2.6.26-rc1

 virt

 kvm

diff --git a/virt/kvm/kvm_trace.c b/virt/kvm/kvm_trace.c
new file mode 100644
index 0000000..0e49547
--- /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, kvm_debugfs_dir,
+                   kt, &kvm_trace_lost_ops);
+   if (!kt->lost_file)
+      goto err;
+
+   kt->rchan = relay_open("trace", kvm_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;
+}