linux/drivers/hv/hv_fcopy.c
Dexuan Cui 54e19d3401 hv_utils: Add the support of hibernation
Add util_pre_suspend() and util_pre_resume() for some hv_utils devices
(e.g. kvp/vss/fcopy), because they need special handling before
util_suspend() calls vmbus_close().

For kvp, all the possible pending work items should be cancelled.

For vss and fcopy, some extra clean-up needs to be done, i.e. fake a
THAW message for hv_vss_daemon and fake a CANCEL_FCOPY message for
hv_fcopy_daemon, otherwise when the VM resums back, the daemons
can end up in an inconsistent state (i.e. the file systems are
frozen but will never be thawed; the file transmitted via fcopy
may not be complete). Note: there is an extra patch for the daemons:
"Tools: hv: Reopen the devices if read() or write() returns errors",
because the hv_utils driver can not guarantee the whole transaction
finishes completely once util_suspend() starts to run (at this time,
all the userspace processes are frozen).

util_probe() disables channel->callback_event to avoid the race with
the channel callback.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-01-26 22:10:17 -05:00

407 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* An implementation of file copy service.
*
* Copyright (C) 2014, Microsoft, Inc.
*
* Author : K. Y. Srinivasan <ksrinivasan@novell.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/nls.h>
#include <linux/workqueue.h>
#include <linux/hyperv.h>
#include <linux/sched.h>
#include <asm/hyperv-tlfs.h>
#include "hyperv_vmbus.h"
#include "hv_utils_transport.h"
#define WIN8_SRV_MAJOR 1
#define WIN8_SRV_MINOR 1
#define WIN8_SRV_VERSION (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
#define FCOPY_VER_COUNT 1
static const int fcopy_versions[] = {
WIN8_SRV_VERSION
};
#define FW_VER_COUNT 1
static const int fw_versions[] = {
UTIL_FW_VERSION
};
/*
* 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.
*/
static struct {
int state; /* hvutil_device_state */
int recv_len; /* number of bytes received. */
struct hv_fcopy_hdr *fcopy_msg; /* current message */
struct vmbus_channel *recv_channel; /* chn we got the request */
u64 recv_req_id; /* request ID. */
} fcopy_transaction;
static void fcopy_respond_to_host(int error);
static void fcopy_send_data(struct work_struct *dummy);
static void fcopy_timeout_func(struct work_struct *dummy);
static DECLARE_DELAYED_WORK(fcopy_timeout_work, fcopy_timeout_func);
static DECLARE_WORK(fcopy_send_work, fcopy_send_data);
static const char fcopy_devname[] = "vmbus/hv_fcopy";
static u8 *recv_buffer;
static struct hvutil_transport *hvt;
/*
* This state maintains the version number registered by the daemon.
*/
static int dm_reg_value;
static void fcopy_poll_wrapper(void *channel)
{
/* Transaction is finished, reset the state here to avoid races. */
fcopy_transaction.state = HVUTIL_READY;
hv_fcopy_onchannelcallback(channel);
}
static void fcopy_timeout_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);
hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
}
static void fcopy_register_done(void)
{
pr_debug("FCP: userspace daemon registered\n");
hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
}
static int fcopy_handle_handshake(u32 version)
{
u32 our_ver = FCOPY_CURRENT_VERSION;
switch (version) {
case FCOPY_VERSION_0:
/* Daemon doesn't expect us to reply */
dm_reg_value = version;
break;
case FCOPY_VERSION_1:
/* Daemon expects us to reply with our own version */
if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
fcopy_register_done))
return -EFAULT;
dm_reg_value = 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_debug("FCP: userspace daemon ver. %d connected\n", version);
return 0;
}
static void fcopy_send_data(struct work_struct *dummy)
{
struct hv_start_fcopy *smsg_out = NULL;
int operation = fcopy_transaction.fcopy_msg->operation;
struct hv_start_fcopy *smsg_in;
void *out_src;
int rc, out_len;
/*
* 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:
out_len = sizeof(struct hv_start_fcopy);
smsg_out = kzalloc(sizeof(*smsg_out), GFP_KERNEL);
if (!smsg_out)
return;
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;
out_src = smsg_out;
break;
case WRITE_TO_FILE:
out_src = fcopy_transaction.fcopy_msg;
out_len = sizeof(struct hv_do_fcopy);
break;
default:
out_src = fcopy_transaction.fcopy_msg;
out_len = fcopy_transaction.recv_len;
break;
}
fcopy_transaction.state = HVUTIL_USERSPACE_REQ;
rc = hvutil_transport_send(hvt, out_src, out_len, NULL);
if (rc) {
pr_debug("FCP: failed to communicate to the daemon: %d\n", rc);
if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
fcopy_respond_to_host(HV_E_FAIL);
fcopy_transaction.state = HVUTIL_READY;
}
}
kfree(smsg_out);
}
/*
* 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;
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;
int fcopy_srv_version;
if (fcopy_transaction.state > HVUTIL_READY)
return;
vmbus_recvpacket(channel, recv_buffer, HV_HYP_PAGE_SIZE * 2, &recvlen,
&requestid);
if (recvlen <= 0)
return;
icmsghdr = (struct icmsg_hdr *)&recv_buffer[
sizeof(struct vmbuspipe_hdr)];
if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
if (vmbus_prep_negotiate_resp(icmsghdr, recv_buffer,
fw_versions, FW_VER_COUNT,
fcopy_versions, FCOPY_VER_COUNT,
NULL, &fcopy_srv_version)) {
pr_info("FCopy IC version %d.%d\n",
fcopy_srv_version >> 16,
fcopy_srv_version & 0xFFFF);
}
} 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.recv_len = recvlen;
fcopy_transaction.recv_req_id = requestid;
fcopy_transaction.fcopy_msg = fcopy_msg;
if (fcopy_transaction.state < HVUTIL_READY) {
/* Userspace is not registered yet */
fcopy_respond_to_host(HV_E_FAIL);
return;
}
fcopy_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
/*
* Send the information to the user-level daemon.
*/
schedule_work(&fcopy_send_work);
schedule_delayed_work(&fcopy_timeout_work,
HV_UTIL_TIMEOUT * HZ);
return;
}
icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
VM_PKT_DATA_INBAND, 0);
}
/* Callback when data is received from userspace */
static int fcopy_on_msg(void *msg, int len)
{
int *val = (int *)msg;
if (len != sizeof(int))
return -EINVAL;
if (fcopy_transaction.state == HVUTIL_DEVICE_INIT)
return fcopy_handle_handshake(*val);
if (fcopy_transaction.state != HVUTIL_USERSPACE_REQ)
return -EINVAL;
/*
* Complete the transaction by forwarding the result
* to the host. But first, cancel the timeout.
*/
if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
fcopy_transaction.state = HVUTIL_USERSPACE_RECV;
fcopy_respond_to_host(*val);
hv_poll_channel(fcopy_transaction.recv_channel,
fcopy_poll_wrapper);
}
return 0;
}
static void fcopy_on_reset(void)
{
/*
* The daemon has exited; reset the state.
*/
fcopy_transaction.state = HVUTIL_DEVICE_INIT;
if (cancel_delayed_work_sync(&fcopy_timeout_work))
fcopy_respond_to_host(HV_E_FAIL);
}
int hv_fcopy_init(struct hv_util_service *srv)
{
recv_buffer = srv->recv_buffer;
fcopy_transaction.recv_channel = srv->channel;
/*
* 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.state = HVUTIL_DEVICE_INIT;
hvt = hvutil_transport_init(fcopy_devname, 0, 0,
fcopy_on_msg, fcopy_on_reset);
if (!hvt)
return -EFAULT;
return 0;
}
static void hv_fcopy_cancel_work(void)
{
cancel_delayed_work_sync(&fcopy_timeout_work);
cancel_work_sync(&fcopy_send_work);
}
int hv_fcopy_pre_suspend(void)
{
struct vmbus_channel *channel = fcopy_transaction.recv_channel;
struct hv_fcopy_hdr *fcopy_msg;
/*
* Fake a CANCEL_FCOPY message for the user space daemon in case the
* daemon is in the middle of copying some file. It doesn't matter if
* there is already a message pending to be delivered to the user
* space since we force fcopy_transaction.state to be HVUTIL_READY, so
* the user space daemon's write() will fail with EINVAL (see
* fcopy_on_msg()), and the daemon will reset the device by closing
* and re-opening it.
*/
fcopy_msg = kzalloc(sizeof(*fcopy_msg), GFP_KERNEL);
if (!fcopy_msg)
return -ENOMEM;
tasklet_disable(&channel->callback_event);
fcopy_msg->operation = CANCEL_FCOPY;
hv_fcopy_cancel_work();
/* We don't care about the return value. */
hvutil_transport_send(hvt, fcopy_msg, sizeof(*fcopy_msg), NULL);
kfree(fcopy_msg);
fcopy_transaction.state = HVUTIL_READY;
/* tasklet_enable() will be called in hv_fcopy_pre_resume(). */
return 0;
}
int hv_fcopy_pre_resume(void)
{
struct vmbus_channel *channel = fcopy_transaction.recv_channel;
tasklet_enable(&channel->callback_event);
return 0;
}
void hv_fcopy_deinit(void)
{
fcopy_transaction.state = HVUTIL_DEVICE_DYING;
hv_fcopy_cancel_work();
hvutil_transport_destroy(hvt);
}