diff options
Diffstat (limited to 'virt/kvm/kvm_trace.c')
| -rw-r--r-- | virt/kvm/kvm_trace.c | 276 |
1 files changed, 276 insertions, 0 deletions
diff --git a/virt/kvm/kvm_trace.c b/virt/kvm/kvm_trace.c new file mode 100644 index 0000000..5425440 --- /dev/null +++ b/virt/kvm/kvm_trace.c @@ -0,0 +1,276 @@ +/* + * kvm trace + * + * It is designed to allow debugging traces of kvm to be generated + * on UP / SMP machines. Each trace entry can be timestamped so that + * it's possible to reconstruct a chronological record of trace events. + * The implementation refers to blktrace kernel support. + * + * Copyright (c) 2008 Intel Corporation + * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk> + * + * Authors: Feng(Eric) Liu, eric.e.liu@intel.com + * + * Date: Feb 2008 + */ + +#include <linux/module.h> +#include <linux/relay.h> +#include <linux/debugfs.h> + +#include <linux/kvm_host.h> + +#define KVM_TRACE_STATE_RUNNING (1 << 0) +#define KVM_TRACE_STATE_PAUSE (1 << 1) +#define KVM_TRACE_STATE_CLEARUP (1 << 2) + +struct kvm_trace { + int trace_state; + struct rchan *rchan; + struct dentry *lost_file; + atomic_t lost_records; +}; +static struct kvm_trace *kvm_trace; + +struct kvm_trace_probe { + const char *name; + const char *format; + u32 cycle_in; + marker_probe_func *probe_func; +}; + +static inline int calc_rec_size(int cycle, int extra) +{ + int rec_size = KVM_TRC_HEAD_SIZE; + + rec_size += extra; + return cycle ? rec_size += KVM_TRC_CYCLE_SIZE : rec_size; +} + +static void kvm_add_trace(void *probe_private, void *call_data, + const char *format, va_list *args) +{ + struct kvm_trace_probe *p = probe_private; + struct kvm_trace *kt = kvm_trace; + struct kvm_trace_rec rec; + struct kvm_vcpu *vcpu; + int i, extra, size; + + if (unlikely(kt->trace_state != KVM_TRACE_STATE_RUNNING)) + return; + + rec.event = va_arg(*args, u32); + vcpu = va_arg(*args, struct kvm_vcpu *); + rec.pid = current->tgid; + rec.vcpu_id = vcpu->vcpu_id; + + extra = va_arg(*args, u32); + WARN_ON(!(extra <= KVM_TRC_EXTRA_MAX)); + extra = min_t(u32, extra, KVM_TRC_EXTRA_MAX); + rec.extra_u32 = extra; + + rec.cycle_in = p->cycle_in; + + if (rec.cycle_in) { + u64 cycle = 0; + + cycle = get_cycles(); + rec.u.cycle.cycle_lo = (u32)cycle; + rec.u.cycle.cycle_hi = (u32)(cycle >> 32); + + for (i = 0; i < rec.extra_u32; i++) + rec.u.cycle.extra_u32[i] = va_arg(*args, u32); + } else { + for (i = 0; i < rec.extra_u32; i++) + rec.u.nocycle.extra_u32[i] = va_arg(*args, u32); + } + + size = calc_rec_size(rec.cycle_in, rec.extra_u32 * sizeof(u32)); + relay_write(kt->rchan, &rec, size); +} + +static struct kvm_trace_probe kvm_trace_probes[] = { + { "kvm_trace_entryexit", "%u %p %u %u %u %u %u %u", 1, kvm_add_trace }, + { "kvm_trace_handler", "%u %p %u %u %u %u %u %u", 0, kvm_add_trace }, +}; + +static int lost_records_get(void *data, u64 *val) +{ + struct kvm_trace *kt = data; + + *val = atomic_read(&kt->lost_records); + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(kvm_trace_lost_ops, lost_records_get, NULL, "%llu\n"); + +/* + * The relay channel is used in "no-overwrite" mode, it keeps trace of how + * many times we encountered a full subbuffer, to tell user space app the + * lost records there were. + */ +static int kvm_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, + void *prev_subbuf, size_t prev_padding) +{ + struct kvm_trace *kt; + + if (!relay_buf_full(buf)) + return 1; + + kt = buf->chan->private_data; + atomic_inc(&kt->lost_records); + + return 0; +} + +static struct dentry *kvm_create_buf_file_callack(const char *filename, + struct dentry *parent, + int mode, + struct rchan_buf *buf, + int *is_global) +{ + return debugfs_create_file(filename, mode, parent, buf, + &relay_file_operations); +} + +static int kvm_remove_buf_file_callback(struct dentry *dentry) +{ + debugfs_remove(dentry); + return 0; +} + +static struct rchan_callbacks kvm_relay_callbacks = { + .subbuf_start = kvm_subbuf_start_callback, + .create_buf_file = kvm_create_buf_file_callack, + .remove_buf_file = kvm_remove_buf_file_callback, +}; + +static int do_kvm_trace_enable(struct kvm_user_trace_setup *kuts) +{ + struct kvm_trace *kt; + int i, r = -ENOMEM; + + if (!kuts->buf_size || !kuts->buf_nr) + return -EINVAL; + + kt = kzalloc(sizeof(*kt), GFP_KERNEL); + if (!kt) + goto err; + + r = -EIO; + atomic_set(&kt->lost_records, 0); + kt->lost_file = debugfs_create_file("lost_records", 0444, debugfs_dir, + kt, &kvm_trace_lost_ops); + if (!kt->lost_file) + goto err; + + kt->rchan = relay_open("trace", debugfs_dir, kuts->buf_size, + kuts->buf_nr, &kvm_relay_callbacks, kt); + if (!kt->rchan) + goto err; + + kvm_trace = kt; + + for (i = 0; i < ARRAY_SIZE(kvm_trace_probes); i++) { + struct kvm_trace_probe *p = &kvm_trace_probes[i]; + + r = marker_probe_register(p->name, p->format, p->probe_func, p); + if (r) + printk(KERN_INFO "Unable to register probe %s\n", + p->name); + } + + kvm_trace->trace_state = KVM_TRACE_STATE_RUNNING; + + return 0; +err: + if (kt) { + if (kt->lost_file) + debugfs_remove(kt->lost_file); + if (kt->rchan) + relay_close(kt->rchan); + kfree(kt); + } + return r; +} + +static int kvm_trace_enable(char __user *arg) +{ + struct kvm_user_trace_setup kuts; + int ret; + + ret = copy_from_user(&kuts, arg, sizeof(kuts)); + if (ret) + return -EFAULT; + + ret = do_kvm_trace_enable(&kuts); + if (ret) + return ret; + + return 0; +} + +static int kvm_trace_pause(void) +{ + struct kvm_trace *kt = kvm_trace; + int r = -EINVAL; + + if (kt == NULL) + return r; + + if (kt->trace_state == KVM_TRACE_STATE_RUNNING) { + kt->trace_state = KVM_TRACE_STATE_PAUSE; + relay_flush(kt->rchan); + r = 0; + } + + return r; +} + +void kvm_trace_cleanup(void) +{ + struct kvm_trace *kt = kvm_trace; + int i; + + if (kt == NULL) + return; + + if (kt->trace_state == KVM_TRACE_STATE_RUNNING || + kt->trace_state == KVM_TRACE_STATE_PAUSE) { + + kt->trace_state = KVM_TRACE_STATE_CLEARUP; + + for (i = 0; i < ARRAY_SIZE(kvm_trace_probes); i++) { + struct kvm_trace_probe *p = &kvm_trace_probes[i]; + marker_probe_unregister(p->name, p->probe_func, p); + } + + relay_close(kt->rchan); + debugfs_remove(kt->lost_file); + kfree(kt); + } +} + +int kvm_trace_ioctl(unsigned int ioctl, unsigned long arg) +{ + void __user *argp = (void __user *)arg; + long r = -EINVAL; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + switch (ioctl) { + case KVM_TRACE_ENABLE: + r = kvm_trace_enable(argp); + break; + case KVM_TRACE_PAUSE: + r = kvm_trace_pause(); + break; + case KVM_TRACE_DISABLE: + r = 0; + kvm_trace_cleanup(); + break; + } + + return r; +} |
