linux-stable.git/arch/x86/kernel/kvmclock.c, branch v3.8

x86: kvm guest: pvclock vsyscall support

2012-11-28T01:29:10+00:00

Hook into generic pvclock vsyscall code, with the aim to
allow userspace to have visibility into pvclock data.

Signed-off-by: Marcelo Tosatti

x86: kvmclock: allocate pvclock shared memory area

2012-11-28T01:29:05+00:00

We want to expose the pvclock shared memory areas, which
the hypervisor periodically updates, to userspace.

For a linear mapping from userspace, it is necessary that
entire page sized regions are used for array of pvclock
structures.

There is no such guarantee with per cpu areas, therefore move
to memblock_alloc based allocation.

Acked-by: Glauber Costa 
Signed-off-by: Marcelo Tosatti

x86: kvmclock: remove check_and_clear_guest_paused warning

2012-06-12T02:18:33+00:00

CPU offline path calls the hrtimer interrupt handler with interrupts
disabled, without touching preempt_count, triggering this warning.

Remove the warning since it is supposed to be used from hrtimer
interrupt context only.

Signed-off-by: Marcelo Tosatti

kvmclock: remove unneeded EXPORT macro

2012-04-08T09:49:54+00:00

check_and_clear_guest_paused does not need to be exported as it isn't used
by any modules, remove the export.

Signed-off-by: Eric B Munson 
Signed-off-by: Marcelo Tosatti 
Signed-off-by: Avi Kivity

kvmclock: Add functions to check if the host has stopped the vm

2012-04-08T09:48:59+00:00

When a host stops or suspends a VM it will set a flag to show this.  The
watchdog will use these functions to determine if a softlockup is real, or the
result of a suspended VM.

Signed-off-by: Eric B Munson 
asm-generic changes Acked-by: Arnd Bergmann 
Signed-off-by: Marcelo Tosatti 
Signed-off-by: Avi Kivity

x86: kvmclock: abstract save/restore sched_clock_state

2012-03-20T10:37:45+00:00

Upon resume from hibernation, CPU 0's hvclock area contains the old
values for system_time and tsc_timestamp. It is necessary for the
hypervisor to update these values with uptodate ones before the CPU uses
them.

Abstract TSC's save/restore sched_clock_state functions and use
restore_state to write to KVM_SYSTEM_TIME MSR, forcing an update.

Also move restore_sched_clock_state before __restore_processor_state,
since the later calls CONFIG_LOCK_STAT's lockstat_clock (also for TSC).
Thanks to Igor Mammedov for tracking it down.

Fixes suspend-to-disk with kvmclock.

Reviewed-by: Thomas Gleixner 
Signed-off-by: Marcelo Tosatti 
Signed-off-by: Avi Kivity

x86: Introduce x86_cpuinit.early_percpu_clock_init hook

2012-03-05T12:57:32+00:00

When kvm guest uses kvmclock, it may hang on vcpu hot-plug.
This is caused by an overflow in pvclock_get_nsec_offset,

    u64 delta = tsc - shadow->tsc_timestamp;

which in turn is caused by an undefined values from percpu
hv_clock that hasn't been initialized yet.
Uninitialized clock on being booted cpu is accessed from
   start_secondary
    -> smp_callin
      ->  smp_store_cpu_info
        -> identify_secondary_cpu
          -> mtrr_ap_init
            -> mtrr_restore
              -> stop_machine_from_inactive_cpu
                -> queue_stop_cpus_work
                  ...
                    -> sched_clock
                      -> kvm_clock_read
which is well before x86_cpuinit.setup_percpu_clockev call in
start_secondary, where percpu clock is initialized.

This patch introduces a hook that allows to setup/initialize
per_cpu clock early and avoid overflow due to reading
  - undefined values
  - old values if cpu was offlined and then onlined again

Another possible early user of this clock source is ftrace that
accesses it to get timestamps for ring buffer entries. So if
mtrr_ap_init is moved from identify_secondary_cpu to past
x86_cpuinit.setup_percpu_clockev in start_secondary, ftrace
may cause the same overflow/hang on cpu hot-plug anyway.

More complete description of the problem:
  https://lkml.org/lkml/2012/2/2/101

Credits to Marcelo Tosatti  for hook idea.

Acked-by: Thomas Gleixner 
Signed-off-by: Igor Mammedov 
Signed-off-by: Marcelo Tosatti 
Signed-off-by: Avi Kivity

KVM guest: prevent tracing recursion with kvmclock

2011-11-20T08:53:48+00:00

Prevent tracing of preempt_disable() in get_cpu_var() in
kvm_clock_read(). When CONFIG_DEBUG_PREEMPT is enabled,
preempt_disable/enable() are traced and this causes the function_graph
tracer to go into an infinite recursion. By open coding the
preempt_disable() around the get_cpu_var(), we can use the notrace
version which prevents preempt_disable/enable() from being traced and
prevents the recursion.

Based on a similar patch for Xen from Jeremy Fitzhardinge.

Tested-by: Gleb Natapov 
Acked-by: Steven Rostedt 
Signed-off-by: Avi Kivity

KVM guest: KVM Steal time registration

2011-07-24T08:49:36+00:00

This patch implements the kvm bits of the steal time infrastructure.
The most important part of it, is the steal time clock. It is an
continuous clock that shows the accumulated amount of steal time
since vcpu creation. It is supposed to survive cpu offlining/onlining.

[marcelo: fix build with CONFIG_KVM_GUEST=n]

Signed-off-by: Glauber Costa 
Acked-by: Rik van Riel 
Tested-by: Eric B Munson 
CC: Jeremy Fitzhardinge 
CC: Peter Zijlstra 
CC: Avi Kivity 
CC: Anthony Liguori 
Signed-off-by: Avi Kivity 
Signed-off-by: Marcelo Tosatti

x86: Convert remaining x86 clocksources to clocksource_register_hz/khz

2011-02-21T21:33:33+00:00

This converts the remaining x86 clocksources to use
clocksource_register_hz/khz.

CC: jacob.jun.pan@intel.com
CC: Glauber Costa 
CC: Dimitri Sivanich 
CC: Rusty Russell 
CC: Jeremy Fitzhardinge 
CC: Chris McDermott 
CC: Thomas Gleixner 
Tested-by: Konrad Rzeszutek Wilk  [xen]
Signed-off-by: John Stultz