[PATCH v3 3/5] KVM: arm64: Add PMU event filtering infrastructure

[Andrew Jones]

On Tue, Sep 08, 2020 at 08:58:28AM +0100, Marc Zyngier wrote:
> It can be desirable to expose a PMU to a guest, and yet not want the
> guest to be able to count some of the implemented events (because this
> would give information on shared resources, for example.
> 
> For this, let's extend the PMUv3 device API, and offer a way to setup a
> bitmap of the allowed events (the default being no bitmap, and thus no
> filtering).
> 
> Userspace can thus allow/deny ranges of event. The default policy
> depends on the "polarity" of the first filter setup (default deny if the
> filter allows events, and default allow if the filter denies events).
> This allows to setup exactly what is allowed for a given guest.
> 
> Note that although the ioctl is per-vcpu, the map of allowed events is
> global to the VM (it can be setup from any vcpu until the vcpu PMU is
> initialized).
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/include/asm/kvm_host.h |  5 +++
>  arch/arm64/include/uapi/asm/kvm.h | 16 +++++++
>  arch/arm64/kvm/arm.c              |  2 +
>  arch/arm64/kvm/pmu-emul.c         | 70 ++++++++++++++++++++++++++++---
>  4 files changed, 87 insertions(+), 6 deletions(-)
> 

Reviewed-by: Andrew Jones <drjones at redhat.com>