An ugly interaction between the use of PMSELR_EL0 in a host kernel and
the use of PMXEVCNTR_EL0 in a guest has recently come to light [1],
leading to the guest taking an UNDEF exception in EL1 when using the
PMU.
The fix is pretty simple ("don't do that!"), making the PMU useable on
X-Gene, which seems to have a stricter (but nonetheless valid)
interpretation of the architecture.
Patches against 4.9-rc6.
[1] https://lists.cs.columbia.edu/pipermail/kvmarm/2016-November/022545.html
Marc Zyngier (2):
arm64: PMU: Do not use PMSELR_EL0 to access PMCCFILTR_EL0
arm64: PMU: Reset PMSELR_EL0 to a sane value at boot time
arch/arm64/kernel/perf_event.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--
2.1.4
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