linux-kernel - [PATCH v2 5/6] KVM: s390: interrupt: Fix single-stepping ISKE

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Message-ID: <20230721120046.2262291-6-iii@linux.ibm.com>
Date:   Fri, 21 Jul 2023 13:57:58 +0200
From:   Ilya Leoshkevich <iii@...ux.ibm.com>
To:     Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>
Cc:     David Hildenbrand <david@...hat.com>,
        Sven Schnelle <svens@...ux.ibm.com>, kvm@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jens Freimann <jfreimann@...hat.com>,
        Ilya Leoshkevich <iii@...ux.ibm.com>
Subject: [PATCH v2 5/6] KVM: s390: interrupt: Fix single-stepping ISKE

kvm_s390_skey_check_enable() does not emulate any instructions, rather,
it clears CPUSTAT_KSS and arranges for ISKE to run again. Therefore,
skip the PER check and let ISKE run happen. Otherwise a debugger will
see two single-step events on the same ISKE.

Signed-off-by: Ilya Leoshkevich <iii@...ux.ibm.com>
---
 arch/s390/kvm/intercept.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index d2f7940c5d03..8793cec066a6 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -630,8 +630,7 @@ 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;
+		return kvm_s390_skey_check_enable(vcpu);
 	case ICPT_MCHKREQ:
 	case ICPT_INT_ENABLE:
 		/*
-- 
2.41.0