| Message ID | 20230921185445.3339214-1-peter.maydell@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | target/arm: Implement FEAT_HPMN0 | expand |
On 9/21/23 14:54, Peter Maydell wrote: > FEAT_HPMN0 is a small feature which defines that it is valid for > MDCR_EL2.HPMN to be set to 0, meaning "no PMU event counters provided > to an EL1 guest" (previously this setting was reserved). QEMU's > implementation almost gets HPMN == 0 right, but we need to fix > one check in pmevcntr_is_64_bit(). That is enough for us to > advertise the feature in the 'max' CPU. > > (We don't need to make the behaviour conditional on feature > presence, because the FEAT_HPMN0 behaviour is within the range > of permitted UNPREDICTABLE behaviour for a non-FEAT_HPMN0 > implementation.) > > Signed-off-by: Peter Maydell<peter.maydell@linaro.org> > --- > docs/system/arm/emulation.rst | 1 + > target/arm/helper.c | 2 +- > target/arm/tcg/cpu32.c | 4 ++++ > target/arm/tcg/cpu64.c | 1 + > 4 files changed, 7 insertions(+), 1 deletion(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/docs/system/arm/emulation.rst b/docs/system/arm/emulation.rst index 3df936fc356..b19ea198c24 100644 --- a/docs/system/arm/emulation.rst +++ b/docs/system/arm/emulation.rst @@ -45,6 +45,7 @@ the following architecture extensions: - FEAT_HCX (Support for the HCRX_EL2 register) - FEAT_HPDS (Hierarchical permission disables) - FEAT_HPDS2 (Translation table page-based hardware attributes) +- FEAT_HPMN0 (Setting of MDCR_EL2.HPMN to zero) - FEAT_I8MM (AArch64 Int8 matrix multiplication instructions) - FEAT_IDST (ID space trap handling) - FEAT_IESB (Implicit error synchronization event) diff --git a/target/arm/helper.c b/target/arm/helper.c index 3b22596eabf..ea3e5c6fd0f 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -1283,7 +1283,7 @@ static bool pmevcntr_is_64_bit(CPUARMState *env, int counter) bool hlp = env->cp15.mdcr_el2 & MDCR_HLP; int hpmn = env->cp15.mdcr_el2 & MDCR_HPMN; - if (hpmn != 0 && counter >= hpmn) { + if (counter >= hpmn) { return hlp; } } diff --git a/target/arm/tcg/cpu32.c b/target/arm/tcg/cpu32.c index 1f918ff5375..0d5d8e307dd 100644 --- a/target/arm/tcg/cpu32.c +++ b/target/arm/tcg/cpu32.c @@ -89,6 +89,10 @@ void aa32_max_features(ARMCPU *cpu) t = FIELD_DP32(t, ID_DFR0, COPSDBG, 9); /* FEAT_Debugv8p4 */ t = FIELD_DP32(t, ID_DFR0, PERFMON, 6); /* FEAT_PMUv3p5 */ cpu->isar.id_dfr0 = t; + + t = cpu->isar.id_dfr1; + t = FIELD_DP32(t, ID_DFR1, HPMN0, 1); /* FEAT_HPMN0 */ + cpu->isar.id_dfr1 = t; } /* CPU models. These are not needed for the AArch64 linux-user build. */ diff --git a/target/arm/tcg/cpu64.c b/target/arm/tcg/cpu64.c index 7264ab5ead1..ee369f10db6 100644 --- a/target/arm/tcg/cpu64.c +++ b/target/arm/tcg/cpu64.c @@ -1104,6 +1104,7 @@ void aarch64_max_tcg_initfn(Object *obj) t = cpu->isar.id_aa64dfr0; t = FIELD_DP64(t, ID_AA64DFR0, DEBUGVER, 9); /* FEAT_Debugv8p4 */ t = FIELD_DP64(t, ID_AA64DFR0, PMUVER, 6); /* FEAT_PMUv3p5 */ + t = FIELD_DP64(t, ID_AA64DFR0, HPMN0, 1); /* FEAT_HPMN0 */ cpu->isar.id_aa64dfr0 = t; t = cpu->isar.id_aa64smfr0;
FEAT_HPMN0 is a small feature which defines that it is valid for MDCR_EL2.HPMN to be set to 0, meaning "no PMU event counters provided to an EL1 guest" (previously this setting was reserved). QEMU's implementation almost gets HPMN == 0 right, but we need to fix one check in pmevcntr_is_64_bit(). That is enough for us to advertise the feature in the 'max' CPU. (We don't need to make the behaviour conditional on feature presence, because the FEAT_HPMN0 behaviour is within the range of permitted UNPREDICTABLE behaviour for a non-FEAT_HPMN0 implementation.) Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- docs/system/arm/emulation.rst | 1 + target/arm/helper.c | 2 +- target/arm/tcg/cpu32.c | 4 ++++ target/arm/tcg/cpu64.c | 1 + 4 files changed, 7 insertions(+), 1 deletion(-)