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Wed, 4 Feb 2026 15:03:01 +0000 (GMT) From: Claudio Imbrenda To: kvm@vger.kernel.org Cc: 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, gra@linux.ibm.com, schlameuss@linux.ibm.com, hca@linux.ibm.com, svens@linux.ibm.com, agordeev@linux.ibm.com, gor@linux.ibm.com, david@kernel.org, gerald.schaefer@linux.ibm.com Subject: [PATCH v7 08/29] s390/mm: Warn if uv_convert_from_secure_pte() fails Date: Wed, 4 Feb 2026 16:02:37 +0100 Message-ID: <20260204150259.60425-9-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260204150259.60425-1-imbrenda@linux.ibm.com> References: <20260204150259.60425-1-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: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjA0MDExMyBTYWx0ZWRfXyBnAd7/AiFXG NqIZ8otL826+ELG1ypCe15/2ypbCO7027oPOJk8c8Xi5mMIyjtBlmCVMWxkOvSmSdmBfkW7ts8M aQtN0+REDPJH36pROLG8lAASouSrmAIWloAZQ9Spgh/iSHbMTfP5F7Wzc7BRiII7QsR7upBVa8a QeUrwgZxqaryhbnaoofZxj43Kp7OnDcUXKCjp0WUQFqBCUUkj18FmbrYTX7iotN0s3tkwyRH+GS pYECrw0UmdFgy9Ocq8a+3pwy1LS5xJjk9QA/X/3tz86zJ3+J7WimEXXj4f4+V8PTjRBCUT3Nitd KWzMKTGkP1rgJe8fAxf4mo6T8nun3NE39CZWScUcHtTE4qCP8NOSzluvQpD5y7+8MSz/DZ0aM6W nGZ9M1vGOJX0Obfo6ACdLspi/Pk5YayQ9+DjphqwWnYzp1NKNr6vJqM0N5qrmh9fi7ufdHM+wQJ 3UiKnNpYDpfy9S0dsOw== X-Proofpoint-GUID: OBo_1wYLNWGoA9Tb0Fh3liAmLAa0ft-n X-Proofpoint-ORIG-GUID: OBo_1wYLNWGoA9Tb0Fh3liAmLAa0ft-n X-Authority-Analysis: v=2.4 cv=LesxKzfi c=1 sm=1 tr=0 ts=69835fab cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=gEHK17p0qXyn9eJGjbgA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-04_04,2026-02-04_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 spamscore=0 lowpriorityscore=0 clxscore=1015 adultscore=0 suspectscore=0 priorityscore=1501 phishscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2601150000 definitions=main-2602040113 Content-Type: text/plain; charset="utf-8" If uv_convert_from_secure_pte() fails, the page becomes unusable by the host. The failure can only occour in case of hardware malfunction or a serious KVM bug. When the unusable page is reused, the system can have issues and hang. Print a warning to aid debugging such unlikely scenarios. Signed-off-by: Claudio Imbrenda --- arch/s390/include/asm/pgtable.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtabl= e.h index 73c30b811b98..04335f5e7f47 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1239,7 +1239,7 @@ static inline pte_t ptep_get_and_clear(struct mm_stru= ct *mm, res =3D ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID)); /* At this point the reference through the mapping is still present */ if (mm_is_protected(mm) && pte_present(res)) - uv_convert_from_secure_pte(res); + WARN_ON_ONCE(uv_convert_from_secure_pte(res)); return res; } =20 @@ -1257,7 +1257,7 @@ static inline pte_t ptep_clear_flush(struct vm_area_s= truct *vma, res =3D ptep_xchg_direct(vma->vm_mm, addr, ptep, __pte(_PAGE_INVALID)); /* At this point the reference through the mapping is still present */ if (mm_is_protected(vma->vm_mm) && pte_present(res)) - uv_convert_from_secure_pte(res); + WARN_ON_ONCE(uv_convert_from_secure_pte(res)); return res; } =20 @@ -1294,9 +1294,10 @@ static inline pte_t ptep_get_and_clear_full(struct m= m_struct *mm, /* * If something went wrong and the page could not be destroyed, or * if this is not a mm teardown, the slower export is used as - * fallback instead. + * fallback instead. If even that fails, print a warning and leak + * the page, to avoid crashing the whole system. */ - uv_convert_from_secure_pte(res); + WARN_ON_ONCE(uv_convert_from_secure_pte(res)); return res; } =20 --=20 2.52.0