[PATCH v3 6/9] kvm: arm/arm64: Add host pmu to support VM introspection

Hi Marc,

Marc Zyngier [off-list ref] writes:

+Mark

On 10/01/17 11:38, Punit Agrawal wrote:

quoted

Both AArch32 and AArch64 mode of the ARMv8 architecture support trapping
certain VM operations, e.g, TLB and cache maintenance
operations. Selective trapping of these operations for specific VMs can
be used to track the frequency with which these occur during execution.

Add a software PMU on the host that can support tracking VM
operations (in the form of PMU events). Supporting new events requires
providing callbacks to configure the VM to enable/disable the trapping
and read a count of the frequency.

The host PMU events can be controlled by tools like perf that use
standard kernel perf interfaces.

Signed-off-by: Punit Agrawal <redacted>
Cc: Christoffer Dall <redacted>
Cc: Marc Zyngier <redacted>
Cc: Will Deacon <redacted>
---
 arch/arm/include/asm/kvm_host.h   |   8 ++
 arch/arm/kvm/arm.c                |   2 +
 arch/arm64/include/asm/kvm_host.h |   8 ++
 virt/kvm/arm/host_pmu.c           | 272 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 290 insertions(+)
 create mode 100644 virt/kvm/arm/host_pmu.c

[...]

quoted

This patch really makes me think that there is nothing arm-specific in
here at all. Why can't it be a generic feature through which
architectures can expose events in a generic way (or as close as
possible to being generic)?

I wasn't sure if other architectures are interested in the functionality
- that's the only reason. Having said that, it can be turned off in the
config so there shouldn't be any complaints.

I'll move this to virt/kvm in the next incarnation.

Thanks for taking a look.

Thanks,

	M.