On Mon, Jul 06, 2015 at 10:17:41AM +0800, shannon.zhao@xxxxxxxxxx wrote:
> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>
> Since the reset value of PMCNTENSET_EL0 and PMCNTENCLR_EL0 is UNKNOWN,
> use reset_unknown for its reset handler. Add access handler which
> emulates writing and reading PMCNTENSET_EL0 or PMCNTENCLR_EL0 register.
> When writing to PMCNTENSET_EL0, call perf_event_enable to enable the
> perf event. When writing to PMCNTENCLR_EL0, call perf_event_disable to
> disable the perf event.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> ---
> arch/arm64/kvm/sys_regs.c | 56 +++++++++++++++++++++++++++++++++++++++++++++--
> include/kvm/arm_pmu.h | 4 ++++
> virt/kvm/arm/pmu.c | 41 ++++++++++++++++++++++++++++++++++
> 3 files changed, 99 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 29883df..c14ec8d 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -392,6 +392,58 @@ static bool access_pmccntr(struct kvm_vcpu *vcpu,
> return true;
> }
>
> +/* PMCNTENSET_EL0 accessor. */
> +static bool access_pmcntenset(struct kvm_vcpu *vcpu,
> + const struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + unsigned long val;
> +
> + if (p->is_write) {
> + val = *vcpu_reg(vcpu, p->Rt);
> + if (!p->is_aarch32)
> + vcpu_sys_reg(vcpu, r->reg) |= val;
> + else
> + vcpu_cp15(vcpu, r->reg) |= val & 0xffffffffUL;
> +
> + kvm_pmu_enable_counter(vcpu, val);
> + } else {
> + if (!p->is_aarch32)
> + val = vcpu_sys_reg(vcpu, r->reg);
> + else
> + val = vcpu_cp15(vcpu, r->reg);
> + *vcpu_reg(vcpu, p->Rt) = val;
> + }
> +
> + return true;
> +}
> +
> +/* PMCNTENCLR_EL0 accessor. */
> +static bool access_pmcntenclr(struct kvm_vcpu *vcpu,
> + const struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + unsigned long val;
> +
> + if (p->is_write) {
> + val = *vcpu_reg(vcpu, p->Rt);
> + if (!p->is_aarch32)
> + vcpu_sys_reg(vcpu, r->reg) |= val;
huh, this is the clear register, don't you need to &= ~val ?
also, there's a lot of code duplication between these two functions, it
must be worthwhile having a single static function that they both call
if a bool differentiating between set/clear.
> + else
> + vcpu_cp15(vcpu, r->reg) |= val & 0xffffffffUL;
> +
> + kvm_pmu_disable_counter(vcpu, val);
> + } else {
> + if (!p->is_aarch32)
> + val = vcpu_sys_reg(vcpu, r->reg);
> + else
> + val = vcpu_cp15(vcpu, r->reg);
> + *vcpu_reg(vcpu, p->Rt) = val;
> + }
> +
> + return true;
> +}
> +
> /* Silly macro to expand the DBG{BCR,BVR,WVR,WCR}n_EL1 registers in one go */
> #define DBG_BCR_BVR_WCR_WVR_EL1(n) \
> /* DBGBVRn_EL1 */ \
> @@ -586,10 +638,10 @@ static const struct sys_reg_desc sys_reg_descs[] = {
> access_pmcr, reset_pmcr_el0, PMCR_EL0, },
> /* PMCNTENSET_EL0 */
> { Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b001),
> - trap_raz_wi },
> + access_pmcntenset, reset_unknown, PMCNTENSET_EL0 },
> /* PMCNTENCLR_EL0 */
> { Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b010),
> - trap_raz_wi },
> + access_pmcntenclr, reset_unknown, PMCNTENCLR_EL0 },
> /* PMOVSCLR_EL0 */
> { Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b011),
> trap_raz_wi },
> diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
> index 40ab4a0..2cfd9be 100644
> --- a/include/kvm/arm_pmu.h
> +++ b/include/kvm/arm_pmu.h
> @@ -49,6 +49,8 @@ void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, unsigned long select_idx,
> unsigned long val);
> unsigned long kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
> unsigned long select_idx);
> +void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, unsigned long val);
> +void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, unsigned long val);
> void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
> unsigned long select_idx);
> void kvm_pmu_init(struct kvm_vcpu *vcpu);
> @@ -61,6 +63,8 @@ unsigned long kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
> {
> return 0;
> }
> +void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, unsigned long val) {}
> +void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, unsigned long val) {}
> void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
> unsigned long select_idx) {}
> static inline void kvm_pmu_init(struct kvm_vcpu *vcpu) {}
> diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
> index 361fa51..cf59998 100644
> --- a/virt/kvm/arm/pmu.c
> +++ b/virt/kvm/arm/pmu.c
> @@ -134,6 +134,47 @@ unsigned long kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
> }
>
> /**
> + * kvm_pmu_enable_counter - enable selected PMU counter
> + * @vcpu: The vcpu pointer
> + * @val: the value guest writes to PMCNTENSET_EL0 register
> + *
> + * Call perf_event_enable to start counting the perf event
> + */
> +void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, unsigned long val)
> +{
> + int select_idx = find_first_bit(&val, 32);
Both of these functions should be able to handle more than one bit set
in val though, right?
Or perhaps you should make the parameter be select_idx and loop over the
bits in the caller, your choice.
> + struct kvm_pmu *pmu = &vcpu->arch.pmu;
> + struct kvm_pmc *pmc = &pmu->pmc[select_idx];
> +
> + if (pmc->perf_event) {
> + local64_set(&pmc->perf_event->count, 0);
why local64_set? Is this local to this CPU somehow?
why do we clear the count? Is it architecturally mandated?
> + perf_event_enable(pmc->perf_event);
> + if (pmc->perf_event->state != PERF_EVENT_STATE_ACTIVE)
> + printk("kvm: fail to enable event\n");
do you really want this print here? What could cause this error,
anything the VM can provoke?
> + }
what's the difference between having pmc->perf_event == NULL and having
pmc->perf_event->state == PERF_EVENT_STATE_INACTIVE ?
> + pmc->enable = true;
> +}
> +
> +/**
> + * kvm_pmu_disable_counter - disable selected PMU counter
> + * @vcpu: The vcpu pointer
> + * @val: the value guest writes to PMCNTENCLR_EL0 register
> + *
> + * Call perf_event_disable to stop counting the perf event
> + */
> +void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, unsigned long val)
> +{
> + int select_idx = find_first_bit(&val, 32);
ditto, see above.
> + struct kvm_pmu *pmu = &vcpu->arch.pmu;
> + struct kvm_pmc *pmc = &pmu->pmc[select_idx];
> +
> + if (pmc->perf_event)
> + perf_event_disable(pmc->perf_event);
> +
> + pmc->enable = false;
> +}
> +
> +/**
> * kvm_pmu_find_hw_event - find hardware event
> * @pmu: The pmu pointer
> * @event_select: The number of selected event type
> --
> 2.1.0
>
Thanks,
-Christoffer
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