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KVM: x86/pmu: Remove impossible events from the pmu event filter
authorAaron Lewis <aaronlewis@google.com>
Tue, 20 Dec 2022 16:12:31 +0000 (16:12 +0000)
committerSean Christopherson <seanjc@google.com>
Tue, 24 Jan 2023 18:06:11 +0000 (10:06 -0800)
commit8589827fd5342b0ae3703e3093a946d708c44f3a
tree7b9009a0f8921438ff2d4595acf282a218547cd3
parent6a5cba7bed35580effda9fb1872b274da47e6b23
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>
arch/x86/kvm/pmu.c