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Re: [Qemu-arm] [PATCH V1 1/1] arm64: Add an option to turn on/off host-b
From: |
Wei Huang |
Subject: |
Re: [Qemu-arm] [PATCH V1 1/1] arm64: Add an option to turn on/off host-backed vPMU support |
Date: |
Mon, 15 Aug 2016 11:12:53 -0500 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 |
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 <address@hidden>
>> ---
>> 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
>