[PATCH v3 5/6] KVM: s390: interrupt: Fix single-stepping keyless mode exits

Ilya Leoshkevich
2023-07-24T09:50:38Z

kvm_s390_skey_check_enable() does not emulate any instructions, rather,
it clears CPUSTAT_KSS and arranges the instruction that caused the exit
(e.g., ISKE, SSKE, RRBE or LPSWE with a keyed PSW) to run again.

Therefore, skip the PER check and let the instruction execution happen.
Otherwise, a debugger will see two single-step events on the same
instruction.

Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
arch/s390/kvm/intercept.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index d2f7940c5d03..62b3b956c843 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -630,8 +630,8 @@ int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
rc = handle_partial_execution(vcpu);
break;
case ICPT_KSS:
- rc = kvm_s390_skey_check_enable(vcpu);
- break;
+ /* Instruction will be redriven, skip the PER check. */
+ return kvm_s390_skey_check_enable(vcpu);
case ICPT_MCHKREQ:
case ICPT_INT_ENABLE:
/*
--
2.41.0