From 53f658b3c33616a4997ee254311b335e59063289 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Thu, 11 Dec 2008 20:45:05 +0100 Subject: KVM: VMX: initialize TSC offset relative to vm creation time VMX initializes the TSC offset for each vcpu at different times, and also reinitializes it for vcpus other than 0 on APIC SIPI message. This bug causes the TSC's to appear unsynchronized in the guest, even if the host is good. Older Linux kernels don't handle the situation very well, so gettimeofday is likely to go backwards in time: http://www.mail-archive.com/kvm@vger.kernel.org/msg02955.html http://sourceforge.net/tracker/index.php?func=detail&aid=2025534&group_id=180599&atid=893831 Fix it by initializating the offset of each vcpu relative to vm creation time, and moving it from vmx_vcpu_reset to vmx_vcpu_setup, out of the APIC MP init path. Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/x86.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 873602b5edfd..3b2acfd72d7f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4170,6 +4170,8 @@ struct kvm *kvm_arch_create_vm(void) /* Reserve bit 0 of irq_sources_bitmap for userspace irq source */ set_bit(KVM_USERSPACE_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap); + rdtscll(kvm->arch.vm_init_tsc); + return kvm; } -- cgit v1.2.2