Merge tag 'kvm-s390-master-5.7-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Fix for running nested uner z/VM

There are circumstances when running nested under z/VM that would trigger a
WARN_ON_ONCE. Remove the WARN_ON_ONCE. Long term we certainly want to make this
code more robust and flexible, but just returning instead of WARNING makes
guest bootable again.

Author: bonzini

arch/s390/kvm/priv.c

@@ -626,10 +626,12 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
 	 * available for the guest are AQIC and TAPQ with the t bit set
 	 * since we do not set IC.3 (FIII) we currently will only intercept
 	 * the AQIC function code.
+	 * Note: running nested under z/VM can result in intercepts for other
+	 * function codes, e.g. PQAP(QCI). We do not support this and bail out.
 	 */
 	reg0 = vcpu->run->s.regs.gprs[0];
 	fc = (reg0 >> 24) & 0xff;
-	if (WARN_ON_ONCE(fc != 0x03))
+	if (fc != 0x03)
 		return -EOPNOTSUPP;
 
 	/* PQAP instruction is allowed for guest kernel only */