kvm: x86: Set last_vmentry_cpu in vcpu_enter_guest

Since this field is now in kvm_vcpu_arch, clean things up a little by
setting it in vendor-agnostic code: vcpu_enter_guest. Note that it
must be set after the call to kvm_x86_ops.run(), since it can't be
updated before pre_sev_run().
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Message-Id: <20200603235623.245638-7-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/svm.c

@@ -3398,7 +3398,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
 	 */
 	x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl);
 
-	vcpu->arch.last_vmentry_cpu = vcpu->cpu;
 	__svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&svm->vcpu.arch.regs);
 
 #ifdef CONFIG_X86_64

arch/x86/kvm/vmx/vmx.c

@@ -6740,7 +6740,6 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	if (vcpu->arch.cr2 != read_cr2())
 		write_cr2(vcpu->arch.cr2);
 
-	vcpu->arch.last_vmentry_cpu = vcpu->cpu;
 	vmx->fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
 				   vmx->loaded_vmcs->launched);
 

arch/x86/kvm/x86.c

@@ -8583,6 +8583,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	if (hw_breakpoint_active())
 		hw_breakpoint_restore();
 
+	vcpu->arch.last_vmentry_cpu = vcpu->cpu;
 	vcpu->arch.last_guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc());
 
 	vcpu->mode = OUTSIDE_GUEST_MODE;