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. When using VHE, EL2 is unused by the guest - therefore we can filter out these events with the PMU as per the 'exclude_host' attribute. With both VHE and non-VHE we switch the counters between host/guest at EL2. With non-VHE when using 'exclude_host' we filter out EL2. These changes eliminate counters counting host events on the boundaries of guest entry/exit when using :G. 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 <[email protected]> --- arch/arm64/kernel/perf_event.c | 41 +++++++++++++++++++++++++++++++++++------ 1 file changed, 35 insertions(+), 6 deletions(-) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index de564ae..412bd80 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 +648,23 @@ 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)); + + if (attr->exclude_host) + kvm_set_clr_guest_pmu_events(0, counter_bits); + if (attr->exclude_guest) + kvm_set_clr_host_pmu_events(0, counter_bits); + + 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 +677,23 @@ 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)); + + if (attr->exclude_host) + kvm_set_clr_guest_pmu_events(counter_bits, 0); + if (attr->exclude_guest) + kvm_set_clr_host_pmu_events(counter_bits, 0); + + if (!attr->exclude_host) { + if (armv8pmu_event_is_chained(event)) + armv8pmu_disable_counter(idx - 1); + armv8pmu_disable_counter(idx); + } } static inline int armv8pmu_enable_intens(int idx) @@ -945,12 +970,12 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event, * with other architectures (x86 and Power). */ if (is_kernel_in_hyp_mode()) { - if (!attr->exclude_kernel) + if (!attr->exclude_kernel && !attr->exclude_host) 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; } if (attr->exclude_user) @@ -976,6 +1001,10 @@ static void armv8pmu_reset(void *info) armv8pmu_disable_intens(idx); } + /* Clear the counters we flip at guest entry/exit */ + kvm_set_clr_host_pmu_events(U32_MAX, 0); + kvm_set_clr_guest_pmu_events(U32_MAX, 0); + /* * Initialize & Reset PMNC. Request overflow interrupt for * 64 bit cycle counter but cheat in armv8pmu_write_counter(). -- 2.7.4 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
