kvm-all: add kvm_ioctl, kvm_vm_ioctl, kvm_vcpu_ioctl tracepoints

This patch adds tracepoints at ioctl to kvm. Tracing these ioctl is
useful for clarification whether the cause of troubles is qemu or kvm.

Signed-off-by: Kazuya Saito <saito.kazuya@jp.fujitsu.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
kvm-all: add kvm_run_exit tracepoint

This patch enable us to know exit reason of KVM_RUN. It will help us
know where the trouble is caused.

Signed-off-by: Kazuya Saito <saito.kazuya@jp.fujitsu.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
trace: Add ftrace tracing backend

This patch adds a ftrace tracing backend which sends trace event to
ftrace marker file. You can effectively compare qemu trace data and
kernel(especially, kvm.ko when using KVM) trace data.
The ftrace backend is restricted to Linux only.

To try out the ftrace backend:

 $ ./configure --trace-backend=ftrace
 $ make

if you use KVM, enable kvm events in ftrace:

 # sudo echo 1 > /sys/kernel/debug/tracing/events/kvm/enable

After running qemu by root user, you can get the trace:

 # cat /sys/kernel/debug/tracing/trace

Signed-off-by: Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
trace: document ftrace backend

Add documentation of ftrace backend.

Signed-off-by: Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>