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KVM: x86: limit difference between kvmclock updates

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kvmclock updates which are isolated to a given vcpu, such as vcpu->cpu
migration, should not allow system_timestamp from the rest of the vcpus
to remain static. Otherwise ntp frequency correction applies to one
vcpu's system_timestamp but not the others.

So in those cases, request a kvmclock update for all vcpus. The worst
case for a remote vcpu to update its kvmclock is then bounded by maximum
nohz sleep latency.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
This commit is contained in:
Marcelo Tosatti 2013-05-09 20:21:41 -03:00 • committed by Gleb Natapov
parent f1ed0450a5
commit 0061d53daf
2 changed files with 29 additions and 2 deletions
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include/linux/kvm_host.h
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@ -124,6 +124,7 @@ static inline bool is_error_page(struct page *page)
#define KVM_REQ_MCLOCK_INPROGRESS 19
#define KVM_REQ_EPR_EXIT 20
#define KVM_REQ_SCAN_IOAPIC 21
#define KVM_REQ_GLOBAL_CLOCK_UPDATE 22
#define KVM_USERSPACE_IRQ_SOURCE_ID 0
#define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1