I recently came across a number of PMU emulation bugs, all which can
result in unexpected behaviours in an unsuspecting guest. The first
two patches already have been discussed on the list, but I'm including
them here as part of a slightly longer series.
The third patch is new as of v2, and fixes a bug preventing chained
events from ever being used.
The fourth patch is also new as of v2, and is an arm64 PMU change for
which I clearly don't know what I'm doing. I'd appreciate some
guidance from Will or Mark.
The last patch fixes an issue that has been here from day one, where
we confuse architectural overflow of a counter and perf sampling
period, and uses patch #4 to fix the issue.
I'l planning to send patches 1 through to 3 as fixes shortly, but I
expect the last two patches to require more discussions.
Marc Zyngier (5):
KVM: arm64: pmu: Fix cycle counter truncation
arm64: KVM: Handle PMCR_EL0.LC as RES1 on pure AArch64 systems
KVM: arm64: pmu: Set the CHAINED attribute before creating the
in-kernel event
arm64: perf: Add reload-on-overflow capability
KVM: arm64: pmu: Reset sample period on overflow handling
arch/arm64/include/asm/perf_event.h | 4 +++
arch/arm64/kernel/perf_event.c | 8 ++++-
arch/arm64/kvm/sys_regs.c | 4 +++
virt/kvm/arm/pmu.c | 45 +++++++++++++++++++----------
4 files changed, 45 insertions(+), 16 deletions(-)
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2.20.1
