Patchwork [v13,5/8] arm64: KVM: Enable !VHE support for :G/:H perf event modifiers

login
register
mail settings
Submitter Andrew Murray
Date April 9, 2019, 7:22 p.m.
Message ID <20190409192217.23459-6-andrew.murray@arm.com>
Download mbox | patch
Permalink /patch/768943/
State New
Headers show

Comments

Andrew Murray - April 9, 2019, 7:22 p.m.
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>
---
 arch/arm64/include/asm/kvm_host.h |  3 +++
 arch/arm64/kvm/hyp/switch.c       |  6 +++++
 arch/arm64/kvm/pmu.c              | 40 +++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)
Suzuki K Poulose - April 15, 2019, 1:02 p.m.
On 09/04/2019 20:22, Andrew Murray wrote:
> 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>

Patch

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 213465196e6b..a3bfb75f0be9 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -539,6 +539,9 @@  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 3563fe655cd5..d1dc40e53f22 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -524,6 +524,7 @@  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;
 
 	/*
@@ -543,6 +544,8 @@  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));
@@ -589,6 +592,9 @@  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 5414b134f99a..48949f0cdba0 100644
--- 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 +44,42 @@  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);
+}
+