[Qemu-devel] [PATCH V5 0/2] Add option to configure guest vPMU

[Wei Huang <wei@redhat.com>]

This patchset adds a pmu=[on/off] option to enable/disable vPMU support 
for guest VM. There are several reasons to justify this option. First,
vPMU can be problematic for cross-migration between different SoC as perf
counters are architecture-dependent. It is more flexible to have an option
to turn it on/off. Secondly this option matches the "pmu" option as
supported in libvirt. To make sure backward compatible, a PMU-related
property is added to mach-virt machine types.

The following are testing results with this patchset. Other combinations
should have similar results:
    CONFIG (qemu-system-aarch64)                    vPMU   WARNING
    -M virt-2.7,accel=kvm -cpu host                  YES    NO
    -M virt-2.7,accel=kvm -cpu host,pmu=off          NO     NO
    -M virt-2.7,accel=kvm -cpu host,pmu=on           YES    NO
    -M virt-2.6,accel=kvm -cpu host                  NO     NO
    -M virt-2.6,accel=kvm -cpu host,pmu=off          NO     NO
    -M virt-2.6,accel=kvm -cpu host,pmu=on           YES    NO

    -M virt-2.7,accel=tcg -cpu cortex-a57            NO     NO
    -M virt-2.7,accel=tcg -cpu cortex-a57,pmu=off    NO     NO
    -M virt-2.7,accel=tcg -cpu cortex-a57,pmu=on     NO     "No KVM"
    -M virt-2.6,accel=tcg -cpu cortex-a57            NO     NO
    -M virt-2.6,accel=tcg -cpu cortex-a57,pmu=off    NO     NO
    -M virt-2.6,accel=tcg -cpu cortex-a57,pmu=on     NO     "No KVM"

    -M virt-2.7,accel=tcg -cpu cortex-a15            NO     NO
    -M virt-2.7,accel=tcg -cpu cortex-a15,pmu=off    NO     "No PMU property"
    -M virt-2.7,accel=tcg -cpu cortex-a15,pmu=on     NO     "No PMU property"
    -M virt-2.6,accel=tcg -cpu cortex-a15            NO     NO
    -M virt-2.6,accel=tcg -cpu cortex-a15,pmu=off    NO     "No PMU property"
    -M virt-2.6,accel=tcg -cpu cortex-a15,pmu=on     NO     "No PMU property"

    * "NO KVM" msg
      warning: pmu can't be enabled without KVM acceleration
    * "No PMU property" msg
      can't apply global cortex-a15-arm-cpu.pmu=off: Property '.pmu' not found

V4->V5:
  * remove comment change for has_pmu
  * remove warning msg when pmu_default_on=TRUE && has_pmu=AUTO && tcg=TRUE

V3->V4:
  * change has_pmu from Boolean to OnOffAuto to handle different cases
  * "pmu" property is re-defined as DEFINE_PROP_ON_OFF_AUTO

V2->V3:
  * revise patch 1 commit msg and if-else statement (Drew) 
  * move property field into VirtMachineClass (Drew)

V1->V2:
  * keep the original field name as "has_pmu"
  * add a warning message when PMU is turned on without KVM
  * use the feature bit to check PMU availability, instead of using has_pmu
  * add PMU compat support to mach-virt machine type

RFC->V1:
  * set default pmu=off
  * change struct ARMCPU field name "has_pmu" ==> "has_host_pmu"
  * like el3, add a new feature ARM_FEATURE_HOST_PMU
  * "pmu" property becomes CPU dependent. Only cortex-a53/cortex-a57/host
    running on kvm supports this option.

Thanks,
-Wei

Wei Huang (2):
  arm64: Add an option to turn on/off vPMU support
  arm: virt: add PMU property to mach-virt machine type

 hw/arm/virt-acpi-build.c |  2 +-
 hw/arm/virt.c            | 18 +++++++++++++++++-
 target-arm/cpu.c         | 23 +++++++++++++++++++++++
 target-arm/cpu.h         |  3 ++-
 target-arm/cpu64.c       |  2 ++
 target-arm/kvm64.c       | 17 ++++++++++++++---
 6 files changed, 59 insertions(+), 6 deletions(-)

-- 
1.8.3.1