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

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.

diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 69a824f..8938936 100644 (file)
--- 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 */