From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Janosch Frank <frankja@linux.vnet.ibm.com>
Cc: KVM <kvm@vger.kernel.org>, Cornelia Huck <cohuck@redhat.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
David Hildenbrand <david@redhat.com>,
linux-s390 <linux-s390@vger.kernel.org>,
Qian Cai <cailca@icloud.com>, Pierre Morel <pmorel@linux.ibm.com>,
Tony Krowiak <akrowiak@linux.ibm.com>
Subject: [PATCH v2] KVM: s390: Remove false WARN_ON_ONCE for the PQAP instruction
Date: Tue, 5 May 2020 10:35:15 +0200 [thread overview]
Message-ID: <20200505083515.2720-1-borntraeger@de.ibm.com> (raw)
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 <pmorel@linux.ibm.com>
Cc: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/kvm/20200505073525.2287-1-borntraeger@de.ibm.com
Reported-by: Qian Cai <cailca@icloud.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
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
next reply other threads:[~2020-05-05 8:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 8:35 Christian Borntraeger [this message]
2020-05-05 8:46 ` [PATCH v2] KVM: s390: Remove false WARN_ON_ONCE for the PQAP instruction Cornelia Huck
2020-05-05 8:47 ` David Hildenbrand
2020-05-05 9:15 ` Christian Borntraeger
2020-05-05 15:03 ` Qian Cai
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