Merge tag 'kvm-s390-next-5.13-2' of git://git.kernel.org/pub/scm/linu…

…x/kernel/git/kvms390/linux into HEAD

KVM: s390: Fix potential crash in preemptible kernels

There is a potential race for preemptible kernels, where
the host kernel would get a fault when it is preempted as
the wrong point in time.

arch/s390/kvm/kvm-s390.c

@@ -4313,16 +4313,16 @@ static void store_regs_fmt2(struct kvm_vcpu *vcpu)
 	kvm_run->s.regs.bpbc = (vcpu->arch.sie_block->fpf & FPF_BPBC) == FPF_BPBC;
 	kvm_run->s.regs.diag318 = vcpu->arch.diag318_info.val;
 	if (MACHINE_HAS_GS) {
+		preempt_disable();
 		__ctl_set_bit(2, 4);
 		if (vcpu->arch.gs_enabled)
 			save_gs_cb(current->thread.gs_cb);
-		preempt_disable();
 		current->thread.gs_cb = vcpu->arch.host_gscb;
 		restore_gs_cb(vcpu->arch.host_gscb);
-		preempt_enable();
 		if (!vcpu->arch.host_gscb)
 			__ctl_clear_bit(2, 4);
 		vcpu->arch.host_gscb = NULL;
+		preempt_enable();
 	}
 	/* SIE will save etoken directly into SDNX and therefore kvm_run */
 }