On 12/12/2018 10:29, Andrew Murray wrote:
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 :G events
as per the events exclude_host attribute.
With both VHE and non-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. However when using :H unless exclude_hv is set
on non-VHE then there is a small blackout window at the guest
entry/exit where host events are not captured.
Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx>
---
arch/arm64/kernel/perf_event.c | 51 ++++++++++++++++++++++++++++++++++++------
1 file changed, 44 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index de564ae..4a3c73d 100644
--- 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>
@@ -647,11 +648,26 @@ 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;
+ int flags = 0;
+ 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));
+
+ if (!attr->exclude_host)
+ flags |= KVM_PMU_EVENTS_HOST;
+ if (!attr->exclude_guest)
+ flags |= KVM_PMU_EVENTS_GUEST;
+
+ kvm_set_pmu_events(counter_bits, flags);
+
+ if (!attr->exclude_host) {
+ armv8pmu_enable_counter(idx);
+ if (armv8pmu_event_is_chained(event))
+ armv8pmu_enable_counter(idx - 1);
+ }
}
static inline int armv8pmu_disable_counter(int idx)
@@ -664,11 +680,20 @@ 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);
+
+ if (!attr->exclude_host) {
+ if (armv8pmu_event_is_chained(event))
+ armv8pmu_disable_counter(idx - 1);
+ armv8pmu_disable_counter(idx);
+ }
It may be helpful to add in a comment why we do this only for !exclude_host.
Either way,
Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
