On 2015/10/16 23:06, Wei Huang wrote:
>
>
> On 09/24/2015 05:31 PM, Shannon Zhao wrote:
>> Since the reset value of PMCCNTR is UNKNOWN, use reset_unknown for its
>> reset handler. Add a new case to emulate reading to PMCCNTR register.
>>
>> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>> ---
>> arch/arm64/kvm/sys_regs.c | 17 +++++++++++++++--
>> 1 file changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index e7f6058..c38c2de 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -518,6 +518,12 @@ static bool access_pmu_regs(struct kvm_vcpu *vcpu,
>> }
>> } else {
>> switch (r->reg) {
>> + case PMCCNTR_EL0: {
>> + val = kvm_pmu_get_counter_value(vcpu,
>> + ARMV8_MAX_COUNTERS - 1);
>> + *vcpu_reg(vcpu, p->Rt) = val;
>> + break;
>> + }
>> case PMXEVCNTR_EL0: {
>> val = kvm_pmu_get_counter_value(vcpu,
>> vcpu_sys_reg(vcpu, PMSELR_EL0));
>> @@ -748,7 +754,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>> access_pmu_regs, reset_pmceid, PMCEID1_EL0 },
>> /* PMCCNTR_EL0 */
>> { Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1101), Op2(0b000),
>> - trap_raz_wi },
>> + access_pmu_regs, reset_unknown, PMCCNTR_EL0 },
>> /* PMXEVTYPER_EL0 */
>> { Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1101), Op2(0b001),
>> access_pmu_regs, reset_unknown, PMXEVTYPER_EL0 },
>> @@ -997,6 +1003,12 @@ static bool access_pmu_cp15_regs(struct kvm_vcpu *vcpu,
>> }
>> } else {
>> switch (r->reg) {
>> + case c9_PMCCNTR: {
>> + val = kvm_pmu_get_counter_value(vcpu,
>> + ARMV8_MAX_COUNTERS - 1);
>
> PMCCNTR is for cycle counter. There is a filter register, PMCCFILTR_EL0,
> associated with it. When kvm_pmu_set_counter_event_type() is called, I
> didn't see this filter config been used in perf_event_attr when
> perf_event is created.
According to the spec, to PMXEVTYPER_EL0 it says "When PMSELR_EL0.SEL
selects the cycle counter, this accesses PMCCFILTR_EL0." So within
kvm_pmu_set_counter_event_type, I configure the perf_event_attr based on
the bits of PMXEVTYPER_EL0 and only handle bit P for EL0 and bit U for
EL1 since KVM guest doesn't see EL2 and EL3.
See patch 07/20 :
+ attr.exclude_user = data & ARMV8_EXCLUDE_EL0 ? 1 : 0;
+ attr.exclude_kernel = data & ARMV8_EXCLUDE_EL1 ? 1 : 0;
--
Shannon
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