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 KVM"
-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
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 | 5 +++--
target-arm/cpu64.c | 2 ++
target-arm/kvm64.c | 17 ++++++++++++++---
6 files changed, 60 insertions(+), 7 deletions(-)
--
1.8.3.1
