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Thu, 28 May 2026 14:08:31 +0000 (GMT) Received: from osiris (unknown [9.52.216.133]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTPS; Thu, 28 May 2026 14:08:31 +0000 (GMT) Date: Thu, 28 May 2026 16:08:29 +0200 From: Steffen Eiden To: Claudio Imbrenda Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@kernel.org, nrb@linux.ibm.com, schlameuss@linux.ibm.com, gra@linux.ibm.com Subject: Re: [PATCH v1 4/7] KVM: s390: Fix fault-in code Message-ID: <20260528140829.405668-G-seiden@linux.ibm.com> References: <20260528114727.142178-1-imbrenda@linux.ibm.com> <20260528114727.142178-5-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260528114727.142178-5-imbrenda@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=L4MtheT8 c=1 sm=1 tr=0 ts=6a184c64 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=kj9zAlcOel0A:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=yyblsrMLF2mYRii7pEUA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-ORIG-GUID: cgXa2Gm0giiomvmSrANLPc1-uYIynKO4 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTI4MDE0MyBTYWx0ZWRfX0x79a0QaoxN7 D2PYAZnGsixvh8f/pWt64s8p6z7rnftHmnkDpqXShfwwiUbWUK0QE27TNVs/E4szwQ2XllGzhAk rMZFUXiDnrx6nNN0di8PdaqDdrJ06ca1BsvcvojchzX6HMnELLPuYt4eRXG0NMCJd9a0K9Ia/tF y+zoN9inoLjmGI2uCZl0cFaNst38usyZd4rTHL5nCahanO0cl8a7E27pJF0bwVrDeyXEtWX71Pb qMMgd8xFj6OWDtRT5znwsDGK9wni2fJHO9LabuvKq6AhamCklwkcdT24WuXIovtmRFfx4M3jocd IBTWoSxIt5qc82Pira7sVUBZQvtodrruOposQVgf/eN+6Q+GLPTcaD8daB3hLbbEhEi95pHnU5h vrJHtCDOJS1OQwZugDSWpm3Fk3Zo7HnRd9WtK4oWLcdjQtwvR6hrQen1zR0zI3jA5P6b65g+7bF GsqjFZN8U+VeChxrC/g== X-Proofpoint-GUID: cgXa2Gm0giiomvmSrANLPc1-uYIynKO4 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=2026-05-28_03,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 malwarescore=0 bulkscore=0 impostorscore=0 adultscore=0 priorityscore=1501 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2605280143 On Thu, May 28, 2026 at 01:47:24PM +0200, Claudio Imbrenda wrote: > 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. > One nit below. Reviewed-by: Steffen Eiden > Fixes: e907ae530133 ("KVM: s390: Add helper functions for fault handling") > Signed-off-by: Claudio Imbrenda > --- > arch/s390/kvm/faultin.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/arch/s390/kvm/faultin.c b/arch/s390/kvm/faultin.c > index ddf0ca71f374..3047dfdc8be4 100644 > --- a/arch/s390/kvm/faultin.c > +++ b/arch/s390/kvm/faultin.c > @@ -36,7 +36,7 @@ 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 foll, rc = -EAGAIN; This is not in reverse Christmas tree anymore. Split them into two lines. ... Steffen