arm64: arm_pmu: Add !VHE support for exclude_host/exclude_guest attributes

Add support for the :G and :H attributes in perf by handling the
exclude_host/exclude_guest event attributes.

We notify KVM of counters that we wish to be enabled or disabled on
guest entry/exit and thus defer from starting or stopping events based
on their event attributes.

With !VHE we switch the counters between host/guest at EL2. We are able
to eliminate counters counting host events on the boundaries of guest
entry/exit when using :G by filtering out EL2 for exclude_host. When
using !exclude_hv there is a small blackout window at the guest
entry/exit where host events are not captured.

Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index cccf4fc..6bb28aa 100644 (file)
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -26,6 +26,7 @@
 
 #include <linux/acpi.h>
 #include <linux/clocksource.h>
+#include <linux/kvm_host.h>
 #include <linux/of.h>
 #include <linux/perf/arm_pmu.h>
 #include <linux/platform_device.h>
@@ -528,11 +529,21 @@ static inline int armv8pmu_enable_counter(int idx)
 
 static inline void armv8pmu_enable_event_counter(struct perf_event *event)
 {
+       struct perf_event_attr *attr = &event->attr;
        int idx = event->hw.idx;
+       u32 counter_bits = BIT(ARMV8_IDX_TO_COUNTER(idx));
 
-       armv8pmu_enable_counter(idx);
        if (armv8pmu_event_is_chained(event))
-               armv8pmu_enable_counter(idx - 1);
+               counter_bits |= BIT(ARMV8_IDX_TO_COUNTER(idx - 1));
+
+       kvm_set_pmu_events(counter_bits, attr);
+
+       /* We rely on the hypervisor switch code to enable guest counters */
+       if (!kvm_pmu_counter_deferred(attr)) {
+               armv8pmu_enable_counter(idx);
+               if (armv8pmu_event_is_chained(event))
+                       armv8pmu_enable_counter(idx - 1);
+       }
 }
 
 static inline int armv8pmu_disable_counter(int idx)
@@ -545,11 +556,21 @@ static inline int armv8pmu_disable_counter(int idx)
 static inline void armv8pmu_disable_event_counter(struct perf_event *event)
 {
        struct hw_perf_event *hwc = &event->hw;
+       struct perf_event_attr *attr = &event->attr;
        int idx = hwc->idx;
+       u32 counter_bits = BIT(ARMV8_IDX_TO_COUNTER(idx));
 
        if (armv8pmu_event_is_chained(event))
-               armv8pmu_disable_counter(idx - 1);
-       armv8pmu_disable_counter(idx);
+               counter_bits |= BIT(ARMV8_IDX_TO_COUNTER(idx - 1));
+
+       kvm_clr_pmu_events(counter_bits);
+
+       /* We rely on the hypervisor switch code to disable guest counters */
+       if (!kvm_pmu_counter_deferred(attr)) {
+               if (armv8pmu_event_is_chained(event))
+                       armv8pmu_disable_counter(idx - 1);
+               armv8pmu_disable_counter(idx);
+       }
 }
 
 static inline int armv8pmu_enable_intens(int idx)
@@ -829,11 +850,16 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
                if (!attr->exclude_kernel)
                        config_base |= ARMV8_PMU_INCLUDE_EL2;
        } else {
-               if (attr->exclude_kernel)
-                       config_base |= ARMV8_PMU_EXCLUDE_EL1;
-               if (!attr->exclude_hv)
+               if (!attr->exclude_hv && !attr->exclude_host)
                        config_base |= ARMV8_PMU_INCLUDE_EL2;
        }
+
+       /*
+        * Filter out !VHE kernels and guest kernels
+        */
+       if (attr->exclude_kernel)
+               config_base |= ARMV8_PMU_EXCLUDE_EL1;
+
        if (attr->exclude_user)
                config_base |= ARMV8_PMU_EXCLUDE_EL0;
 
@@ -863,6 +889,9 @@ static void armv8pmu_reset(void *info)
                armv8pmu_disable_intens(idx);
        }
 
+       /* Clear the counters we flip at guest entry/exit */
+       kvm_clr_pmu_events(U32_MAX);
+
        /*
         * Initialize & Reset PMNC. Request overflow interrupt for
         * 64 bit cycle counter but cheat in armv8pmu_write_counter().