copy_size;
+}
+
+static ssize_t fcopy_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ int response = 0;
+
+ if (count != sizeof(int))
+ return -EINVAL;
+
+ if (copy_from_user(&response, buf, sizeof(int)))
+ return -EFAULT;
+
+ if (in_hand_shake) {
+ if (fcopy_handle_handshake(response))
+ return -EINVAL;
+ return sizeof(int);
+ }
+
+ /*
+ * Complete the transaction by forwarding the result
+ * to the host. But first, cancel the timeout.
+ */
+ if (cancel_delayed_work_sync(&fcopy_work))
+ fcopy_respond_to_host(response);
+
+ return sizeof(int);
+}
+
+static int fcopy_open(struct inode *inode, struct file *f)
+{
+ /*
+ * The user level daemon that will open this device is
+ * really an extension of this driver. We can have only
+ * active open at a time.
+ */
+ if (opened)
+ return -EBUSY;
+
+ /*
+ * The daemon is alive; setup the state.
+ */
+ opened = true;
+ return 0;
+}
+
+/* XXX: there are still some tricky corner cases, e.g.,
+ * 1) In a SMP guest, when fcopy_release() runs between
+ * schedule_delayed_work() and fcopy_send_data(), there is
+ * still a chance an obsolete message will be queued.
+ *
+ * 2) When the fcopy daemon is running, if we unload the driver,
+ * we'll notice a kernel oops when we kill the daemon later.
+ */
+static int fcopy_release(struct inode *inode, struct file *f)
+{
+ /*
+ * The daemon has exited; reset the state.
+ */
+ in_hand_shake = true;
+ opened = false;
+
+ if (cancel_delayed_work_sync(&fcopy_work)) {
+ /* We haven't up()-ed the semaphore(very rare)? */
+ if (down_trylock(&fcopy_transaction.read_sema))
+ ;
+ fcopy_respond_to_host(HV_E_FAIL);
+ }
+ return 0;
+}
+
+
+static const struct file_operations fcopy_fops = {
+ .read = fcopy_read,
+ .write = fcopy_write,
+ .release = fcopy_release,
+ .open = fcopy_open,
+};
+
+static struct miscdevice fcopy_misc = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "vmbus/hv_fcopy",
+ .fops = &fcopy_fops,
+};
+
+static int fcopy_dev_init(void)
+{
+ return misc_register(&fcopy_misc);
+}
+
+static void fcopy_dev_deinit(void)
+{
+
+ /*
+ * The device is going away - perhaps because the
+ * host has rescinded the channel. Setup state so that
+ * user level daemon can gracefully exit if it is blocked
+ * on the read semaphore.
+ */
+ opened = false;
+ /*
+ * Signal the semaphore as the device is
+ * going away.
+ */
+ up(&fcopy_transaction.read_sema);
+ misc_deregister(&fcopy_misc);
+}
+
+int hv_fcopy_init(struct hv_util_service *srv)
+{
+ recv_buffer = srv->recv_buffer;
+
+ /*
+ * When this driver loads, the user level daemon that
+ * processes the host requests may not yet be running.
+ * Defer processing channel callbacks until the daemon
+ * has registered.
+ */
+ fcopy_transaction.active = true;
+ sema_init(&fcopy_transaction.read_sema, 0);
+
+ return fcopy_dev_init();
+}
+
+void hv_fcopy_deinit(void)
+{
+ cancel_delayed_work_sync(&fcopy_work);
+ fcopy_dev_deinit();
+}
Code Review / kvmfornfv.git / blobdiff