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authorZachary Amsden <zamsden@redhat.com>2010-09-18 14:38:12 -1000
committerAvi Kivity <avi@redhat.com>2010-10-24 10:52:56 +0200
commit28e4639adf0c9f26f6bb56149b7ab547bf33bb95 (patch)
tree0d20f168f33bc0165ee4a9d18c386a7cdbad63c4 /arch/x86
parent0959ffacf39b1ae7f56072b0c64429ee528100ca (diff)
KVM: x86: Fix kvmclock bug
If preempted after kvmclock values are updated, but before hardware virtualization is entered, the last tsc time as read by the guest is never set. It underflows the next time kvmclock is updated if there has not yet been a successful entry / exit into hardware virt. Fix this by simply setting last_tsc to the newly read tsc value so that any computed nsec advance of kvmclock is nulled. Signed-off-by: Zachary Amsden <zamsden@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kvm/x86.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a51635ee85e..0b021e16f9d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1095,6 +1095,7 @@ static int kvm_write_guest_time(struct kvm_vcpu *v)
vcpu->hv_clock.tsc_timestamp = tsc_timestamp;
vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset;
vcpu->last_kernel_ns = kernel_ns;
+ vcpu->last_guest_tsc = tsc_timestamp;
vcpu->hv_clock.flags = 0;
/*