Re: [RFC PATCH 0/2] make L2 kvm-clock stable

[Denis Plotnikov <dplotnikov@virtuozzo.com>]

ping! ping!

On 03.07.2017 19:12, Denis Plotnikov wrote:
> ping!
> 
> On 28.06.2017 13:54, Denis Plotnikov wrote:
>> The goal of the series is to make L2's kvm-clock guest stable when 
>> possible.
>>
>> It's possible when the L2 is running over L1 with a stable 
>> paravirtualized
>> clocksource.
>>
>> To acomplish the goal I can see two approaches:
>>
>> 1. Use currently existing in KVM "monotonic timekeeper shadow".
>>
>>     This approach repeats functionality of time calculation from the 
>> kerenl
>>     monotonic timekeeper. To acomplish the goal it's needed to add time
>>     calculation functions for paravirtualized clocksources to KVM which
>>     implies repeating the functionality from the timekeeper.
>>     It seems to me that this approach is not the best one because of code
>>     repetition, data shadowing, keeping logic consistent with 
>> timekeeper's one.
>>     I would consider using the next approach.
>>
>> 2. Use existing timekeeper functionality with extended interface
>>
>>     This approach deligates all time related calculations to the kernel
>>     timekeeper instead of having timekeeper shadow and time 
>> calculating logic
>>     in KVM.
>>     Using this approach will allow to remove the monotonic timekeeping 
>> shadow,
>>     but ask to change timekeeper interface in a way that will add an 
>> ability
>>     to return the timestamp value used for time calculations (if any) 
>> because this
>>     value is needed in KVM (and possibly somewhere else in the future).
>>
>> This patch series implements the 2nd approach (for now, for x86 only).
>> Could you please give me some feedback about it?
>>
>> Denis Plotnikov (2):
>>    timekeeper: change interface of clocksource reding functions
>>    KVM: x86: add support of kvm-clock stablity in L2
>>
>>   arch/x86/hyperv/hv_init.c           |   4 +-
>>   arch/x86/include/asm/kvm_host.h     |   2 +-
>>   arch/x86/include/asm/pvclock.h      |   2 +-
>>   arch/x86/kernel/hpet.c              |   4 +-
>>   arch/x86/kernel/kvmclock.c          |  19 ++-
>>   arch/x86/kernel/pvclock.c           |  11 +-
>>   arch/x86/kernel/tsc.c               |   7 +-
>>   arch/x86/kvm/x86.c                  | 294 
>> ++++++++++--------------------------
>>   arch/x86/lguest/boot.c              |   2 +-
>>   arch/x86/platform/uv/uv_time.c      |  10 +-
>>   arch/x86/xen/time.c                 |  21 ++-
>>   arch/x86/xen/xen-ops.h              |   2 +-
>>   drivers/clocksource/acpi_pm.c       |  12 +-
>>   drivers/hv/hv_util.c                |   6 +-
>>   include/linux/clocksource.h         |   9 +-
>>   include/linux/timekeeper_internal.h |   2 +-
>>   include/linux/timekeeping.h         |  34 ++++-
>>   kernel/time/clocksource.c           |   4 +-
>>   kernel/time/jiffies.c               |   2 +-
>>   kernel/time/timekeeping.c           |  66 +++++---
>>   20 files changed, 221 insertions(+), 292 deletions(-)
>>
> 

-- 
Best,
Denis