qemu/os-posix.c
Satoru Moriya 888a6bc63c Add option to mlock qemu and guest memory
In certain scenario, latency induced by paging is significant and
memory locking is needed. Also, in the scenario with untrusted
guests, latency improvement due to mlock is desired.

This patch introduces a following new option to mlock guest and
qemu memory:

-realtime mlock=on|off

Signed-off-by: Satoru Moriya <satoru.moriya@hds.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1366382526-26146-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-04-22 08:52:23 -05:00

378 lines
8.5 KiB
C

/*
* os-posix.c
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2010 Red Hat, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
/*needed for MAP_POPULATE before including qemu-options.h */
#include <sys/mman.h>
#include <pwd.h>
#include <grp.h>
#include <libgen.h>
/* Needed early for CONFIG_BSD etc. */
#include "config-host.h"
#include "sysemu/sysemu.h"
#include "net/slirp.h"
#include "qemu-options.h"
#ifdef CONFIG_LINUX
#include <sys/prctl.h>
#endif
#ifdef __FreeBSD__
#include <sys/sysctl.h>
#endif
static struct passwd *user_pwd;
static const char *chroot_dir;
static int daemonize;
static int fds[2];
void os_setup_early_signal_handling(void)
{
struct sigaction act;
sigfillset(&act.sa_mask);
act.sa_flags = 0;
act.sa_handler = SIG_IGN;
sigaction(SIGPIPE, &act, NULL);
}
static void termsig_handler(int signal, siginfo_t *info, void *c)
{
qemu_system_killed(info->si_signo, info->si_pid);
}
void os_setup_signal_handling(void)
{
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_sigaction = termsig_handler;
act.sa_flags = SA_SIGINFO;
sigaction(SIGINT, &act, NULL);
sigaction(SIGHUP, &act, NULL);
sigaction(SIGTERM, &act, NULL);
}
/* Find a likely location for support files using the location of the binary.
For installed binaries this will be "$bindir/../share/qemu". When
running from the build tree this will be "$bindir/../pc-bios". */
#define SHARE_SUFFIX "/share/qemu"
#define BUILD_SUFFIX "/pc-bios"
char *os_find_datadir(const char *argv0)
{
char *dir;
char *p = NULL;
char *res;
char buf[PATH_MAX];
size_t max_len;
#if defined(__linux__)
{
int len;
len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
if (len > 0) {
buf[len] = 0;
p = buf;
}
}
#elif defined(__FreeBSD__)
{
static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
size_t len = sizeof(buf) - 1;
*buf = '\0';
if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
*buf) {
buf[sizeof(buf) - 1] = '\0';
p = buf;
}
}
#endif
/* If we don't have any way of figuring out the actual executable
location then try argv[0]. */
if (!p) {
p = realpath(argv0, buf);
if (!p) {
return NULL;
}
}
dir = dirname(p);
dir = dirname(dir);
max_len = strlen(dir) +
MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
res = g_malloc0(max_len);
snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
if (access(res, R_OK)) {
snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
if (access(res, R_OK)) {
g_free(res);
res = NULL;
}
}
return res;
}
#undef SHARE_SUFFIX
#undef BUILD_SUFFIX
void os_set_proc_name(const char *s)
{
#if defined(PR_SET_NAME)
char name[16];
if (!s)
return;
pstrcpy(name, sizeof(name), s);
/* Could rewrite argv[0] too, but that's a bit more complicated.
This simple way is enough for `top'. */
if (prctl(PR_SET_NAME, name)) {
perror("unable to change process name");
exit(1);
}
#else
fprintf(stderr, "Change of process name not supported by your OS\n");
exit(1);
#endif
}
/*
* Parse OS specific command line options.
* return 0 if option handled, -1 otherwise
*/
void os_parse_cmd_args(int index, const char *optarg)
{
switch (index) {
#ifdef CONFIG_SLIRP
case QEMU_OPTION_smb:
if (net_slirp_smb(optarg) < 0)
exit(1);
break;
#endif
case QEMU_OPTION_runas:
user_pwd = getpwnam(optarg);
if (!user_pwd) {
fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
exit(1);
}
break;
case QEMU_OPTION_chroot:
chroot_dir = optarg;
break;
case QEMU_OPTION_daemonize:
daemonize = 1;
break;
#if defined(CONFIG_LINUX)
case QEMU_OPTION_enablefips:
fips_set_state(true);
break;
#endif
}
}
static void change_process_uid(void)
{
if (user_pwd) {
if (setgid(user_pwd->pw_gid) < 0) {
fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
exit(1);
}
if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
user_pwd->pw_name, user_pwd->pw_gid);
exit(1);
}
if (setuid(user_pwd->pw_uid) < 0) {
fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
exit(1);
}
if (setuid(0) != -1) {
fprintf(stderr, "Dropping privileges failed\n");
exit(1);
}
}
}
static void change_root(void)
{
if (chroot_dir) {
if (chroot(chroot_dir) < 0) {
fprintf(stderr, "chroot failed\n");
exit(1);
}
if (chdir("/")) {
perror("not able to chdir to /");
exit(1);
}
}
}
void os_daemonize(void)
{
if (daemonize) {
pid_t pid;
if (pipe(fds) == -1)
exit(1);
pid = fork();
if (pid > 0) {
uint8_t status;
ssize_t len;
close(fds[1]);
again:
len = read(fds[0], &status, 1);
if (len == -1 && (errno == EINTR))
goto again;
if (len != 1)
exit(1);
else if (status == 1) {
fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno));
exit(1);
} else
exit(0);
} else if (pid < 0)
exit(1);
close(fds[0]);
qemu_set_cloexec(fds[1]);
setsid();
pid = fork();
if (pid > 0)
exit(0);
else if (pid < 0)
exit(1);
umask(027);
signal(SIGTSTP, SIG_IGN);
signal(SIGTTOU, SIG_IGN);
signal(SIGTTIN, SIG_IGN);
}
}
void os_setup_post(void)
{
int fd = 0;
if (daemonize) {
uint8_t status = 0;
ssize_t len;
again1:
len = write(fds[1], &status, 1);
if (len == -1 && (errno == EINTR))
goto again1;
if (len != 1)
exit(1);
if (chdir("/")) {
perror("not able to chdir to /");
exit(1);
}
TFR(fd = qemu_open("/dev/null", O_RDWR));
if (fd == -1)
exit(1);
}
change_root();
change_process_uid();
if (daemonize) {
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
close(fd);
}
}
void os_pidfile_error(void)
{
if (daemonize) {
uint8_t status = 1;
if (write(fds[1], &status, 1) != 1) {
perror("daemonize. Writing to pipe\n");
}
} else
fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
}
void os_set_line_buffering(void)
{
setvbuf(stdout, NULL, _IOLBF, 0);
}
int qemu_create_pidfile(const char *filename)
{
char buffer[128];
int len;
int fd;
fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
if (fd == -1) {
return -1;
}
if (lockf(fd, F_TLOCK, 0) == -1) {
close(fd);
return -1;
}
len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
if (write(fd, buffer, len) != len) {
close(fd);
return -1;
}
/* keep pidfile open & locked forever */
return 0;
}
bool is_daemonized(void)
{
return daemonize;
}
int os_mlock(void)
{
int ret = 0;
ret = mlockall(MCL_CURRENT | MCL_FUTURE);
if (ret < 0) {
perror("mlockall");
}
return ret;
}