Commit 30cd8604 authored by Eric Hankland's avatar Eric Hankland Committed by Paolo Bonzini
Browse files

KVM: x86: Add fixed counters to PMU filter 



Updates KVM_CAP_PMU_EVENT_FILTER so it can also whitelist or blacklist
fixed counters.

Signed-off-by: default avatarEric Hankland <ehankland@google.com>
[No need to check padding fields for zero. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 88dddc11

Documentation/virtual/kvm/api.txt

+10 −5
Original line number Diff line number Diff line
@@ -4092,6 +4092,9 @@ Returns: 0 on success, -1 on error 
struct kvm_pmu_event_filter {

	__u32 action;

	__u32 nevents;

	__u32 fixed_counter_bitmap;

	__u32 flags;

	__u32 pad[4];

	__u64 events[0];

};
@@ -4099,8 +4102,10 @@ This ioctl restricts the set of PMU events that the guest can program. 
The argument holds a list of events which will be allowed or denied.

The eventsel+umask of each event the guest attempts to program is compared

against the events field to determine whether the guest should have access.

This only affects general purpose counters; fixed purpose counters can

be disabled by changing the perfmon CPUID leaf.

The events field only controls general purpose counters; fixed purpose

counters are controlled by the fixed_counter_bitmap.



No flags are defined yet, the field must be zero.



Valid values for 'action':

#define KVM_PMU_EVENT_ALLOW 0

arch/x86/include/uapi/asm/kvm.h

+6 −3
Original line number Diff line number Diff line
@@ -437,6 +437,9 @@ struct kvm_nested_state { 
struct kvm_pmu_event_filter {

	__u32 action;

	__u32 nevents;

	__u32 fixed_counter_bitmap;

	__u32 flags;

	__u32 pad[4];

	__u64 events[0];

};

arch/x86/kvm/pmu.c

+19 −4
Original line number Diff line number Diff line
@@ -19,8 +19,8 @@ 
#include "lapic.h"

#include "pmu.h"



/* This keeps the total size of the filter under 4k. */

#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 63

/* This is enough to filter the vast majority of currently defined events. */

#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 300



/* NOTE:

 * - Each perf counter is defined as "struct kvm_pmc";
@@ -206,12 +206,24 @@ void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int idx) 
{

	unsigned en_field = ctrl & 0x3;

	bool pmi = ctrl & 0x8;

	struct kvm_pmu_event_filter *filter;

	struct kvm *kvm = pmc->vcpu->kvm;



	pmc_stop_counter(pmc);



	if (!en_field || !pmc_is_enabled(pmc))

		return;



	filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);

	if (filter) {

		if (filter->action == KVM_PMU_EVENT_DENY &&

		    test_bit(idx, (ulong *)&filter->fixed_counter_bitmap))

			return;

		if (filter->action == KVM_PMU_EVENT_ALLOW &&

		    !test_bit(idx, (ulong *)&filter->fixed_counter_bitmap))

			return;

	}



	pmc_reprogram_counter(pmc, PERF_TYPE_HARDWARE,

			      kvm_x86_ops->pmu_ops->find_fixed_event(idx),

			      !(en_field & 0x2), /* exclude user */
@@ -385,6 +397,9 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp) 
	    tmp.action != KVM_PMU_EVENT_DENY)

		return -EINVAL;



	if (tmp.flags != 0)

		return -EINVAL;



	if (tmp.nevents > KVM_PMU_EVENT_FILTER_MAX_EVENTS)

		return -E2BIG;

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