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arm64: KVM: Add accessors to track guest/host only counters 

In order to effeciently switch events_{guest,host} perf counters at
guest entry/exit we add bitfields to kvm_cpu_context for guest and host
events as well as accessors for updating them.

A function is also provided which allows the PMU driver to determine
if a counter should start counting when it is enabled. With exclude_host,
we may only start counting when entering the guest.

Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Andrew Murray 2019-04-09 20:22:12 +01:00 committed by Marc Zyngier
parent 630a16854d
commit eb41238cf1
3 changed files with 63 additions and 1 deletions
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17
arch/arm64/include/asm/kvm_host.h
View File

@ -233,8 +233,14 @@ struct kvm_cpu_context {
struct kvm_vcpu *__hyp_running_vcpu;
};
struct kvm_pmu_events {
u32 events_host;
u32 events_guest;
};
struct kvm_host_data {
struct kvm_cpu_context host_ctxt;
struct kvm_pmu_events pmu_events;
};
typedef struct kvm_host_data kvm_host_data_t;
@ -572,11 +578,22 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu);
static inline bool kvm_pmu_counter_deferred(struct perf_event_attr *attr)
{
return attr->exclude_host;
}
#ifdef CONFIG_KVM /* Avoid conflicts with core headers if CONFIG_KVM=n */
static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
{
return kvm_arch_vcpu_run_map_fp(vcpu);
}
void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr);
void kvm_clr_pmu_events(u32 clr);
#else
static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}
static inline void kvm_clr_pmu_events(u32 clr) {}
#endif
static inline void kvm_arm_vhe_guest_enter(void)

2
arch/arm64/kvm/Makefile
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@ -17,7 +17,7 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/psci.o $(KVM)/arm/perf.o
kvm-$(CONFIG_KVM_ARM_HOST) += inject_fault.o regmap.o va_layout.o
kvm-$(CONFIG_KVM_ARM_HOST) += hyp.o hyp-init.o handle_exit.o
kvm-$(CONFIG_KVM_ARM_HOST) += guest.o debug.o reset.o sys_regs.o sys_regs_generic_v8.o
kvm-$(CONFIG_KVM_ARM_HOST) += vgic-sys-reg-v3.o fpsimd.o
kvm-$(CONFIG_KVM_ARM_HOST) += vgic-sys-reg-v3.o fpsimd.o pmu.o
kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/aarch32.o
kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic.o

45
arch/arm64/kvm/pmu.c Normal file
View File

@ -0,0 +1,45 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2019 Arm Limited
* Author: Andrew Murray <Andrew.Murray@arm.com>
*/
#include <linux/kvm_host.h>
#include <linux/perf_event.h>
/*
* Given the exclude_{host,guest} attributes, determine if we are going
* to need to switch counters at guest entry/exit.
*/
static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
{
/* Only switch if attributes are different */
return (attr->exclude_host != attr->exclude_guest);
}
/*
* Add events to track that we may want to switch at guest entry/exit
* time.
*/
void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
{
struct kvm_host_data *ctx = this_cpu_ptr(&kvm_host_data);
if (!kvm_pmu_switch_needed(attr))
return;
if (!attr->exclude_host)
ctx->pmu_events.events_host |= set;
if (!attr->exclude_guest)
ctx->pmu_events.events_guest |= set;
}
/*
* Stop tracking events
*/
void kvm_clr_pmu_events(u32 clr)
{
struct kvm_host_data *ctx = this_cpu_ptr(&kvm_host_data);
ctx->pmu_events.events_host &= ~clr;
ctx->pmu_events.events_guest &= ~clr;
}