Re: [Qemu-arm] [PATCH V1 1/1] arm64: Add an option to turn on/off host-backed vPMU support

[Wei Huang <wei@redhat.com>]

On 8/15/16 04:31, Andrea Bolognani wrote:
> 
> On Sat, 2016-08-13 at 00:52 -0500, Wei Huang wrote:
>> This patch adds a pmu=[on/off] option to enable/disable host vPMU
>> support in guest VM. There are several reasons to justify this option.
>> First, host-backed 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 tool.
>>  
>> Note that, like "has_el3", the "pmu" option is only made available on
>> CPUs that support host-backed vPMU. They include:
>>      * cortex-a53 + kvm
>>      * cortex-a57 + kvm
>>      * host + kvm
>> This option is removed in other configs where it doesn't make sense
>> (e.g. cortex-a57 + TCG); and the default pmu support is off. This patch
>> has been tested under both DT/ACPI modes.
>>  
>> Signed-off-by: Wei Huang <wei@redhat.com>
>> ---
>>   hw/arm/virt-acpi-build.c |  2 +-
>>   hw/arm/virt.c            |  2 +-
>>   target-arm/cpu.c         | 13 +++++++++++++
>>   target-arm/cpu.h         |  3 ++-
>>   target-arm/cpu64.c       |  6 ++++++
>>   target-arm/kvm64.c       | 10 +++++-----
>>   6 files changed, 28 insertions(+), 8 deletions(-)
> 
> Did you already try driving this with libvirt? It should work
> out of the box.
> 
> If you haven't, I will do it :)

No, I haven't. All tests were done based on command line to QEMU. :-)

-Wei

> 
> -- 
> Andrea Bolognani / Red Hat / Virtualization
>