KVM: x86/pmu: Remove impossible events from the pmu event filter

If it's not possible for an event in the pmu event filter to match a
pmu event being programmed by the guest, it's pointless to have it in
the list.  Opt for a shorter list by removing those events.

Because this is established uAPI the pmu event filter can't outright
rejected these events as garbage and return an error.  Instead, play
nice and remove them from the list.

Also, opportunistically rewrite the comment when the filter is set to
clarify that it guards against *all* TOCTOU attacks on the verified
data.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Link: https://lore.kernel.org/r/20221220161236.555143-3-aaronlewis@google.com


Signed-off-by: Sean Christopherson <seanjc@google.com>