perf intel-pt: Amend decoder to track the NR flag

perf intel-pt: Amend decoder to track the NR flag

The PIP packet NR (non-root) flag indicates whether or not a virtual
machine is being traced (NR=1 => VM). Add support for tracking its value.

In particular note that the PIP packet (outside of PSB+) will be
associated with a TIP packet from which address the NR value takes
effect. At that point, there is a branch from_ip, to_ip with
corresponding from_nr and to_nr.

In the event of VM-Entry failure, there should still PIP and TIP packets
that can be followed in the same way.

Also note that this assumes that a host VMM is not employing VMX controls
that affect Intel PT, e.g. to hide the host from a guest using Intel PT.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210218095801.19576-5-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>