KVM: Fix kvmclock on !constant_tsc boxes
kvmclock currently falls apart on machines without constant tsc.
This patch fixes it. Changes:
* keep tsc frequency in a per-cpu variable.
* handle kvmclock update using a new request flag, thus checking
whenever we need an update each time we enter guest context.
* use a cpufreq notifier to track frequency changes and force
kvmclock updates.
* send ipis to kick cpu out of guest context if needed to make
sure the guest doesn't see stale values.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 339eda3..18b4df8 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -37,6 +37,7 @@
#define KVM_REQ_PENDING_TIMER 5
#define KVM_REQ_UNHALT 6
#define KVM_REQ_MMU_SYNC 7
+#define KVM_REQ_KVMCLOCK_UPDATE 8
#define KVM_USERSPACE_IRQ_SOURCE_ID 0