[J][PATCH 1/1] KVM: s390: add debug statement for diag 318 CPNC data

[frank.heimes at canonical.com]

From: Collin Walling <walling at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1953334

The diag 318 data contains values that denote information regarding the
guest's environment. Currently, it is unecessarily difficult to observe
this value (either manually-inserted debug statements, gdb stepping, mem
dumping etc). It's useful to observe this information to obtain an
at-a-glance view of the guest's environment, so lets add a simple VCPU
event that prints the CPNC to the s390dbf logs.

Signed-off-by: Collin Walling <walling at linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger at de.ibm.com>
Link: https://lore.kernel.org/r/20211027025451.290124-1-walling@linux.ibm.com
[borntraeger at de.ibm.com]: change debug level to 3
Signed-off-by: Christian Borntraeger <borntraeger at de.ibm.com>
(cherry picked from commit 3fd8417f2c728d810a3b26d7e2008012ffb7fd01)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
---
 arch/s390/kvm/kvm-s390.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 1c97493d21e1..db20025b7e9d 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4255,6 +4255,7 @@ static void sync_regs_fmt2(struct kvm_vcpu *vcpu)
 	if (kvm_run->kvm_dirty_regs & KVM_SYNC_DIAG318) {
 		vcpu->arch.diag318_info.val = kvm_run->s.regs.diag318;
 		vcpu->arch.sie_block->cpnc = vcpu->arch.diag318_info.cpnc;
+		VCPU_EVENT(vcpu, 3, "setting cpnc to %d", vcpu->arch.diag318_info.cpnc);
 	}
 	/*
 	 * If userspace sets the riccb (e.g. after migration) to a valid state,
-- 
2.25.1