On 10/31/2011 03:07 PM, Eric B Munson wrote:
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<[email protected]>
---
arch/x86/include/asm/pvclock.h | 2 ++
arch/x86/kernel/kvmclock.c | 19 +++++++++++++++++++
2 files changed, 21 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index c59cc97..7d3ba41 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -13,6 +13,8 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
struct timespec *ts);
void pvclock_resume(void);
+bool kvm_check_and_clear_host_stopped(int cpu);
A kvm-specific function shouldn't be declared in pvclock.h as this is shared
code between KVM and Xen.
+
/*
* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
* yielding a 64-bit result.
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index c1a0188..8ddcfaf 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -113,6 +113,25 @@ static void kvm_get_preset_lpj(void)
preset_lpj = lpj;
}
+bool kvm_check_and_clear_host_stopped(int cpu)
+{
+ bool ret = false;
+ struct pvclock_vcpu_time_info *src;
+
+ /*
+ * per_cpu() is safe here because this function is only called from
+ * timer functions where preemption is already disabled.
+ */
+ WARN_ON(!in_atomic());
+ src =&per_cpu(hv_clock, cpu);
+ if ((src->flags& PVCLOCK_GUEST_STOPPED) != 0) {
+ src->flags = src->flags& (~PVCLOCK_GUEST_STOPPED);
+ ret = true;
+ }
It would be helpful to separate out the patches for guest enablement from host
enablement. This is a guest function, correct?
Don't you need an atomic getandset here? Can the host clear this flag or only
set it?
It's ashame we don't have a proper pvclock spec in Documentation/. I would
suggest at least adding a description of how this bit works in the first patch.
Regards,
Anthony Liguori
+
+ return ret;
+}
+
static struct clocksource kvm_clock = {
.name = "kvm-clock",
.read = kvm_clock_get_cycles,
--
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