Subject: [PATCH v4 08/21] KVM: ARM64: Add reset and access handlers for PMXEVTYPER register

From: [email-masked] (Shannon Zhao)
Date: Tue, 3 Nov 2015 10:41:45 +0800

On 2015/11/3 4:54, Christopher Covington wrote:
> Hi Shannon,
> 
> On 10/30/2015 02:21 AM, Shannon Zhao wrote:
>> From: Shannon Zhao <[email-masked]>
>>
>> Since the reset value of PMXEVTYPER is UNKNOWN, use reset_unknown or
>> reset_unknown_cp15 for its reset handler. Add access handler which
>> emulates writing and reading PMXEVTYPER register. When writing to
>> PMXEVTYPER, call kvm_pmu_set_counter_event_type to create a perf_event
>> for the selected event type.
>>
>> Signed-off-by: Shannon Zhao <[email-masked]>
>> ---
>>  arch/arm64/kvm/sys_regs.c | 26 ++++++++++++++++++++++++--
>>  1 file changed, 24 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index cb82b15..4e606ea 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -491,6 +491,17 @@ static bool access_pmu_regs(struct kvm_vcpu *vcpu,
>>  
>>  	if (p->is_write) {
>>  		switch (r->reg) {
>> +		case PMXEVTYPER_EL0: {
>> +			val = vcpu_sys_reg(vcpu, PMSELR_EL0);
>> +			kvm_pmu_set_counter_event_type(vcpu,
>> +						       *vcpu_reg(vcpu, p->Rt),
>> +						       val);
>> +			vcpu_sys_reg(vcpu, PMXEVTYPER_EL0) =
>> +							 *vcpu_reg(vcpu, p->Rt);
> 
> Why does PMXEVTYPER get set directly? It seems like it could have an accessor
> that redirected to PMEVTYPER<n>.
> 
Yeah, that's what this patch does. It gets the counter index from
PMSELR_EL0 register, then set the event type, create perf_event, store
event type to PMEVTYPER<n>, etc.

>> +			vcpu_sys_reg(vcpu, PMEVTYPER0_EL0 + val) =
>> +							 *vcpu_reg(vcpu, p->Rt);
> 
> I tried to look around briefly but couldn't find counter number range checking
> in the PMSELR handler or here. Should there be some here and in PMXEVCNTR?
> 
Ok, will fix this. Thanks.

-- 
Shannon