From: Yicong Yang <yangyicong@hisilicon.com> driver inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBSI0M CVE: NA ---------------------------------------------------------------------- The BRBE support backported of v18 didn't configure the BRBCR_EL1 correctly which will miss some key functions like FZP during sampling. In VHE mode with MDCR_EL2.HPMN set to PMCR_EL0.N, the counters are controlled by BRBCR_EL1 rather than BRBCR_EL2 (which writes to BRBCR_EL1 are redirected to). Use the same value for both register except keep EL1 and EL0 recording disabled in guests. The fix is backported from the v19 version [1]. [1] https://lore.kernel.org/linux-arm-kernel/ 20250202-arm-brbe-v19-v19-0-1c1300802385@kernel.org/ T/#m887b1dcf7f6784b7293626952052f27b68784beb fixes: 6c6848e7e00c ("drivers: perf: arm_pmuv3: Enable branch stack sampling via FEAT_BRBE") Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> Signed-off-by: Qizhi Zhang <zhangqizhi3@h-partners.com> --- drivers/perf/arm_brbe.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/perf/arm_brbe.c b/drivers/perf/arm_brbe.c index d795e8fd646f..22e4828feec8 100644 --- a/drivers/perf/arm_brbe.c +++ b/drivers/perf/arm_brbe.c @@ -874,6 +874,16 @@ void armv8pmu_branch_enable(struct arm_pmu *arm_pmu) brbcr &= ~BRBCR_ELx_CONFIG_MASK; brbcr |= branch_type_to_brbcr(cpuc->branch_sample_type); write_sysreg_s(brbcr, SYS_BRBCR_EL1); + + /* + * In VHE mode with MDCR_EL2.HPMN set to PMCR_EL0.N, the counters are + * controlled by BRBCR_EL1 rather than BRBCR_EL2 (which writes to + * BRBCR_EL1 are redirected to). Use the same value for both register + * except keep EL1 and EL0 recording disabled in guests. + */ + if (is_kernel_in_hyp_mode()) + write_sysreg_s(brbcr & ~(BRBCR_ELx_ExBRE | BRBCR_ELx_E0BRE), SYS_BRBCR_EL12); + isb(); } @@ -886,6 +896,11 @@ void armv8pmu_branch_disable(void) brbcr &= ~(BRBCR_ELx_E0BRE | BRBCR_ELx_ExBRE); brbfcr |= BRBFCR_EL1_PAUSED; write_sysreg_s(brbcr, SYS_BRBCR_EL1); + + /* See the comment in armv8pmu_branch_enable() */ + if (is_kernel_in_hyp_mode()) + write_sysreg_s(brbcr, SYS_BRBCR_EL12); + write_sysreg_s(brbfcr, SYS_BRBFCR_EL1); isb(); } -- 2.33.0