Re: [PATCH v8 13/20] KVM: ARM64: Add access handler for PMSWINC register

[Marc Zyngier <marc.zyngier@arm.com>]

On 22/12/15 08:08, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@linaro.org>
> 
> Add access handler which emulates writing and reading PMSWINC
> register and add support for creating software increment event.
> 
> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
> ---
>  arch/arm64/kvm/sys_regs.c | 18 +++++++++++++++++-
>  include/kvm/arm_pmu.h     |  2 ++
>  virt/kvm/arm/pmu.c        | 33 +++++++++++++++++++++++++++++++++
>  3 files changed, 52 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index d61f271dd..92021dc 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -682,6 +682,21 @@ static bool access_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
>  	return true;
>  }
>  
> +static bool access_pmswinc(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> +			   const struct sys_reg_desc *r)
> +{
> +	u64 mask;
> +
> +	if (p->is_write) {
> +		mask = kvm_pmu_valid_counter_mask(vcpu);
> +		kvm_pmu_software_increment(vcpu, p->regval & mask);
> +	} else {
> +		kvm_inject_undefined(vcpu);

"return false;" instead.

> +	}
> +
> +	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 */						\
> @@ -892,7 +907,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	  access_pmovs, NULL, PMOVSSET_EL0 },
>  	/* PMSWINC_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b100),
> -	  trap_raz_wi },
> +	  access_pmswinc, reset_unknown, PMSWINC_EL0 },
>  	/* PMSELR_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b101),
>  	  access_pmselr, reset_unknown, PMSELR_EL0 },
> @@ -1231,6 +1246,7 @@ static const struct sys_reg_desc cp15_regs[] = {
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 1), access_pmcnten },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 2), access_pmcnten },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 3), access_pmovs },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 4), access_pmswinc },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 5), access_pmselr },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 6), access_pmceid },
>  	{ Op1( 0), CRn( 9), CRm(12), Op2( 7), access_pmceid },
> diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
> index 244970b..67d168c 100644
> --- a/include/kvm/arm_pmu.h
> +++ b/include/kvm/arm_pmu.h
> @@ -40,6 +40,7 @@ u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu);
>  void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, u64 val);
>  void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, u64 val);
>  void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val);
> +void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val);
>  void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
>  				    u64 select_idx);
>  #else
> @@ -57,6 +58,7 @@ u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu)
>  void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, u64 val) {}
>  void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, u64 val) {}
>  void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val) {}
> +void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val) {}
>  void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
>  				    u64 select_idx) {}
>  #endif
> diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
> index c23d57e..409f3c4 100644
> --- a/virt/kvm/arm/pmu.c
> +++ b/virt/kvm/arm/pmu.c
> @@ -160,6 +160,35 @@ void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val)
>  		kvm_vcpu_kick(vcpu);
>  }
>  
> +/**
> + * kvm_pmu_software_increment - do software increment
> + * @vcpu: The vcpu pointer
> + * @val: the value guest writes to PMSWINC register
> + */
> +void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val)
> +{
> +	int i;
> +	u64 type, enable, reg;
> +
> +	if (val == 0)
> +		return;
> +
> +	for (i = 0; i < ARMV8_CYCLE_IDX; i++) {
> +		if (!(val & BIT(i)))
> +			continue;
> +		type = vcpu_sys_reg(vcpu, PMEVTYPER0_EL0 + i)
> +		       & ARMV8_EVTYPE_EVENT;
> +		enable = vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
> +		if ((type == 0) && (enable & BIT(i))) {

nit: Should we have a ARMV8_EVTYPE_EVENT_SW_INCR instead of just
checking for zero?

> +			reg = vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) + 1;
> +			reg = lower_32_bits(reg);
> +			vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;
> +			if (!reg)
> +				kvm_pmu_overflow_set(vcpu, BIT(i));
> +		}
> +	}
> +}
> +
>  static inline bool kvm_pmu_counter_is_enabled(struct kvm_vcpu *vcpu,
>  					      u64 select_idx)
>  {
> @@ -189,6 +218,10 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
>  	kvm_pmu_stop_counter(vcpu, pmc);
>  	eventsel = data & ARMV8_EVTYPE_EVENT;
>  
> +	/* For software increment event it does't need to create perf event */

nit: ... "Software events do not need to be backed by a perf event"

> +	if (eventsel == 0)
> +		return;
> +
>  	memset(&attr, 0, sizeof(struct perf_event_attr));
>  	attr.type = PERF_TYPE_RAW;
>  	attr.size = sizeof(attr);
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...