[PATCH v4 00/10] make L2's kvm-clock stable, get rid of pvclock_gtod_copy in KVM

Denis Plotnikov
2017-08-02T14:39:32Z

V4:
* removed "is stable" function with vague definition of stability
there is the only function which does time with cycle stamp getting
* some variables renamed
* some patches split into smaller once
* atomic64_t usage is replaced with atomic_t

V3:
Changing the timekeeper interface for clocksource reading looks like
an overkill to achive the goal of getting cycles stamp for KVM.
Instead extend the timekeeping interface and add functions which provide
necessary data: read clocksource with cycles stamp, check whether the
clock source is stable.

Use those functions and improve existing timekeeper functionality to
replace pvclock_gtod_copy scheme in masterclock data calculation.

V2:
The main goal is to make L2 kvm-clock be stable when it's running over L1
with stable kvm-clock.

The patch series is for x86 architecture only. If the series is approved
I'll do changes for other architectures but I don't have an ability to
compile and check for every single on (help needed)

The patch series do the following:

* change timekeeper interface to get cycles stamp value from
the timekeeper
* get rid of pvclock copy in KVM by using the changed timekeeper
interface: get time and cycles right from the timekeeper
* make KVM recognize a stable kvm-clock as stable clocksource
and use the KVM masterclock in this case, which means making
L2 stable when running over stable L1 kvm-clock

Denis Plotnikov (10):
timekeeper: introduce extended clocksource reading callback
timekeeper: introduce boot field in system_time_snapshot
timekeeper: use the extended reading function on snapshot acquiring
tsc: implement the extended tsc reading function
KVM: x86: switch to masterclock update using timekeeper functionality
timekeeper: add clocksource change notifier
KVM: x86: remove not used pvclock_gtod_copy
pvclock: add parameters to store stamp data in pvclock reading
function
pvclock: add clocksource change notification on changing of tsc stable
bit
kvmclock: implement the extended reading function

arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/include/asm/pvclock.h | 3 +-
arch/x86/kernel/kvmclock.c | 19 +++-
arch/x86/kernel/pvclock.c | 37 +++++-
arch/x86/kernel/tsc.c | 10 ++
arch/x86/kvm/trace.h | 31 ++---
arch/x86/kvm/x86.c | 242 ++++++++--------------------------------
arch/x86/xen/time.c | 2 +-
include/linux/clocksource.h | 11 +-
include/linux/cs_notifier.h | 17 +++
include/linux/timekeeping.h | 5 +
kernel/time/timekeeping.c | 68 ++++++++++-
12 files changed, 219 insertions(+), 228 deletions(-)
create mode 100644 include/linux/cs_notifier.h

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2.7.4