[PATCH] KVM: s390: Remove false WARN_ON_ONCE for the PQAP instruction

Christian Borntraeger
2020-05-05T07:35:33Z

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, for example 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>
Reported-by: Qian Cai <cailca@icloud.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.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..bbe46c6aedbf 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, e.g.
+ * for 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