Commits
Marc Zyngier committed 959e95305f1
arm64: KVM: pmu: Reset PMSELR_EL0.SEL to a sane value before entering the guest commit 21cbe3cc8a48ff17059912e019fbde28ed54745a upstream. The ARMv8 architecture allows the cycle counter to be configured by setting PMSELR_EL0.SEL==0x1f and then accessing PMXEVTYPER_EL0, hence accessing PMCCFILTR_EL0. But it disallows the use of PMSELR_EL0.SEL==0x1f to access the cycle counter itself through PMXEVCNTR_EL0. Linux itself doesn't violate this rule, but we may end up with PMSELR_EL0.SEL being set to 0x1f when we enter a guest. If that guest accesses PMXEVCNTR_EL0, the access may UNDEF at EL1, despite the guest not having done anything wrong. In order to avoid this unfortunate course of events (haha!), let's sanitize PMSELR_EL0 on guest entry. This ensures that the guest won't explode unexpectedly. Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>