KVM: x86: TSC reset compensation

Attempt to synchronize TSCs which are reset to the same value.  In the
case of a reliable hardware TSC, we can just re-use the same offset, but
on non-reliable hardware, we can get closer by adjusting the offset to
match the elapsed time.

Signed-off-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a215153f1ff..57b4394491e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -396,6 +396,9 @@ struct kvm_arch {
         unsigned long irq_sources_bitmap;
         s64 kvmclock_offset;
         spinlock_t tsc_write_lock;
+        u64 last_tsc_nsec;
+        u64 last_tsc_offset;
+        u64 last_tsc_write;
 
         struct kvm_xen_hvm_config xen_hvm_config;