qemu/hw/remote/mpqemu-link.c
Stefan Hajnoczi a4a411fbaf Replace "iothread lock" with "BQL" in comments
The term "iothread lock" is obsolete. The APIs use Big QEMU Lock (BQL)
in their names. Update the code comments to use "BQL" instead of
"iothread lock".

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Message-id: 20240102153529.486531-5-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2024-01-08 10:45:43 -05:00

264 lines
6.7 KiB
C

/*
* Communication channel between QEMU and remote device process
*
* Copyright © 2018, 2021 Oracle and/or its affiliates.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qemu/module.h"
#include "hw/remote/mpqemu-link.h"
#include "qapi/error.h"
#include "qemu/iov.h"
#include "qemu/error-report.h"
#include "qemu/main-loop.h"
#include "io/channel.h"
#include "sysemu/iothread.h"
#include "trace.h"
/*
* Send message over the ioc QIOChannel.
* This function is safe to call from:
* - main loop in co-routine context. Will block the main loop if not in
* co-routine context;
* - vCPU thread with no co-routine context and if the channel is not part
* of the main loop handling;
* - IOThread within co-routine context, outside of co-routine context
* will block IOThread;
* Returns true if no errors were encountered, false otherwise.
*/
bool mpqemu_msg_send(MPQemuMsg *msg, QIOChannel *ioc, Error **errp)
{
bool drop_bql = bql_locked();
bool iothread = qemu_in_iothread();
struct iovec send[2] = {};
int *fds = NULL;
size_t nfds = 0;
bool ret = false;
send[0].iov_base = msg;
send[0].iov_len = MPQEMU_MSG_HDR_SIZE;
send[1].iov_base = (void *)&msg->data;
send[1].iov_len = msg->size;
if (msg->num_fds) {
nfds = msg->num_fds;
fds = msg->fds;
}
/*
* Dont use in IOThread out of co-routine context as
* it will block IOThread.
*/
assert(qemu_in_coroutine() || !iothread);
/*
* Skip unlocking/locking BQL when the IOThread is running
* in co-routine context. Co-routine context is asserted above
* for IOThread case.
* Also skip lock handling while in a co-routine in the main context.
*/
if (drop_bql && !iothread && !qemu_in_coroutine()) {
bql_unlock();
}
if (!qio_channel_writev_full_all(ioc, send, G_N_ELEMENTS(send),
fds, nfds, 0, errp)) {
ret = true;
} else {
trace_mpqemu_send_io_error(msg->cmd, msg->size, nfds);
}
if (drop_bql && !iothread && !qemu_in_coroutine()) {
/* See above comment why skip locking here. */
bql_lock();
}
return ret;
}
/*
* Read message from the ioc QIOChannel.
* This function is safe to call from:
* - From main loop in co-routine context. Will block the main loop if not in
* co-routine context;
* - From vCPU thread with no co-routine context and if the channel is not part
* of the main loop handling;
* - From IOThread within co-routine context, outside of co-routine context
* will block IOThread;
*/
static ssize_t mpqemu_read(QIOChannel *ioc, void *buf, size_t len, int **fds,
size_t *nfds, Error **errp)
{
struct iovec iov = { .iov_base = buf, .iov_len = len };
bool drop_bql = bql_locked();
bool iothread = qemu_in_iothread();
int ret = -1;
/*
* Dont use in IOThread out of co-routine context as
* it will block IOThread.
*/
assert(qemu_in_coroutine() || !iothread);
if (drop_bql && !iothread && !qemu_in_coroutine()) {
bql_unlock();
}
ret = qio_channel_readv_full_all_eof(ioc, &iov, 1, fds, nfds, errp);
if (drop_bql && !iothread && !qemu_in_coroutine()) {
bql_lock();
}
return (ret <= 0) ? ret : iov.iov_len;
}
bool mpqemu_msg_recv(MPQemuMsg *msg, QIOChannel *ioc, Error **errp)
{
ERRP_GUARD();
g_autofree int *fds = NULL;
size_t nfds = 0;
ssize_t len;
bool ret = false;
len = mpqemu_read(ioc, msg, MPQEMU_MSG_HDR_SIZE, &fds, &nfds, errp);
if (len <= 0) {
goto fail;
} else if (len != MPQEMU_MSG_HDR_SIZE) {
error_setg(errp, "Message header corrupted");
goto fail;
}
if (msg->size > sizeof(msg->data)) {
error_setg(errp, "Invalid size for message");
goto fail;
}
if (!msg->size) {
goto copy_fds;
}
len = mpqemu_read(ioc, &msg->data, msg->size, NULL, NULL, errp);
if (len <= 0) {
goto fail;
}
if (len != msg->size) {
error_setg(errp, "Unable to read full message");
goto fail;
}
copy_fds:
msg->num_fds = nfds;
if (nfds > G_N_ELEMENTS(msg->fds)) {
error_setg(errp,
"Overflow error: received %zu fds, more than max of %d fds",
nfds, REMOTE_MAX_FDS);
goto fail;
}
if (nfds) {
memcpy(msg->fds, fds, nfds * sizeof(int));
}
ret = true;
fail:
if (*errp) {
trace_mpqemu_recv_io_error(msg->cmd, msg->size, nfds);
}
while (*errp && nfds) {
close(fds[nfds - 1]);
nfds--;
}
return ret;
}
/*
* Send msg and wait for a reply with command code RET_MSG.
* Returns the message received of size u64 or UINT64_MAX
* on error.
* Called from VCPU thread in non-coroutine context.
* Used by the Proxy object to communicate to remote processes.
*/
uint64_t mpqemu_msg_send_and_await_reply(MPQemuMsg *msg, PCIProxyDev *pdev,
Error **errp)
{
MPQemuMsg msg_reply = {0};
uint64_t ret = UINT64_MAX;
assert(!qemu_in_coroutine());
QEMU_LOCK_GUARD(&pdev->io_mutex);
if (!mpqemu_msg_send(msg, pdev->ioc, errp)) {
return ret;
}
if (!mpqemu_msg_recv(&msg_reply, pdev->ioc, errp)) {
return ret;
}
if (!mpqemu_msg_valid(&msg_reply) || msg_reply.cmd != MPQEMU_CMD_RET) {
error_setg(errp, "ERROR: Invalid reply received for command %d",
msg->cmd);
return ret;
}
return msg_reply.data.u64;
}
bool mpqemu_msg_valid(MPQemuMsg *msg)
{
if (msg->cmd >= MPQEMU_CMD_MAX || msg->cmd < 0) {
return false;
}
/* Verify FDs. */
if (msg->num_fds >= REMOTE_MAX_FDS) {
return false;
}
if (msg->num_fds > 0) {
for (int i = 0; i < msg->num_fds; i++) {
if (fcntl(msg->fds[i], F_GETFL) == -1) {
return false;
}
}
}
/* Verify message specific fields. */
switch (msg->cmd) {
case MPQEMU_CMD_SYNC_SYSMEM:
if (msg->num_fds == 0 || msg->size != sizeof(SyncSysmemMsg)) {
return false;
}
break;
case MPQEMU_CMD_PCI_CFGWRITE:
case MPQEMU_CMD_PCI_CFGREAD:
if (msg->size != sizeof(PciConfDataMsg)) {
return false;
}
break;
case MPQEMU_CMD_BAR_WRITE:
case MPQEMU_CMD_BAR_READ:
if ((msg->size != sizeof(BarAccessMsg)) || (msg->num_fds != 0)) {
return false;
}
break;
case MPQEMU_CMD_SET_IRQFD:
if (msg->size || (msg->num_fds != 2)) {
return false;
}
break;
default:
break;
}
return true;
}