[PATCH 0/3] fix MSR_LAST_BRANCH_FROM Haswell support

[David Carrillo-Cisneros <davidcc@google.com>]

The patch:
perf/x86/intel: Protect LBR and extra_regs against KVM lying

introduced an extra test for LBR support but did not move the dmesg
accordingly. This problem is fixed in first patch in this series.

When a machine that used LBR is rebooted using kexec, the extra test
for LBR support may fail due to a hw bug/quirk in Haswell that generate
a #GPF when restoring the value of MSR_LAST_BRANCH_FROM_* msrs with
sign-extended valuse (e.p. kernel addresses).

During normal execution, this problem is masked by a work-around to
another hw bug that prevented FREEZE_LBRS_ON_PMI from be used in kernel
branches, introduced in
"perf/x86/intel: Add Haswell LBR call stack support".

The second patch in this series contains a workaround for the
MSR_LAST_BRANCH_FROM_* hw bug/quirk.

The last patch is not to be commited, but to test the second patch. It
removes the effect of the FREEZE_LBRS_ON_PMI work-around by allowing
LBR call-stack for kernel addresses.

This series is rebased at torvalds/linux/master .

David Carrillo-Cisneros (3):
  perf/x86/intel: output LBR support statement after validation
  perf/x86/intel: fix for MSR_LAST_BRANCH_FROM_x quirk when no TSX
  perf, perf/tool: trigger lbr_from signext bug

 arch/x86/events/intel/core.c | 20 +++++++++++
 arch/x86/events/intel/lbr.c  | 83 +++++++++++++++++++++++++++++++++++++-------
 arch/x86/events/perf_event.h |  2 ++
 tools/perf/util/evsel.c      | 17 +++++++--
 4 files changed, 106 insertions(+), 16 deletions(-)

-- 
2.8.0.rc3.226.g39d4020