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Fri, 4 Sep 2026 06:06:49 +0000 (GMT) From: Claudio Imbrenda To: pbonzini@redhat.com Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, borntraeger@de.ibm.com Subject: [GIT PULL v1 03/11] KVM: s390: Fix _gaccess_shadow_fault() Date: Fri, 4 Sep 2026 08:06:39 +0200 Message-ID: <20260904060647.562443-4-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904060647.562443-1-imbrenda@linux.ibm.com> References: <20260904060647.562443-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=bc1bluPB c=1 sm=1 tr=0 ts=6a9a6001 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=E-UwkBRaFZ51XR-txJMA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTA0MDA1NCBTYWx0ZWRfX1XdT45zRx7bH y5mbjNRmoqFpZG/5qe7r/eQGUsYaaGNFHvnXZkv/WNb6j+7XJSQFVKhB0mF6sRTLCAwZRexvhcr Rr8tU5+Och0jyejRwZH8UfSUhsVA1ZU= X-Proofpoint-ORIG-GUID: FxYJf6AgzXS6CnR1I62kxMJV_qOgiamL X-Proofpoint-GUID: FxYJf6AgzXS6CnR1I62kxMJV_qOgiamL X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTA0MDA1NCBTYWx0ZWRfX6L54B772VT2b 0nPI2nA+AfiRetiNhoyMtBU2ngB4UDRd2wkomio07YGR1PZ/F+psIuUuaolUYMFIAab88yC/OMV kFw7UPFg8YYpt//BDyiKDaRo7RqYmmk/360tFYt99mF86rDeVy60DJ6185c+xDr3z/4ChIabAYF BqKbHRYiWlD3FhAlSx1Z9J9jkRL8rMoJuuBQgpYh74K+AhcaHZBRlr15btg7eSIxeGx1+UWXfJI TcYX9zjx1nY86DrPwWfir30sqkcj6ltlYjs7BAHdIdK4OFF4E+xDO2jmATDcSqrdzERESGhHon7 aIuBQKOk7sp61/I6WkomPdExMssrcH7FAdFWkmW6AFmi4tIoSHHXv14pZmFd0bZY8/3DLsnp5lu OHq78xtC70J8OlICjJm41Lv0LCqaKH2OANLPlueYZxHp/SQhy5zqETbGJ4dpcjhUj/cMz7Lbnpg 4AhHqSD1k4jjGmHCYJQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-04_02,2026-09-03_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 suspectscore=0 adultscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 phishscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609040054 In some circumstances, it is possible that the page of nested guest memory that is being shadowed is not present at all in the parent guest gmap. dat_entry_walk() will not find any leaf entry and return with -ENOENT, which will erroneously be propagated all the way to userspace. Fix by manually calling gmap_link() on the memory of the nested guest that is being shadowed if the mapping was not already present. Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") Signed-off-by: Claudio Imbrenda Message-ID: <20260828115439.145885-4-imbrenda@linux.ibm.com> --- arch/s390/kvm/s390/gaccess.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/s390/kvm/s390/gaccess.c b/arch/s390/kvm/s390/gaccess.c index e5c064f263df..405345ccc4f1 100644 --- a/arch/s390/kvm/s390/gaccess.c +++ b/arch/s390/kvm/s390/gaccess.c @@ -1589,12 +1589,25 @@ static inline int ___gaccess_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg parent = READ_ONCE(sg->parent); if (!parent) return -EAGAIN; +retry: scoped_guard(spinlock, &parent->children_lock) { if (READ_ONCE(sg->parent) != parent) return -EAGAIN; sg->invalidated = false; rc = _gaccess_do_shadow(vcpu->arch.mc, sg, saddr, walk); } + if (rc == -ENOENT) { + struct kvm_memory_slot *slot; + struct guest_fault *entries; + + entries = get_entries(walk); + slot = kvm_vcpu_gfn_to_memslot(vcpu, entries[LEVEL_MEM].gfn); + if (!slot) + return PGM_ADDRESSING; + rc = gmap_link(vcpu->arch.mc, parent, entries + LEVEL_MEM, slot); + if (!rc) + goto retry; + } if (!rc) kvm_s390_release_faultin_array(vcpu->kvm, walk->raw_entries, false); return rc; -- 2.55.0