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Fri, 12 Sep 2025 17:56:03 +0000 (GMT) Message-ID: <92285479bc2b97b418b0efe8a52f0711a95cbf36.camel@linux.ibm.com> Subject: Re: [PATCH v2 05/20] KVM: s390: Add helper functions for fault handling From: Nina Schoetterl-Glausch To: Claudio Imbrenda , kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, nrb@linux.ibm.com, seiden@linux.ibm.com, schlameuss@linux.ibm.com, hca@linux.ibm.com, svens@linux.ibm.com, agordeev@linux.ibm.com, david@redhat.com, gerald.schaefer@linux.ibm.com Date: Fri, 12 Sep 2025 19:56:02 +0200 In-Reply-To: <20250910180746.125776-6-imbrenda@linux.ibm.com> References: <20250910180746.125776-1-imbrenda@linux.ibm.com> <20250910180746.125776-6-imbrenda@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTA2MDE5NSBTYWx0ZWRfX+mrilySnSLKG TSsRHMuhp3Ct/5MJLYdW1cZOCuJF9XFrXTalJWz0K3+Ij1nw0DVeujZ7tFzHx5yIOqRJG1rlYeZ lVbhpBjlB+too7dT2ftNL8Y3BclULEfiZvI31DaOMpI5m1/8fjCFbQvPYxnKWc/wEZjyYzLOQjq J65NxCX4ohNZSfBQGsgsJ+li6GKYmjDOM6qQnChmksVDqG09Md6CZqmJK4hCO6T3IPUdx7DX4pg DkTwWdT/meLLLOFDuIPyOMy5kJbM0+0i0eZ7vjnTyWoLVp/gmUjy1UQqVu/KJjwJF5KVtnYWPev CM9lqv3z2ckJxIoTeW9aQJUtgKZIJWkys9rGEvfC1ckYt9QrkHa8pSzagCcg4aHqY/eXhyDDK0+ 9C1x0IRm X-Proofpoint-ORIG-GUID: RkepuE5y3wT8jEHLKdA0jrtrVaWCVNHP X-Proofpoint-GUID: RkepuE5y3wT8jEHLKdA0jrtrVaWCVNHP X-Authority-Analysis: v=2.4 cv=StCQ6OO0 c=1 sm=1 tr=0 ts=68c45eb8 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=yJojWOMRYYMA:10 a=VnNF1IyMAAAA:8 a=YNtB7HBByXDDIQ3sV5sA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-12_06,2025-09-12_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 malwarescore=0 bulkscore=0 clxscore=1015 adultscore=0 suspectscore=0 priorityscore=1501 impostorscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509060195 On Wed, 2025-09-10 at 20:07 +0200, Claudio Imbrenda wrote: > Add some helper functions for handling multiple guest faults at the > same time. >=20 > This will be needed for VSIE, where a nested guest access also needs to > access all the page tables that map it. >=20 > Signed-off-by: Claudio Imbrenda > --- > arch/s390/kvm/gaccess.h | 14 ++++++++++ > arch/s390/kvm/kvm-s390.c | 44 +++++++++++++++++++++++++++++++ > arch/s390/kvm/kvm-s390.h | 56 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 114 insertions(+) >=20 [...] > diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h > index c44fe0c3a097..dabcf65f58ff 100644 > --- a/arch/s390/kvm/kvm-s390.h > +++ b/arch/s390/kvm/kvm-s390.h > @@ -22,6 +22,15 @@ >=20 [...] > +static inline void release_faultin_multiple(struct kvm *kvm, struct gues= t_fault *guest_faults, > + int n, bool ignore) > +{ > + int i; > + > + for (i =3D 0; i < n; i++) { > + kvm_release_faultin_page(kvm, guest_faults[i].page, ignore, > + guest_faults[i].write_attempt); > + guest_faults[i].page =3D NULL; > + } > +} > + > +static inline bool __kvm_s390_multiple_faults_need_retry(struct kvm *kvm= , unsigned long seq, > + struct guest_fault *guest_faults, int n, > + bool unsafe) The name of the function does not at all suggest that it releases guest pag= es. Can you remove that and use if (__kvm_s390_fault_array_needs_retry(...)) release_faultin_array(...); in the caller? (I haven't yet looked at those) "needs_retry" isn't telling me much right now, either. What is being retried and why? Comments would not hurt :) > +{ > + int i; > + > + for (i =3D 0; i < n; i++) { > + if (!guest_faults[i].valid) > + continue; > + if ((unsafe && mmu_invalidate_retry_gfn_unsafe(kvm, seq, guest_faults[= i].gfn)) || > + (!unsafe && mmu_invalidate_retry_gfn(kvm, seq, guest_faults[i].gfn= ))) { > + release_faultin_multiple(kvm, guest_faults, n, true); > + return true; > + } > + } > + return false; > +} > + > +static inline int __kvm_s390_faultin_gfn_range(struct kvm *kvm, struct g= uest_fault *guest_faults, > + gfn_t start, int n_pages, bool write_attempt) > +{ > + int i, rc =3D 0; > + > + for (i =3D 0; !rc && i < n_pages; i++) > + rc =3D __kvm_s390_faultin_gfn(kvm, guest_faults + i, start + i, write_= attempt); > + return rc; > +} > + > +#define release_faultin_array(kvm, array, ignore) \ > + release_faultin_multiple(kvm, array, ARRAY_SIZE(array), ignore) > + > +#define __kvm_s390_fault_array_needs_retry(kvm, seq, array, unsafe) \ > + __kvm_s390_multiple_faults_need_retry(kvm, seq, array, ARRAY_SIZE(array= ), unsafe) > + > /* implemented in diag.c */ > int kvm_s390_handle_diag(struct kvm_vcpu *vcpu); > =20 --=20 IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Wolfgang Wendt Gesch=C3=A4ftsf=C3=BChrung: David Faller Sitz der Gesellschaft: B=C3=B6blingen / Registergericht: Amtsgericht Stuttg= art, HRB 243294