Merge tag 'kvm-s390-master-4.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux
KVM: s390: Fix for user-triggerable WARN_ON
A malicious user space can provide an invalid mode for runtime
instrumentation via the interfaces that are normally used on
the target host during migration. This would trigger a WARN_ON
via validity intercept. Let's detect this special case.
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 1cab8a1..7a27eeb 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -119,8 +119,13 @@ static int handle_validity(struct kvm_vcpu *vcpu)
vcpu->stat.exit_validity++;
trace_kvm_s390_intercept_validity(vcpu, viwhy);
- WARN_ONCE(true, "kvm: unhandled validity intercept 0x%x\n", viwhy);
- return -EOPNOTSUPP;
+ KVM_EVENT(3, "validity intercept 0x%x for pid %u (kvm 0x%pK)", viwhy,
+ current->pid, vcpu->kvm);
+
+ /* do not warn on invalid runtime instrumentation mode */
+ WARN_ONCE(viwhy != 0x44, "kvm: unhandled validity intercept 0x%x\n",
+ viwhy);
+ return -EINVAL;
}
static int handle_instruction(struct kvm_vcpu *vcpu)