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: Andrew Murray <andrew.murray@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 655ad08..645d74c 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -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) {}

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 5444b9c..22b4c33 100644 (file)
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -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);

diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 5414b13..599e6d3 100644 (file)
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -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);
+}