KVM: x86: Move TSC reset out of vmcb_init

The VMCB is reset whenever we receive a startup IPI, so Linux is setting
TSC back to zero happens very late in the boot process and destabilizing
the TSC.  Instead, just set TSC to zero once at VCPU creation time.

Why the separate patch?  So git-bisect is your friend.

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

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 12b502de13696e981197e3a35474f14bfad8ca80..81ed28cb36e692eb4413c294408d5498bee876e8 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -766,7 +766,6 @@ static void init_vmcb(struct vcpu_svm *svm)
 
        control->iopm_base_pa = iopm_base;
        control->msrpm_base_pa = __pa(svm->msrpm);
-       control->tsc_offset = 0-native_read_tsc();
        control->int_ctl = V_INTR_MASKING_MASK;
 
        init_seg(&save->es);
@@ -902,6 +901,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
        svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;
        svm->asid_generation = 0;
        init_vmcb(svm);
+       svm->vmcb->control.tsc_offset = 0-native_read_tsc();
 
        err = fx_init(&svm->vcpu);
        if (err)