2
0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-25 05:34:00 +08:00
linux-next/drivers/hv/hv_fcopy.c
Andrea Parri (Microsoft) 238d2ed8f7 hv_utils: Always execute the fcopy and vss callbacks in a tasklet
The fcopy and vss callback functions could be running in a tasklet
at the same time they are called in hv_poll_channel().  Current code
serializes the invocations of these functions, and their accesses to
the channel ring buffer, by sending an IPI to the CPU that is allowed
to access the ring buffer, cf. hv_poll_channel().  This IPI mechanism
becomes infeasible if we allow changing the CPU that a channel will
interrupt.  Instead modify the callback wrappers to always execute
the fcopy and vss callbacks in a tasklet, thus mirroring the solution
for the kvp callback functions adopted since commit a3ade8cc47
("HV: properly delay KVP packets when negotiation is in progress").
This will ensure that the callback function can't run on two CPUs at
the same time.

Suggested-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200406001514.19876-6-parri.andrea@gmail.com
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
2020-04-23 13:17:11 +00:00

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;
tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event);
}
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);
}