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Mon, 1 Jun 2026 15:29:52 +0000 (GMT) From: Claudio Imbrenda To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@kernel.org, seiden@linux.ibm.com, nrb@linux.ibm.com, schlameuss@linux.ibm.com, gra@linux.ibm.com Subject: [PATCH v2 6/8] KVM: s390: Fix fault-in code Date: Mon, 1 Jun 2026 17:29:49 +0200 Message-ID: <20260601152951.196859-7-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260601152951.196859-1-imbrenda@linux.ibm.com> References: <20260601152951.196859-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjAxMDE1MSBTYWx0ZWRfX3UCwfnCzWTZi rKjwqGAc0stNW4TdP2vNeP4UkxgvQRSupWpfVBd3hyxkz4qJ2YaMzw3nSPDLjwuCvZv7vgxQ7mV 8mQlDzYsc8ORT8YKuc8b7r9GLy1CM7D9Wvc0EysqRlODVmoN5EK16MtlkUyTGEqIjpLkpJh67Sk em+J962dBkMwP8TKLt0prbH3fy5f8JGPLahY4Zoq3D+O/yOgTvmExfvOcRmWCtOHUdJxDY2J+xG JOrZP5nWZcwQMkln0n4Ju0y5zuX2tj6hsnFf3Yx1pjhaee+fKq7yDZIqA/ypGSCHY7md+g7LPAj igs8ojC1/gC2aTwFIP8/O+P9oKHbbnumUzo09N0YNTz1Gi9nqMZkUuS6B1mRNdfzE1x27bNGluI 6NMjpivO8iO9iG9fRdXkN0I8MCeP9FYlRDlrFjn+Dsq76lfIeW9RN6BdrHYujCRk2i9kYetpFB5 IkFDQNzQXTY2ytcWx3w== X-Proofpoint-ORIG-GUID: _-yHB9lMN7gXjGxtowL3fBOnPRDBeKVR X-Authority-Analysis: v=2.4 cv=cOzQdFeN c=1 sm=1 tr=0 ts=6a1da577 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=p5SjDoQbJD9XZwj20uYA:9 X-Proofpoint-GUID: _-yHB9lMN7gXjGxtowL3fBOnPRDBeKVR X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-01_04,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 spamscore=0 bulkscore=0 malwarescore=0 phishscore=0 suspectscore=0 priorityscore=1501 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606010151 Fix the fault-in code so that it does not return success if a concurrent unmap event invalidated the fault-in process between the best-effort lockless check and the proper check with lock. The new behaviour is to retry, like the best-effort lockless check already did. This prevents the fault-in handler from returning success without having actually faulted in the requested page. Fixes: e907ae530133 ("KVM: s390: Add helper functions for fault handling") Signed-off-by: Claudio Imbrenda Reviewed-by: Steffen Eiden --- arch/s390/kvm/faultin.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/s390/kvm/faultin.c b/arch/s390/kvm/faultin.c index ddf0ca71f374..cf542b0a7e8e 100644 --- a/arch/s390/kvm/faultin.c +++ b/arch/s390/kvm/faultin.c @@ -36,7 +36,8 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa struct kvm_s390_mmu_cache *mc = NULL; struct kvm_memory_slot *slot; unsigned long inv_seq; - int foll, rc = 0; + int rc = -EAGAIN; + int foll; foll = f->write_attempt ? FOLL_WRITE : 0; foll |= f->attempt_pfault ? FOLL_NOWAIT : 0; @@ -53,7 +54,7 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa return 0; } - while (1) { + while (rc == -EAGAIN) { f->valid = false; inv_seq = kvm->mmu_invalidate_seq; /* Pairs with the smp_wmb() in kvm_mmu_invalidate_end(). */ @@ -110,20 +111,19 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa if (!mmu_invalidate_retry_gfn(kvm, inv_seq, f->gfn)) { f->valid = true; rc = gmap_link(mc, kvm->arch.gmap, f, slot); - kvm_release_faultin_page(kvm, f->page, !!rc, f->write_attempt); - f->page = NULL; } + kvm_release_faultin_page(kvm, f->page, !!rc, f->write_attempt); } - kvm_release_faultin_page(kvm, f->page, true, false); if (rc == -ENOMEM) { rc = kvm_s390_mmu_cache_topup(mc); if (rc) return rc; - } else if (rc != -EAGAIN) { - return rc; + rc = -EAGAIN; } } + + return rc; } int kvm_s390_get_guest_page(struct kvm *kvm, struct guest_fault *f, gfn_t gfn, bool w) -- 2.54.0