Re: [Qemu-arm] [PATCH V6 0/2] Add option to configure guest vPMU

[Wei Huang]

On 10/04/2016 04:38 PM, Wei Huang wrote:
> 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-2.8/virt,accel=kvm -cpu host               NO     NO
>   -M virt-2.8/virt,accel=kvm -cpu host,pmu=off       NO     NO
>   -M virt-2.8/virt,accel=kvm -cpu host,pmu=on        YES    NO

Hi Peter,

I just updated this patchset to comply with the recent addition of 2.8
machine type. Please let me know if you have any comments.

>   -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-2.8/virt,accel=tcg -cpu cortex-a57         NO     NO
>   -M virt-2.8/virt,accel=tcg -cpu cortex-a57,pmu=off NO     NO
>   -M virt-2.8/virt,accel=tcg -cpu cortex-a57,pmu=on  NO     "No KVM"
>   -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-2.8/virt,accel=tcg -cpu cortex-a15         NO     NO
>   -M virt-2.8/virt,accel=tcg -cpu cortex-a15,pmu=off NO     "No PMU property"
>   -M virt-2.8/virt,accel=tcg -cpu cortex-a15,pmu=on  NO     "No PMU property"
>   -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
> 
> V5->V6:
>   * adapt patches for new machine type 2.8
> 
> 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            | 19 ++++++++++++++++++-
>  target-arm/cpu.c         | 23 +++++++++++++++++++++++
>  target-arm/cpu.h         |  3 ++-
>  target-arm/cpu64.c       |  2 ++
>  target-arm/kvm64.c       | 17 ++++++++++++++---
>  6 files changed, 60 insertions(+), 6 deletions(-)
>