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Thu, 21 May 2026 13:05:34 +0000 (GMT) Received: from p-imbrenda.aag-de.ibm.com (unknown [9.52.223.175]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 21 May 2026 13:05:34 +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, pbonzini@redhat.com, seanjc@google.com, yan.y.zhao@intel.com, isaku.yamahata@intel.com Subject: [PATCH v2 1/5] KVM: s390: Track page size in struct guest_fault Date: Thu, 21 May 2026 15:05:29 +0200 Message-ID: <20260521130533.156491-2-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260521130533.156491-1-imbrenda@linux.ibm.com> References: <20260521130533.156491-1-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-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=ffCdDUQF c=1 sm=1 tr=0 ts=6a0f0325 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=HydwJh4hHmF5zmZ3e14A:9 X-Proofpoint-ORIG-GUID: DZbXDkbKjzRpQ523im5tC0gtKz2IWN3X X-Proofpoint-GUID: _ZircIAaRkx5g0A3L7Za8Z5zgqe8p6ol X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIxMDEyNiBTYWx0ZWRfX8UGLrXnVvLcv GrhvzhanDZVg4882rN2YpBzGHCx0K2OSFGoSTfzO/wGSlQYqJvBkzink4ksOaFs1TIfqY1WxweE zDY9xKVqu+gXjtuhvxuXcUZHotfFpzrGMf42hgpFJX13StCzmOByyQdbRR5CNDDx3A8omSYok+H CCTyjOgaz9L8PAZY1T1FRut1QbUL6NdkBjkjktkj2TmhyYie8MxTmq9oCFOtSFr/GnWo8nDELOh IMOutZe/hLTwQbKOTKMn0gfLsuH3fLxsa7FNazEbj/qvge4wmb3P2oJhalYUbKPnMAoqOFuauRg 4rLL2jUVnn6Zt3CD47g215hbD/t+vqDAEBfqKgWE43g7AOePsBtRY1KhZSCImtWK7bpWahmPaBF zs1quP+fuPzY+1D9bNLtQeOqa/qGKwnnxFXlvE2Fcu3XxEA/M95L+gkGEhBYJ1CHtqe1EkMkhZ3 pFJYtqVL6kQHUgIwJBg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-21_02,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605210126 Until now, the members of struct guest_fault are always accessed while holding the required locks, and thus the ptep and crstep pointers can be dereferenced safely. There will be some new cases where callers of kvm_s390_faultin_gfn() need to know the size of the page used to solve the fault, at which point no locks are held anymore, and dereferencing the crstep field is not possible. Introduce a new crste_region3 flag for struct guest_fault to indicate whether the crstep used to solve the fault was a region 3 entry with FC=1 (large pud). This allows to disambiguate all three possible scenarios: * If ptep is not NULL, the fault was solved with a pte. * If ptep is NULL and crste_region3 is 0, a segment entry with FC=1 (large pmd) was used. * If ptep is NULL and crste_region3 is 1, a region 3 entry with FC=1 (large pud) was used. Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/dat.h | 1 + arch/s390/kvm/gmap.c | 2 ++ 2 files changed, 3 insertions(+) diff --git a/arch/s390/kvm/dat.h b/arch/s390/kvm/dat.h index 8f8278c44879..db09b8fc34d6 100644 --- a/arch/s390/kvm/dat.h +++ b/arch/s390/kvm/dat.h @@ -500,6 +500,7 @@ struct guest_fault { bool write_attempt; /* Write access attempted */ bool attempt_pfault; /* Attempt a pfault first */ bool valid; /* This entry contains valid data */ + bool crste_region3; /* Whether crstep referst to a region3 entry */ void (*callback)(struct guest_fault *f); void *priv; }; diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c index 3c26e35af0ef..6f4143092871 100644 --- a/arch/s390/kvm/gmap.c +++ b/arch/s390/kvm/gmap.c @@ -545,6 +545,7 @@ static int gmap_handle_minor_crste_fault(struct gmap *gmap, struct guest_fault * newcrste.s.fc1.d = 1; newcrste.s.fc1.sd = 1; } + f->crste_region3 = is_pud(newcrste); /* In case of races, let the slow path deal with it. */ return !gmap_crstep_xchg_atomic(gmap, f->crstep, oldcrste, newcrste, f->gfn); } @@ -690,6 +691,7 @@ static int _gmap_link(struct kvm_s390_mmu_cache *mc, struct gmap *gmap, int leve if (oldval.val != _CRSTE_EMPTY(oldval.h.tt).val && crste_origin_large(oldval) != crste_origin_large(newval)) return -EAGAIN; + f->crste_region3 = is_pud(newval); } while (!gmap_crstep_xchg_atomic(gmap, f->crstep, oldval, newval, f->gfn)); if (f->callback) f->callback(f); -- 2.54.0