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Wed, 12 Aug 2026 10:44:38 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 12 Aug 2026 10:44:38 +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 v2 9/9] KVM: s390: Fix _gaccess_shadow_fault() Date: Wed, 12 Aug 2026 12:44:36 +0200 Message-ID: <20260812104436.109741-10-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260812104436.109741-1-imbrenda@linux.ibm.com> References: <20260812104436.109741-1-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-Spam-Details-Enc: AW1haW4tMjYwODEyMDA4NCBTYWx0ZWRfXwLF4Fs0B74qH +LwV0hAFl6WUHsPpE5XubL2l2lKF772LnhWTAv6EzkVOr1Wq7tEkWaSB4a7823hNDqTZ+xtzpCu IahJwsaVZF0fpGY36ab1pk/Gulr1TAqaFl2T4CdcS5r3N8OpfVU06IVZ5XRRx04115BRCizK1yp xDK6Lih5iTf3iLoNyamnyBcVtgbLWMXLdFfs06bbuNTTUM5bZc0uZn4Pd4iV3/Qxm0RjimVyvAN 53pqtf8b8+k8tbMafX2vUMAF+j4I4SGRKRx1RWlvh3xpntfblUC0yoF4DPo5WtJ0RYn15DN/Xfv c3Vrgh/KHPy0TftTdjhN65K61gFgYNZWHGghimBE6v2SD/Bym1bpdRbPn/bY32XutJEQvI7NZOU Xtg1WeuSzgcHclz36Eo7W3x4HCgq6vJU6cFklNMhJsC4MxFguoF+19h9RsUT3klTdamfg/y+VBV gpLihxOzZcCzPXfAy/Q== X-Proofpoint-Spam-Info: AW1haW4tMjYwODEyMDA4NCBTYWx0ZWRfX4Mb6TM+VHRae 9zgutF0KeSd9uHhHS1csPEkJpMPJYug6JwZNa/qJJe0tOhjAH2qWfAOlmLVhUXDgYWRpMT/QM92 0dus1kn2xbZpjGp9on+AP1Ot/yvfKN0= X-Authority-Analysis: v=2.4 cv=RqD16imK c=1 sm=1 tr=0 ts=6a7c4e9c cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=E-UwkBRaFZ51XR-txJMA:9 X-Proofpoint-GUID: n3pp338sCFzIjwFHl1bibhBnoMV71W_N X-Proofpoint-ORIG-GUID: n3pp338sCFzIjwFHl1bibhBnoMV71W_N 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=2026-08-12_03,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 priorityscore=1501 suspectscore=0 lowpriorityscore=0 clxscore=1015 adultscore=0 bulkscore=0 malwarescore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608120084 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