On 1/3/22 18:38, Richard Henderson wrote:
On 1/3/22 10:53 AM, Daniel Henrique Barboza wrote:pmu_update_summaries() is not considering the case where the PMU can be turned off (i.e. stop counting all events) if MMCR0_FC is set, regardless of the other frozen counter bits state. This use case was covered in the late pmc_get_event(), via the also gone pmc_is_inactive(), that would return an invalid event if MMCR0_FC was set. This use case is exercised by the back_to_back_ebbs_test Linux kernel selftests [1]. As it is today, after enabling EBB exceptions, the test will report an additional event-based branch being taken and will fail. Other tests, such as cycles_test.c, will report additional cycles being calculated in the counters because we're not freezing the PMU quick enough. Fix pmu_update_summaries() by keeping env->ins_cnt and env->cyc_cnt cleared when MMCR0_FC is set. [1] tools/testing/selftests/powerpc/pmu/ebb/back_to_back_ebbs_test.c Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com> --- target/ppc/power8-pmu.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/target/ppc/power8-pmu.c b/target/ppc/power8-pmu.c index 7fc7d91109..73713ca2a3 100644 --- a/target/ppc/power8-pmu.c +++ b/target/ppc/power8-pmu.c @@ -40,6 +40,10 @@ void pmu_update_summaries(CPUPPCState *env) int ins_cnt = 0; int cyc_cnt = 0; + if (mmcr0 & MMCR0_FC) { + goto hflags_calc; + } + if (!(mmcr0 & MMCR0_FC14) && mmcr1 != 0) { target_ulong sel; @@ -71,6 +75,7 @@ void pmu_update_summaries(CPUPPCState *env) ins_cnt |= !(mmcr0 & MMCR0_FC56) << 5; cyc_cnt |= !(mmcr0 & MMCR0_FC56) << 6; + hflags_calc:Good catch, but should be folded into patch 1 to avoid bisection breakage.
Fair point. Given that you have a suggestion in patch 5 as well I'll send a v3. Thanks, Daniel
r~
