Subject: [PATCH v14 15/20] KVM: ARM64: Add PMU overflow interrupt routing

From: [email-masked] (Christoffer Dall)
Date: Fri, 26 Feb 2016 09:52:19 +0100

On Wed, Feb 24, 2016 at 10:33:37PM +0800, Shannon Zhao wrote:
> When calling perf_event_create_kernel_counter to create perf_event,
> assign a overflow handler. Then when the perf event overflows, set the
> corresponding bit of guest PMOVSSET register. If this counter is enabled
> and its interrupt is enabled as well, kick the vcpu to sync the
> interrupt.
> 
> On VM entry, if there is counter overflowed and interrupt level is
> changed, inject the interrupt with corresponding level. On VM exit, sync
> the interrupt level as well if it has been changed.
> 
> Signed-off-by: Shannon Zhao <[email-masked]>
> Reviewed-by: Marc Zyngier <[email-masked]>
> Reviewed-by: Andrew Jones <[email-masked]>
> ---
>  arch/arm/kvm/arm.c    |  5 ++++
>  include/kvm/arm_pmu.h |  5 ++++
>  virt/kvm/arm/pmu.c    | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++-
>  3 files changed, 78 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index dda1959..5c133ac 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -28,6 +28,7 @@
>  #include <linux/sched.h>
>  #include <linux/kvm.h>
>  #include <trace/events/kvm.h>
> +#include <kvm/arm_pmu.h>
>  
>  #define CREATE_TRACE_POINTS
>  #include "trace.h"
> @@ -577,6 +578,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  		 * non-preemptible context.
>  		 */
>  		preempt_disable();
> +		kvm_pmu_flush_hwstate(vcpu);
>  		kvm_timer_flush_hwstate(vcpu);
>  		kvm_vgic_flush_hwstate(vcpu);
>  
> @@ -593,6 +595,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  		if (ret <= 0 || need_new_vmid_gen(vcpu->kvm) ||
>  			vcpu->arch.power_off || vcpu->arch.pause) {
>  			local_irq_enable();
> +			kvm_pmu_sync_hwstate(vcpu);
>  			kvm_timer_sync_hwstate(vcpu);
>  			kvm_vgic_sync_hwstate(vcpu);
>  			preempt_enable();
> @@ -641,6 +644,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  		kvm_guest_exit();
>  		trace_kvm_exit(ret, kvm_vcpu_trap_get_class(vcpu), *vcpu_pc(vcpu));
>  
> +		kvm_pmu_sync_hwstate(vcpu);
> +

nit: I think you should move this below the comment and update the
comment say "We must sync the timer and PMU state before ..."

>  		/*
>  		 * We must sync the timer state before the vgic state so that
>  		 * the vgic can properly sample the updated state of the
> diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
> index 8bc92d1..9c184ed 100644
> --- a/include/kvm/arm_pmu.h
> +++ b/include/kvm/arm_pmu.h
> @@ -35,6 +35,7 @@ struct kvm_pmu {
>  	int irq_num;
>  	struct kvm_pmc pmc[ARMV8_PMU_MAX_COUNTERS];
>  	bool ready;
> +	bool irq_level;
>  };
>  
>  #define kvm_arm_pmu_v3_ready(v)		((v)->arch.pmu.ready)
> @@ -44,6 +45,8 @@ 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_flush_hwstate(struct kvm_vcpu *vcpu);
> +void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu);
>  void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val);
>  void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val);
>  void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
> @@ -67,6 +70,8 @@ static inline u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu)
>  static inline void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, u64 val) {}
>  static inline void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, u64 val) {}
>  static inline void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val) {}
> +static inline void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu) {}
> +static inline void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val) {}
>  static inline void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val) {}
>  static inline void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu,
> diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
> index cda869c..74e858c 100644
> --- a/virt/kvm/arm/pmu.c
> +++ b/virt/kvm/arm/pmu.c
> @@ -21,6 +21,7 @@
>  #include <linux/perf_event.h>
>  #include <asm/kvm_emulate.h>
>  #include <kvm/arm_pmu.h>
> +#include <kvm/arm_vgic.h>
>  
>  /**
>   * kvm_pmu_get_counter_value - get PMU counter value
> @@ -180,6 +181,71 @@ void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val)
>  		kvm_vcpu_kick(vcpu);
>  }
>  
> +static void kvm_pmu_update_state(struct kvm_vcpu *vcpu)
> +{
> +	struct kvm_pmu *pmu = &vcpu->arch.pmu;
> +	bool overflow;
> +
> +	if (!kvm_arm_pmu_v3_ready(vcpu))
> +		return;
> +
> +	overflow = !!kvm_pmu_overflow_status(vcpu);
> +	if (pmu->irq_level != overflow) {
> +		pmu->irq_level = overflow;
> +		kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
> +				    pmu->irq_num, overflow);
> +	}
> +}
> +
> +/**
> + * kvm_pmu_flush_hwstate - flush pmu state to cpu
> + * @vcpu: The vcpu pointer
> + *
> + * Check if the PMU has overflowed while we were running in the host, and inject
> + * an interrupt if that was the case.
> + */
> +void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu)
> +{
> +	kvm_pmu_update_state(vcpu);
> +}
> +
> +/**
> + * kvm_pmu_sync_hwstate - sync pmu state from cpu
> + * @vcpu: The vcpu pointer
> + *
> + * Check if the PMU has overflowed while we were running in the guest, and
> + * inject an interrupt if that was the case.
> + */
> +void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu)
> +{
> +	kvm_pmu_update_state(vcpu);
> +}
> +
> +static inline struct kvm_vcpu *kvm_pmc_to_vcpu(struct kvm_pmc *pmc)
> +{
> +	struct kvm_pmu *pmu;
> +	struct kvm_vcpu_arch *vcpu_arch;
> +
> +	pmc -= pmc->idx;
> +	pmu = container_of(pmc, struct kvm_pmu, pmc[0]);
> +	vcpu_arch = container_of(pmu, struct kvm_vcpu_arch, pmu);
> +	return container_of(vcpu_arch, struct kvm_vcpu, arch);
> +}
> +
> +/**
> + * When perf event overflows, call kvm_pmu_overflow_set to set overflow status.
> + */
> +static void kvm_pmu_perf_overflow(struct perf_event *perf_event,
> +				  struct perf_sample_data *data,
> +				  struct pt_regs *regs)
> +{
> +	struct kvm_pmc *pmc = perf_event->overflow_handler_context;
> +	struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc);
> +	int idx = pmc->idx;
> +
> +	kvm_pmu_overflow_set(vcpu, BIT(idx));
> +}
> +
>  /**
>   * kvm_pmu_software_increment - do software increment
>   * @vcpu: The vcpu pointer
> @@ -291,7 +357,8 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
>  	/* The initial sample period (overflow count) of an event. */
>  	attr.sample_period = (-counter) & pmc->bitmask;
>  
> -	event = perf_event_create_kernel_counter(&attr, -1, current, NULL, pmc);
> +	event = perf_event_create_kernel_counter(&attr, -1, current,
> +						 kvm_pmu_perf_overflow, pmc);
>  	if (IS_ERR(event)) {
>  		pr_err_once("kvm: pmu event creation failed %ld\n",
>  			    PTR_ERR(event));
> -- 
> 2.1.0
> 

Reviewed-by: Christoffer Dall <[email-masked]>