arm64: Add support for KVM_ARM_VCPU_PMU_V3_SET_PMU
The KVM_ARM_VCPU_PMU_V3_CTRL(KVM_ARM_VCPU_PMU_V3_SET_PMU) VCPU ioctl is
used to assign a physical PMU to the events that KVM creates when emulating
the PMU for that VCPU. This is useful on heterogeneous systems, when there
is more than one hardware PMU present. All VCPUs must have the same PMU
assigned.
The assumption that is made in the implementation is that the user will pin
the kvmtool process on a set of CPUs that share the same PMU. This allows
kvmtool to set the same PMU for all VCPUs from the main thread, instead of
in the individual VCPU threads. If a VCPU thread migrates to a CPU which
has a different a PMU than the CPU on which the main thread was executing
when the PMU was set, the KVM_RUN ioctl will fail with kvm_run.exit_reason
set to KVM_EXIT_FAIL_ENTRY, and kvm_run.fail_entry will be populated with
the physical CPU ID on which the VCPU tried to execute.
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20220412133231.35355-11-alexandru.elisei@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2 files changed
