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最新推荐文章于 2023-11-29 22:07:23 发布

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本文介绍了一个用于处理虚拟CPU在线状态的函数transfer_vcpu。该函数通过读写/sys/devices/system/cpu目录下的online文件来获取和设置指定逻辑处理器的在线状态。

static void transfer_vcpu(GuestLogicalProcessor *vcpu, bool sys2vcpu,
Error **errp)
{
char *dirpath;
int dirfd;

dirpath = g_strdup_printf("/sys/devices/system/cpu/cpu%" PRId64 "/",
vcpu->logical_id);
dirfd = open(dirpath, O_RDONLY | O_DIRECTORY);
if (dirfd == -1) {
error_setg_errno(errp, errno, "open(\"%s\")", dirpath);
} else {
static const char fn[] = "online";
int fd;
int res;

fd = openat(dirfd, fn, sys2vcpu ? O_RDONLY : O_RDWR);
if (fd == -1) {
if (errno != ENOENT) {
error_setg_errno(errp, errno, "open(\"%s/%s\")", dirpath, fn);
} else if (sys2vcpu) {
vcpu->online = true;
vcpu->can_offline = false;
} else if (!vcpu->online) {
error_setg(errp, "logical processor #%" PRId64 " can't be "
"offlined", vcpu->logical_id);
} /* otherwise pretend successful re-onlining */
} else {
unsigned char status;

res = pread(fd, &status, 1, 0);
if (res == -1) {
error_setg_errno(errp, errno, "pread(\"%s/%s\")", dirpath, fn);
} else if (res == 0) {
error_setg(errp, "pread(\"%s/%s\"): unexpected EOF", dirpath,
fn);
} else if (sys2vcpu) {
vcpu->online = (status != '0');
vcpu->can_offline = true;
} else if (vcpu->online != (status != '0')) {
status = '0' + vcpu->online;
if (pwrite(fd, &status, 1, 0) == -1) {
error_setg_errno(errp, errno, "pwrite(\"%s/%s\")", dirpath,
fn);
}
} /* otherwise pretend successful re-(on|off)-lining */

res = close(fd);
g_assert(res == 0);
}

res = close(dirfd);
g_assert(res == 0);
}

g_free(dirpath);
}