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>

1 files changed, 39 insertions, 0 deletions

diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 5414b134f99a..599e6d3f692e 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 +44,41 @@ 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);
+}