In kvm_stat we grovel through /sys to find out how many cpus are in the
system. However if a cpu is offline it will still be present in /sys,
and the perf_event_open() will fail.

Modify the logic to only return online cpus. We need to be careful on
systems which don't support cpu hotplug, the online file will not be
present at all.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The old stats contain information not available in the tracepoints.
By default, keep the old behavior, but allow choosing which set of stats
to present, or even both.

Inspired by a patch from Marcelo Tosatti.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Correct sys_perf_event_open syscall number for s390 architecture
   - the hardcoded syscall number 298 is for x86 but should
     be different for other architectures.
     In case we figure out via /proc/cpuinfo that we are running
     on s390 the appropriate syscall number is used from map
     syscall_numbers; other architectures can extend this.
Signed-off-by: NHeinz Graalfs <graalfs@linux.vnet.ibm.com>
Signed-off-by: NJens Freimann <jfrei@linux.vnet.ibm.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Add s390_exit_reasons so kvm_stat doesn't crash when called on s390.
Look for 'vendor_id' in /proc/cpuinfo as well, instead of just for
'flags', so we can determine if we run on S390.
Signed-off-by: NJens Freimann <jfrei@linux.vnet.ibm.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Taken from original qemu-kvm/kvm/kvm_stat.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>