commit 338b522ca43c ("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 generates a #GPF when restoring a value of MSR_LAST_BRANCH_FROM_* msrs that has sign extension (e.g. kernel addresses). This hw bug/quirk currently does not manifest in the context switch of LBR callstack mode because of a workaround for another LBR bug (bug in FREEZE_LBRS_ON_PMI, more details in second patch of this series). The workaround deactivates LBR callstack in kernel mode. The second and fourth patches in this series contain workarounds for the MSR_LAST_BRANCH_FROM_* hw bug/quirk. The third patch contains a trivial format fix for aesthetic uniformity. The last patch is not to be committed, but to test the fourth patch. It removes the effect of the FREEZE_LBRS_ON_PMI work-around by allowing LBR callstack for kernel addresses. This series is rebased at torvalds/linux/master . Changes in 2nd version: - Remove branch from quirk (as pointed by Peter Z.). - Format fixes. David Carrillo-Cisneros (5): perf/x86/intel: output LBR support statement after validation perf/x86/intel: fix for MSR_LAST_BRANCH_FROM_x bug when no TSX perf/x86/intel: trivial format and style fix perf/x86/intel: MSR_LAST_BRANCH_FROM_x quirk for ctx switch not required, used to test ctxsw, do not merge arch/x86/events/intel/core.c | 20 ++++++++++ arch/x86/events/intel/lbr.c | 90 ++++++++++++++++++++++++++++++++++++-------- arch/x86/events/perf_event.h | 2 + tools/perf/util/evsel.c | 17 +++++++-- 4 files changed, 111 insertions(+), 18 deletions(-) -- 2.8.0.rc3.226.g39d4020
