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Tue, 11 Aug 2026 15:56:44 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 11 Aug 2026 15:56:44 +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 Subject: [PATCH v1 11/11] KVM: s390: Fix _gaccess_shadow_fault() Date: Tue, 11 Aug 2026 17:56:41 +0200 Message-ID: <20260811155641.219777-12-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260811155641.219777-1-imbrenda@linux.ibm.com> References: <20260811155641.219777-1-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-Proofpoint-GUID: 4AkJh6iew5EKkNn2tTyDpBB0ddY-sGFG X-Authority-Analysis: v=2.4 cv=PbDPQChd c=1 sm=1 tr=0 ts=6a7b4643 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=E-UwkBRaFZ51XR-txJMA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODExMDEzMCBTYWx0ZWRfXykcDdVOY8z2U 1kAWxK/xlBsTEjw2mUfPohUMyUrqW1zPyRCo8pveO/7Oo2buQ1ktTVOg/tEbk/p/i/oHLA22ZZH f529Gz+uXFnCBFl7FY8Z80zxyjXSf/0gIylZ4d7I3XYe5SiIepuOmJlo84ZKNRUkYsBzCmTUn7j BjsaK5goh9ZEsQw8Ly5ZpilREe2Nndy+UdANJ23Hs8OwowB3vJcucqn+CMAecW6SbcXqGWZLRvm 61Ewkmk8PUzU/qsEGXCn46VU+ZCkO8kDERIDPfLZWMJdvFcpONkuakmz0ychBKOfuLb7yf+3uIU fkXcCv+wwkRXW5w5RhMAfcl26EzprdcLdrMtcOAAeqgdzHi4bWXSOLJ86Lpl+K8no/3sMayLwbb URjGX9HPYks2/pbsDVMqRHYsnCl4odv142Spb7uf34HSiPAE0SD/VK7ODLCwg7zjS2yqsYZ2Cqa oq2ttKdbyua0Cwcoxqg== X-Proofpoint-ORIG-GUID: 4AkJh6iew5EKkNn2tTyDpBB0ddY-sGFG X-Proofpoint-Spam-Info: AW1haW4tMjYwODExMDEzMCBTYWx0ZWRfX7kQ9CzAwJFE3 f8T1+UtdKdKWKZyfmYdZLLDcEytRq+TC6GLtg1/erL9yC14Bk4XTrF6AuihIYzAvYBA0pl9Fq6h YHDg0osESg1/O/Al+o+wVJb/cC4Ghlk= 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=2026-08-11_03,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 bulkscore=0 impostorscore=0 malwarescore=0 adultscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 phishscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608110130 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 --- arch/s390/kvm/gaccess.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index 36102b2727fb..f3a889988cdb 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -1507,6 +1507,7 @@ static int _do_shadow_crste(struct kvm_s390_mmu_cache *mc, struct gmap *sg, gpa_ static int _gaccess_do_shadow(struct kvm_s390_mmu_cache *mc, struct gmap *sg, unsigned long saddr, struct pgtwalk *w) { + struct kvm_memory_slot *slot; struct guest_fault *entries; int flags, i, hl, gl, l, rc; union crste *table, *host; @@ -1551,8 +1552,17 @@ static int _gaccess_do_shadow(struct kvm_s390_mmu_cache *mc, struct gmap *sg, return -EAGAIN; } +retry: rc = dat_entry_walk(NULL, entries[LEVEL_MEM].gfn, sg->parent->asce, DAT_WALK_LEAF, TABLE_TYPE_PAGE_TABLE, &host, &ptep_h); + if (rc == -ENOENT) { + slot = gfn_to_memslot(sg->kvm, entries[LEVEL_MEM].gfn); + if (!slot) + return PGM_ADDRESSING; + rc = gmap_link(mc, sg->parent, entries + LEVEL_MEM, slot); + if (!rc) + goto retry; + } if (rc) return rc; -- 2.55.0