Commit 387cb8e8 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

Merge tag 'kvm-s390-next-5.13-2' of... 

Merge tag 'kvm-s390-next-5.13-2' of git://git.kernel.org/pub/scm/linux/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.
parents 6c377b02 44bada28

arch/s390/kvm/kvm-s390.c

+2 −2
Original line number Diff line number Diff line
@@ -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 */

}