perf/x86/intel/pt: Handle VMX better

perf/x86/intel/pt: Handle VMX better

Since commit:

  1c5ac21a0e ("perf/x86/intel/pt: Don't die on VMXON")

... PT events depend on re-scheduling to get enabled after a VMX session
has taken place. This is, in particular, a problem for CPU context events,
which don't normally get re-scheduled, unless there is a reason.

This patch changes the VMX handling so that PT event gets re-enabled
when VMX root mode exits.

Also, notify the user when there's a gap in PT data due to VMX root
mode by flagging AUX records as partial.

In combination with vmm_exclusive=0 parameter of the kvm_intel driver,
this will result in trace gaps only for the duration of the guest's
timeslices.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20170220133352.17995-5-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>