From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:48750 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725320AbgEEIfW (ORCPT ); Tue, 5 May 2020 04:35:22 -0400 From: Christian Borntraeger Subject: [PATCH v2] KVM: s390: Remove false WARN_ON_ONCE for the PQAP instruction Date: Tue, 5 May 2020 10:35:15 +0200 Message-Id: <20200505083515.2720-1-borntraeger@de.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Janosch Frank Cc: KVM , Cornelia Huck , Christian Borntraeger , David Hildenbrand , linux-s390 , Qian Cai , Pierre Morel , Tony Krowiak In LPAR we will only get an intercept for FC==3 for the PQAP instruction. Running nested under z/VM can result in other intercepts as well as ECA_APIE is an effective bit: If one hypervisor layer has turned this bit off, the end result will be that we will get intercepts for all function codes. Usually the first one will be a query like PQAP(QCI). So the WARN_ON_ONCE is not right. Let us simply remove it. Cc: Pierre Morel Cc: Tony Krowiak Cc: stable@vger.kernel.org Link: https://lore.kernel.org/kvm/20200505073525.2287-1-borntraeger@de.ibm.com Reported-by: Qian Cai Signed-off-by: Christian Borntraeger Reviewed-by: David Hildenbrand Reviewed-by: Cornelia Huck --- arch/s390/kvm/priv.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c index 69a824f9ef0b..893893642415 100644 --- a/arch/s390/kvm/priv.c +++ b/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 */ -- 2.25.4