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Fri, 17 Jul 2026 09:24:15 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 17 Jul 2026 09:24:15 +0000 (GMT) From: Heiko Carstens To: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , David Hildenbrand Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 0/4] s390: Reintroduce support for DCACHE_WORD_ACCESS Date: Fri, 17 Jul 2026 11:24:11 +0200 Message-ID: <20260717092415.3039699-1-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 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: 3WtQ_0wCtl0ckVQqCpxV3F_bcnV3YvLv X-Proofpoint-Spam-Info: AW1haW4tMjYwNzE3MDA5MSBTYWx0ZWRfX89UYidydxB+E mVhWFsk1D0/kmQBGKILaPYoAK7yMTwtgLZXEo3gELmiZ6+yLo8tynon5Xig8Ys9ucTnZ89kouAC 3qdtfsBa44CJ6p4UaAZgna3nkn++dT0= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE3MDA5MSBTYWx0ZWRfXyfEGV57gKemC MJfmzx/NqATuEo1xZAspfDC8eWUxggY3CYpJOQWBXLHC5wO8ithS1GmTnWoWlo+QbTmV/ysTGcs TtSIofmbWFB9TYu+qt1y2toSxW3ZngD6GZq8G0plBuAaUo/s+jKz1g5VyP14DYrpSZASQjHObV7 bQ3HQ5fHMRe3rq5sqRqfpvN+0Qv/8O38kf2rlcewSTZ3L4Csat5oBe7SvU2KVcUM/71tIWRDerJ kUfwYe9x2P+H1AkxwONzLPmSA9v53teZ5fMgiCkNfNj86NnxTrzod3I+qUeo1ccCTjuMdTFPGNb +pe9BnET1vg1Ela2i6meS9mHMR6YnztWDQtzS6QAeKe+MnMT52T6n3uDsN6vd/139qCxPlM8iZu gmcUHhAVcYCibB8QUJCbOXA9b72IyoCHZDsT+Z/61ZKBSy7wpjotM6pNFj76VLRXUC7VZW5g7NO bwwjQ5Ss3S0QgVEqfMA== X-Authority-Analysis: v=2.4 cv=XbS5Co55 c=1 sm=1 tr=0 ts=6a59f4c5 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=01MaQ8ttZPKmpqd4eLYA:9 X-Proofpoint-ORIG-GUID: 3WtQ_0wCtl0ckVQqCpxV3F_bcnV3YvLv X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-17_02,2026-07-15_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 suspectscore=0 spamscore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 adultscore=0 malwarescore=0 impostorscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607170091 v2: - Explicitely PAGE_ALIGN size in uv_alloc_stor_var() [Sashiko] - Document that lazy PTE update / TLB flushing is intended [Sashiko] v1: Support for DCACHE_WORD_ACCESS was recently removed [1] since it caused problems with the incomplete handling of secure storage access exceptions. It looked like fixing the exception handler would be a larger effort; therefore support for DCACHE_WORD_ACCESS was removed as a work around. Address the potential problems that exist with secure storage access exceptions and add support for DCACHE_WORD_ACCESS again. In particular address the following problems: - Reading the guest variable storage area via the /proc/kcore interface results in short reads. Address this by using a VM_SPARSE area for the guest variable storage area. VM_SPARSE areas will be handled like memory holes (zeros will be read). - Fix handling of secure storage access exceptions in vmalloc area. - Remove folio handling for secure storage access exceptions to avoid potential data corruption. [1] 37540b8c287f ("s390: Revert support for DCACHE_WORD_ACCESS") Heiko Carstens (4): KVM: s390: pv: Use VM_SPARSE area for guest variable storage area s390/mm: Fix handling of secure storage access exceptions in vmalloc area s390/mm: Remove folio handling for secure storage access exceptions s390: Add support for DCACHE_WORD_ACCESS (again) arch/s390/Kconfig | 1 + arch/s390/include/asm/asm-extable.h | 4 ++ arch/s390/include/asm/uv.h | 2 + arch/s390/include/asm/word-at-a-time.h | 22 +++++++++ arch/s390/kernel/uv.c | 65 ++++++++++++++++++++++++++ arch/s390/kvm/pv.c | 6 +-- arch/s390/mm/extable.c | 18 +++++++ arch/s390/mm/fault.c | 10 ++-- 8 files changed, 118 insertions(+), 10 deletions(-) -- 2.53.0