KVM: nVMX: do not start the preemption timer hrtimer unnecessarily

The preemption timer can be started even if there is a vmentry
failure during or after loading guest state.  That is pointless,
move the call after all conditions have been checked.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 523d30e935e141040a1ad28c274d3cde523696ba..11431bb4c7edc2ab620c92dfd36ca5aaac53765c 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2278,10 +2278,6 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
        }
        vmx_set_rflags(vcpu, vmcs12->guest_rflags);
 
-       vmx->nested.preemption_timer_expired = false;
-       if (nested_cpu_has_preemption_timer(vmcs12))
-               vmx_start_preemption_timer(vcpu);
-
        /* EXCEPTION_BITMAP and CR0_GUEST_HOST_MASK should basically be the
         * bitwise-or of what L1 wants to trap for L2, and what we want to
         * trap. Note that CR0.TS also needs updating - we do this later.
@@ -3018,6 +3014,15 @@ int nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry)
        if (unlikely(evaluate_pending_interrupts))
                kvm_make_request(KVM_REQ_EVENT, vcpu);
 
+       /*
+        * Do not start the preemption timer hrtimer until after we know
+        * we are successful, so that only nested_vmx_vmexit needs to cancel
+        * the timer.
+        */
+       vmx->nested.preemption_timer_expired = false;
+       if (nested_cpu_has_preemption_timer(vmcs12))
+               vmx_start_preemption_timer(vcpu);
+
        /*
         * Note no nested_vmx_succeed or nested_vmx_fail here. At this point
         * we are no longer running L1, and VMLAUNCH/VMRESUME has not yet