From: Christian Borntraeger borntraeger@de.ibm.com
commit 5615e74f48dcc982655543e979b6c3f3f877e6f6 upstream.
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 # v5.3+ Fixes: e5282de93105 ("s390: ap: kvm: add PQAP interception for AQIC") Link: https://lore.kernel.org/kvm/20200505083515.2720-1-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 Signed-off-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/kvm/priv.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/s390/kvm/priv.c +++ b/arch/s390/kvm/priv.c @@ -626,10 +626,12 @@ static int handle_pqap(struct kvm_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 */