On 07/01/16 12:09, Shannon Zhao wrote:
>
>
> On 2015/12/22 16:08, Shannon Zhao wrote:
>> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>>
>> These kind of registers include PMEVTYPERn, PMCCFILTR and PMXEVTYPER
>> which is mapped to PMEVTYPERn or PMCCFILTR.
>>
>> The access handler translates all aarch32 register offsets to aarch64
>> ones and uses vcpu_sys_reg() to access their values to avoid taking care
>> of big endian.
>>
>> When writing to these registers, create a perf_event for the selected
>> event type.
>>
>> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>> ---
>> arch/arm64/kvm/sys_regs.c | 156 +++++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 154 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index 2552db1..ed2939b 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -505,6 +505,70 @@ static bool access_pmceid(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
>> return true;
>> }
>>
>> +static inline bool pmu_counter_idx_valid(struct kvm_vcpu *vcpu, u64 idx)
>> +{
>> + u64 pmcr, val;
>> +
>> + pmcr = vcpu_sys_reg(vcpu, PMCR_EL0);
>> + val = (pmcr >> ARMV8_PMCR_N_SHIFT) & ARMV8_PMCR_N_MASK;
>> + if (idx >= val && idx != ARMV8_CYCLE_IDX)
>> + return false;
>> +
>> + return true;
>> +}
>> +
>> +static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
>> + const struct sys_reg_desc *r)
>> +{
>> + u64 idx, reg;
>> +
>> + if (r->CRn == 9) {
>> + /* PMXEVTYPER_EL0 */
>> + reg = 0;
>> + } else {
>> + if (!p->is_aarch32) {
>> + /* PMEVTYPERn_EL0 or PMCCFILTR_EL0 */
>> + reg = r->reg;
>> + } else {
>> + if (r->CRn == 14 && r->CRm == 15 && r->Op2 == 7) {
>> + reg = PMCCFILTR_EL0;
>> + } else {
>> + reg = ((r->CRm & 3) << 3) | (r->Op2 & 7);
>> + reg += PMEVTYPER0_EL0;
>> + }
>> + }
>> + }
>> +
>> + switch (reg) {
>> + case PMEVTYPER0_EL0 ... PMEVTYPER30_EL0:
>> + idx = reg - PMEVTYPER0_EL0;
>> + if (!pmu_counter_idx_valid(vcpu, idx))
>> + return true;
> Hi Marc,
>
> Here should we return false to inject an UND since there is no
> PMEVTYPER(idx)_EL0? The ARMv8 spec says it should.
The spec says that the following behaviours are valid:
- Accesses to the register are UNDEFINED .
- Accesses to the register behave as RAZ/WI.
- Accesses to the register execute as a NOP .
Same for the counters. So you can either return true (act as a NOP), or
return false (UNDEF), and even zero r->regval on read and return true
(RAZ/WI).
This is entirely up to you. My personal preference is indeed to UNDEF,
but your current implementation is valid.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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