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Wed, 19 Nov 2025 11:06:12 +0000 (GMT) Date: Wed, 19 Nov 2025 12:06:09 +0100 From: Claudio Imbrenda To: Heiko Carstens Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, nsg@linux.ibm.com, nrb@linux.ibm.com, seiden@linux.ibm.com, schlameuss@linux.ibm.com, svens@linux.ibm.com, agordeev@linux.ibm.com, gor@linux.ibm.com, david@redhat.com, gerald.schaefer@linux.ibm.com Subject: Re: [PATCH v3 15/23] KVM: s390: Add helper functions for fault handling Message-ID: <20251119120609.4a4bf008@p-imbrenda> In-Reply-To: <20251118151005.9674Af1-hca@linux.ibm.com> References: <20251106161117.350395-1-imbrenda@linux.ibm.com> <20251106161117.350395-16-imbrenda@linux.ibm.com> <20251118151005.9674Af1-hca@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: PCZXa7uLXtCC8Dgv-qApYf4PvvbyofZT X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTE1MDAzMiBTYWx0ZWRfXxmj9TFKMiS4F ktazYnXCQlNcjDjmGRyGjqAi5+DrXiuD7Zf0BUvheAaa1vLfh9WLWPD9LIx3HyNxw5cLtsybWcC AmvBRQ+nyEs+Pt+OHnwUVMVubf6onF/vipNpIyhEJ9JQQrqsmQiD7rToCMUK99HONfYmyuyUFU6 B5ASyXfRlM0p772z5WvfQn+y00gIW7yKsEbeTSjJVSLoIDj7wjCtukKBZlg/qmA0hBjqdtOReEa sP2KZhCyiMAnJRXSrbF6tN19Uv0Kae1sgB0Gk6+JCF3QcQx0FaKqCxQl2rzIRBQ8kYh3LEtTPtJ Qwsy1A8rRG4MWlxYwtHYSJ67uWK00SIraxrJVmoAXSh3tznMbHs1CeQDoWn9RuW/3SFGFLU75xr uZpu45xAM5cxfyr9zfB2hO9/rMoHyQ== X-Proofpoint-ORIG-GUID: PCZXa7uLXtCC8Dgv-qApYf4PvvbyofZT X-Authority-Analysis: v=2.4 cv=XtL3+FF9 c=1 sm=1 tr=0 ts=691da4ac cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=W69JXFrg6a1OFCXWetkA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-19_03,2025-11-18_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 bulkscore=0 priorityscore=1501 impostorscore=0 adultscore=0 lowpriorityscore=0 phishscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511150032 On Tue, 18 Nov 2025 16:10:05 +0100 Heiko Carstens wrote: > On Thu, Nov 06, 2025 at 05:11:09PM +0100, Claudio Imbrenda wrote: > > Add some helper functions for handling multiple guest faults at the > > same time. > > > > This will be needed for VSIE, where a nested guest access also needs to > > access all the page tables that map it. > > > > Signed-off-by: Claudio Imbrenda > > --- > > arch/s390/include/asm/kvm_host.h | 1 + > > arch/s390/kvm/Makefile | 2 +- > > arch/s390/kvm/faultin.c | 148 +++++++++++++++++++++++++++++++ > > arch/s390/kvm/faultin.h | 92 +++++++++++++++++++ > > arch/s390/kvm/kvm-s390.c | 2 +- > > arch/s390/kvm/kvm-s390.h | 2 + > > 6 files changed, 245 insertions(+), 2 deletions(-) > > create mode 100644 arch/s390/kvm/faultin.c > > create mode 100644 arch/s390/kvm/faultin.h > > ... > > > +int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fault *f) > > +{ > > ... > > > + scoped_guard(read_lock, &kvm->mmu_lock) { > > + if (!mmu_invalidate_retry_gfn(kvm, inv_seq, f->gfn)) { > > + f->valid = true; > > + rc = gmap_link(mc, kvm->arch.gmap, f); > > + kvm_release_faultin_page(kvm, f->page, !!rc, f->write_attempt); > > + f->page = NULL; > > + } > > + } > > + kvm_release_faultin_page(kvm, f->page, true, false); > > + > > + if (rc == -ENOMEM) { > > + rc = kvm_s390_mmu_cache_topup(mc); > > If I'm not mistaken then gmap_link() -> dat_link() maps the possible -ENOMEM > return value of dat_entry() to -EAGAIN. So the case where -ENOMEM leads to a > kvm_s390_mmu_cache_topup() call will never happen. oops, you're right I'll fix dat_link() accordingly