Re: [PATCH v4 3/7] kvm: x86/pmu: prepare the pmu event filter for masked events

[Jim Mattson <jmattson@google.com>]

On Wed, Aug 31, 2022 at 9:21 AM Aaron Lewis <aaronlewis@google.com> wrote:
>
> Create an internal representation for filter events to abstract the
> events userspace uses from the events the kernel uses.  That will allow
> the kernel to use a common event and a common code path between the
> different types of filter events used in userspace once masked events
> are introduced.
>
> No functional changes intended
>
> Signed-off-by: Aaron Lewis <aaronlewis@google.com>
> ---
>  arch/x86/kvm/pmu.c | 118 ++++++++++++++++++++++++++++++++-------------
>  arch/x86/kvm/pmu.h |  16 ++++++
>  2 files changed, 100 insertions(+), 34 deletions(-)
>
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index e7d94e6b7f28..50a36cc5bfd0 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -239,6 +239,19 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc)
>         return true;
>  }
>
> +static inline u16 get_event_select(u64 eventsel)
> +{
> +       u64 e = eventsel &
> +               static_call(kvm_x86_pmu_get_eventsel_event_mask)();
> +
> +       return (e & ARCH_PERFMON_EVENTSEL_EVENT) | ((e >> 24) & 0xF00ULL);
> +}
> +
> +static inline u8 get_unit_mask(u64 eventsel)
> +{
> +       return (eventsel & ARCH_PERFMON_EVENTSEL_UMASK) >> 8;
> +}
> +
>  static int cmp_u64(const void *pa, const void *pb)
>  {
>         u64 a = *(u64 *)pa;
> @@ -247,53 +260,63 @@ static int cmp_u64(const void *pa, const void *pb)
>         return (a > b) - (a < b);
>  }
>
> -static inline u64 get_event_select(u64 eventsel)
> +static u64 *find_filter_entry(struct kvm_pmu_event_filter *filter, u64 key)
> +{
> +       return bsearch(&key, filter->events, filter->nevents,
> +                         sizeof(filter->events[0]), cmp_u64);
> +}
> +
> +static bool filter_contains_match(struct kvm_pmu_event_filter *filter,
> +                                 u64 eventsel)
> +{
> +       u16 event_select = get_event_select(eventsel);
> +       u8 unit_mask = get_unit_mask(eventsel);
> +       u64 key;
> +
> +       key = KVM_PMU_ENCODE_FILTER_ENTRY(event_select, unit_mask);
> +       if (find_filter_entry(filter, key))
> +               return true;
> +       return false;

Perhaps just:
        return find_filter_entry(filter, key);

Reviewed-by: Jim Mattson <jmattson@google.com>