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

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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: Andrew Murray <andrew.murray@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Andrew Murray 2019-04-09 20:22:14 +01:00 committed by Marc Zyngier
parent d1947bc4bc
commit 3d91befbb3
3 changed files with 48 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
arch/arm64/include/asm/kvm_host.h
View file

@ -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) {}

6
arch/arm64/kvm/hyp/switch.c
View file

@ -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);

39
arch/arm64/kvm/pmu.c
View file

@ -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);
}