Hi Andrew,
On 04/02/2019 16:53, Andrew Murray wrote:
The perf event sample_period is currently set based upon the current
counter value, when PMXEVTYPER is written to and the perf event is created.
However the user may choose to write the type before the counter value in
which case sample_period will be set incorrectly. Let's instead decouple
event creation from PMXEVTYPER and (re)create the event in either
suitation.
Signed-off-by: Andrew Murray <andrew.mur...@arm.com>
---
virt/kvm/arm/pmu.c | 40 +++++++++++++++++++++++++++++++---------
1 file changed, 31 insertions(+), 9 deletions(-)
diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 6e7c179..95d74ec 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -24,6 +24,7 @@
#include <kvm/arm_pmu.h>
#include <kvm/arm_vgic.h>
+static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx);
/**
* kvm_pmu_get_counter_value - get PMU counter value
* @vcpu: The vcpu pointer
@@ -62,6 +63,9 @@ void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64
select_idx, u64 val)
reg = (select_idx == ARMV8_PMU_CYCLE_IDX)
? PMCCNTR_EL0 : PMEVCNTR0_EL0 + select_idx;
__vcpu_sys_reg(vcpu, reg) += (s64)val - kvm_pmu_get_counter_value(vcpu,
select_idx);
+
+ /* Recreate the perf event to reflect the updated sample_period */
+ kvm_pmu_create_perf_event(vcpu, select_idx);
}
/**
@@ -378,23 +382,22 @@ static bool kvm_pmu_counter_is_enabled(struct kvm_vcpu
*vcpu, u64 select_idx)
}
/**
- * kvm_pmu_set_counter_event_type - set selected counter to monitor some event
+ * kvm_pmu_create_perf_event - create a perf event for a counter
* @vcpu: The vcpu pointer
- * @data: The data guest writes to PMXEVTYPER_EL0
+ * @data: Type of event as per PMXEVTYPER_EL0 format
* @select_idx: The number of selected counter
nit: data no longer exists.
- *
- * When OS accesses PMXEVTYPER_EL0, that means it wants to set a PMC to count
an
- * event with given hardware event number. Here we call perf_event API to
- * emulate this action and create a kernel perf event for it.
*/
-void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
- u64 select_idx)
+static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx)
{
With the comment from Julien addressed,
Reviewed-by: Suzuki K Poulose <suzuki.pou...@arm.com>
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