diff mbox series

[v4,2/7] kvm: x86/pmu: Remove invalid raw events from the pmu event filter

Message ID 20220831162124.947028-3-aaronlewis@google.com (mailing list archive)
State New, archived
Headers show
Series Introduce and test masked events | expand

Commit Message

Aaron Lewis Aug. 31, 2022, 4:21 p.m. UTC 
If a raw event is invalid, i.e. bits set outside the event select +
unit mask, the event will never match the search, so it's pointless
to have it in the list.  Opt for a shorter list by removing invalid
raw events.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
---
 arch/x86/kvm/pmu.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

Comments

Jim Mattson Sept. 14, 2022, 6:17 p.m. UTC | #1 
On Wed, Aug 31, 2022 at 9:21 AM Aaron Lewis <aaronlewis@google.com> wrote:
>
> If a raw event is invalid, i.e. bits set outside the event select +
> unit mask, the event will never match the search, so it's pointless
> to have it in the list.  Opt for a shorter list by removing invalid
> raw events.
>
> Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
diff mbox series

Patch

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 98f383789579..e7d94e6b7f28 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -577,6 +577,38 @@  void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu, u64 perf_hw_id)
 }
 EXPORT_SYMBOL_GPL(kvm_pmu_trigger_event);
 
+static inline u64 get_event_filter_mask(void)
+{
+	u64 event_select_mask =
+		static_call(kvm_x86_pmu_get_eventsel_event_mask)();
+
+	return event_select_mask | ARCH_PERFMON_EVENTSEL_UMASK;
+}
+
+static inline bool is_event_valid(u64 event, u64 mask)
+{
+	return !(event & ~mask);
+}
+
+static void remove_invalid_raw_events(struct kvm_pmu_event_filter *filter)
+{
+	u64 raw_mask;
+	int i, j;
+
+	if (filter->flags)
+		return;
+
+	raw_mask = get_event_filter_mask();
+	for (i = 0, j = 0; i < filter->nevents; i++) {
+		u64 raw_event = filter->events[i];
+
+		if (is_event_valid(raw_event, raw_mask))
+			filter->events[j++] = raw_event;
+	}
+
+	filter->nevents = j;
+}
+
 int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
 {
 	struct kvm_pmu_event_filter tmp, *filter;
@@ -608,6 +640,8 @@  int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
 	/* Ensure nevents can't be changed between the user copies. */
 	*filter = tmp;
 
+	remove_invalid_raw_events(filter);
+
 	/*
 	 * Sort the in-kernel list so that we can search it with bsearch.
 	 */