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Thu, 6 Nov 2025 15:25:46 +0000 (GMT) From: Claudio Imbrenda To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, mhartmay@linux.ibm.com, nrb@linux.ibm.com, nsg@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, ggala@linux.ibm.com, david@redhat.com Subject: [PATCH v1 1/1] KVM: s390: Fix gmap_helper_zap_one_page() again Date: Thu, 6 Nov 2025 16:25:45 +0100 Message-ID: <20251106152545.338188-1-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.51.1 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-Authority-Analysis: v=2.4 cv=StmdKfO0 c=1 sm=1 tr=0 ts=690cbdff cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=hc2NwQUhtlEWUF91VgoA:9 X-Proofpoint-ORIG-GUID: PPbXzuvdWZmfUfVvDHg_xbUhVffvJ9Qq X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTAxMDAxOCBTYWx0ZWRfX/ouv/e8mabm4 +nrjP7XCRoqBndZr4vqYW21w/zxq9maqd+c8/AXH1LbDl54gZ8jhgXUH2VPEg2hqbQmzob9V1Ji /kLqiIPRuzBh0b01VOEZ+mtgXPANFMdxLcuvZDYXT2DH9NfweC1xlHBqW433cNsIKlhrTbe4rnG ohneebLB2xTKSVRu3NOqE52NV0X3/+tmAahiPkcYBvj2ltQZDLzTLoXLOE8a8w5xl+MnJuQFOiD G9RLxg6UHtMEpehMYLbvdg9WenE33k637fQ1FlFpmKYLxi+at1amleYts1CxJeTj957wpymFrt3 Zl+oJx3tz4EbfqlkGgnGi1aa1tXgbUMUTFQjTxXz01bfVRa7WzKoFhEdfSxTceYn7a1DOcST0C+ TsMhe3UHHHmJJyxqXm+RZxEklzV1GQ== X-Proofpoint-GUID: PPbXzuvdWZmfUfVvDHg_xbUhVffvJ9Qq X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-06_03,2025-11-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 phishscore=0 impostorscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 adultscore=0 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511010018 A few checks were missing in gmap_helper_zap_one_page(), which can lead to memory corruption in the guest under specific circumstances. Add the missing checks. Fixes: 5deafa27d9ae ("KVM: s390: Fix to clear PTE when discarding a swapped page") Reported-by: Marc Hartmayer Signed-off-by: Claudio Imbrenda --- arch/s390/mm/gmap_helpers.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/s390/mm/gmap_helpers.c b/arch/s390/mm/gmap_helpers.c index d4c3c36855e2..38a2d82cd88a 100644 --- a/arch/s390/mm/gmap_helpers.c +++ b/arch/s390/mm/gmap_helpers.c @@ -47,6 +47,7 @@ static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry) void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) { struct vm_area_struct *vma; + unsigned long pgstev; spinlock_t *ptl; pgste_t pgste; pte_t *ptep; @@ -65,9 +66,13 @@ void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) if (pte_swap(*ptep)) { preempt_disable(); pgste = pgste_get_lock(ptep); + pgstev = pgste_val(pgste); - ptep_zap_swap_entry(mm, pte_to_swp_entry(*ptep)); - pte_clear(mm, vmaddr, ptep); + if ((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED || + (pgstev & _PGSTE_GPS_ZERO)) { + ptep_zap_swap_entry(mm, pte_to_swp_entry(*ptep)); + pte_clear(mm, vmaddr, ptep); + } pgste_set_unlock(ptep, pgste); preempt_enable(); -- 2.51.1