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Tue, 29 Aug 2023 12:09:20 +0000 (GMT) From: Janosch Frank To: pbonzini@redhat.com Cc: kvm@vger.kernel.org, frankja@linux.ibm.com, david@redhat.com, borntraeger@linux.ibm.com, cohuck@redhat.com, linux-s390@vger.kernel.org, imbrenda@linux.ibm.com, hca@linux.ibm.com, mihajlov@linux.ibm.com, seiden@linux.ibm.com, akrowiak@linux.ibm.com, seanjc@google.com Subject: [GIT PULL v2 03/10] KVM: s390: interrupt: Fix single-stepping kernel-emulated instructions Date: Tue, 29 Aug 2023 14:03:58 +0200 Message-ID: <20230829120843.66637-4-frankja@linux.ibm.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230829120843.66637-1-frankja@linux.ibm.com> References: <20230829120843.66637-1-frankja@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: nSj9dow4a9ZvaouLnMokPJyC-EPusPkW X-Proofpoint-ORIG-GUID: j6sy5BW1zpmAPO7CB5FyfFiGY0ioXvFw X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.957,Hydra:6.0.601,FMLib:17.11.176.26 definitions=2023-08-29_09,2023-08-29_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 mlxlogscore=675 suspectscore=0 bulkscore=0 spamscore=0 malwarescore=0 priorityscore=1501 lowpriorityscore=0 phishscore=0 mlxscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2308100000 definitions=main-2308290105 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Ilya Leoshkevich Single-stepping a kernel-emulated instruction that generates an interrupt causes GDB to land on the instruction following it instead of the respective interrupt handler. The reason is that kvm_handle_sie_intercept(), after injecting the interrupt, also processes the PER event and arranges a KVM_SINGLESTEP exit. The interrupt is not yet delivered, however, so the userspace sees the next instruction. Fix by avoiding the KVM_SINGLESTEP exit when there is a pending interrupt. The next __vcpu_run() loop iteration will arrange a KVM_SINGLESTEP exit after delivering the interrupt. Reviewed-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Signed-off-by: Ilya Leoshkevich Message-ID: <20230725143857.228626-4-iii@linux.ibm.com> Signed-off-by: Claudio Imbrenda Signed-off-by: Janosch Frank --- arch/s390/kvm/intercept.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c index e54496740859..db222c749e5e 100644 --- a/arch/s390/kvm/intercept.c +++ b/arch/s390/kvm/intercept.c @@ -583,6 +583,19 @@ static int handle_pv_notification(struct kvm_vcpu *vcpu) return handle_instruction(vcpu); } +static bool should_handle_per_ifetch(const struct kvm_vcpu *vcpu, int rc) +{ + /* Process PER, also if the instruction is processed in user space. */ + if (!(vcpu->arch.sie_block->icptstatus & 0x02)) + return false; + if (rc != 0 && rc != -EOPNOTSUPP) + return false; + if (guestdbg_sstep_enabled(vcpu) && vcpu->arch.local_int.pending_irqs) + /* __vcpu_run() will exit after delivering the interrupt. */ + return false; + return true; +} + int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu) { int rc, per_rc = 0; @@ -645,9 +658,7 @@ int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu) return -EOPNOTSUPP; } - /* process PER, also if the instruction is processed in user space */ - if (vcpu->arch.sie_block->icptstatus & 0x02 && - (!rc || rc == -EOPNOTSUPP)) + if (should_handle_per_ifetch(vcpu, rc)) per_rc = kvm_s390_handle_per_ifetch_icpt(vcpu); return per_rc ? per_rc : rc; }