Commit 3d91befb authored by Andrew Murray's avatar Andrew Murray Committed by Marc Zyngier
Browse files

arm64: KVM: Enable !VHE support for :G/:H perf event modifiers 



Enable/disable event counters as appropriate when entering and exiting
the guest to enable support for guest or host only event counting.

For both VHE and non-VHE we switch the counters between host/guest at
EL2.

The PMU may be on when we change which counters are enabled however
we avoid adding an isb as we instead rely on existing context
synchronisation events: the eret to enter the guest (__guest_enter)
and eret in kvm_call_hyp for __kvm_vcpu_run_nvhe on returning.

Signed-off-by: default avatarAndrew Murray <andrew.murray@arm.com>
Reviewed-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent d1947bc4

arch/arm64/include/asm/kvm_host.h

+3 −0
Original line number Diff line number Diff line
@@ -591,6 +591,9 @@ static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu) 


void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr);

void kvm_clr_pmu_events(u32 clr);



void __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt);

bool __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt);

#else

static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}

static inline void kvm_clr_pmu_events(u32 clr) {}

arch/arm64/kvm/hyp/switch.c

+6 −0
Original line number Diff line number Diff line
@@ -566,6 +566,7 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu) 
{

	struct kvm_cpu_context *host_ctxt;

	struct kvm_cpu_context *guest_ctxt;

	bool pmu_switch_needed;

	u64 exit_code;



	/*
@@ -585,6 +586,8 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu) 
	host_ctxt->__hyp_running_vcpu = vcpu;

	guest_ctxt = &vcpu->arch.ctxt;



	pmu_switch_needed = __pmu_switch_to_guest(host_ctxt);



	__sysreg_save_state_nvhe(host_ctxt);



	__activate_vm(kern_hyp_va(vcpu->kvm));
@@ -631,6 +634,9 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu) 
	 */

	__debug_switch_to_host(vcpu);



	if (pmu_switch_needed)

		__pmu_switch_to_host(host_ctxt);



	/* Returning to host will clear PSR.I, remask PMR if needed */

	if (system_uses_irq_prio_masking())

		gic_write_pmr(GIC_PRIO_IRQOFF);

arch/arm64/kvm/pmu.c

+39 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
 */

#include <linux/kvm_host.h>

#include <linux/perf_event.h>

#include <asm/kvm_hyp.h>



/*

 * Given the exclude_{host,guest} attributes, determine if we are going
@@ -43,3 +44,41 @@ void kvm_clr_pmu_events(u32 clr) 
	ctx->pmu_events.events_host &= ~clr;

	ctx->pmu_events.events_guest &= ~clr;

}



/**

 * Disable host events, enable guest events

 */

bool __hyp_text __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)

{

	struct kvm_host_data *host;

	struct kvm_pmu_events *pmu;



	host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);

	pmu = &host->pmu_events;



	if (pmu->events_host)

		write_sysreg(pmu->events_host, pmcntenclr_el0);



	if (pmu->events_guest)

		write_sysreg(pmu->events_guest, pmcntenset_el0);



	return (pmu->events_host || pmu->events_guest);

}



/**

 * Disable guest events, enable host events

 */

void __hyp_text __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)

{

	struct kvm_host_data *host;

	struct kvm_pmu_events *pmu;



	host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);

	pmu = &host->pmu_events;



	if (pmu->events_guest)

		write_sysreg(pmu->events_guest, pmcntenclr_el0);



	if (pmu->events_host)

		write_sysreg(pmu->events_host, pmcntenset_el0);

}

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