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Thu, 16 Jul 2026 14:14:36 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 16 Jul 2026 14:14:36 +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 0/4] s390: Reintroduce support for DCACHE_WORD_ACCESS Date: Thu, 16 Jul 2026 16:14:32 +0200 Message-ID: <20260716141436.2125703-1-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: kvm@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-Info: AW1haW4tMjYwNzE2MDE0NiBTYWx0ZWRfX5p6vGFNito04 CzyUZ9buJKdVqdacC1zaeRBctFjat9LS4lbH4TA21B/CKzIGN9ZyXwYzw28rvOxlUL7ntxocMKO 2xhDD4sqIFfX5D2tIY0X8/jYCDAq10g= X-Authority-Analysis: v=2.4 cv=Mp1iLWae c=1 sm=1 tr=0 ts=6a58e751 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=s88hA1X5yvA2iI4I3ysA:9 X-Proofpoint-GUID: TEIPo7He5tazw0HlIdL3ammqhHIsLvtc X-Proofpoint-ORIG-GUID: TEIPo7He5tazw0HlIdL3ammqhHIsLvtc X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE2MDE0NiBTYWx0ZWRfXxxdejVX4Ekv/ dvSVmUFPmpYt6HtaFN72/LQ3PZS43wZZCen/+EvpD3PYvmjL3CD0lf/Tgr2s9uLeJ7nanG8ylIC zx2LLHl0eWAFDt1i8rEoGjy7NkQrSIsU1OuXnIGR0laAh4tOsqBNtkzsPueqQ9i+0WH1HMeSODn nu2woGuUKJTCnnsQCUUN6bUyp+6YKXY/+Ao64e4p4Sps5PRU12h+g1gvUVH4cGnX4xR2+1ZmFHB XmT3LXYQy6htc4uT8BGLGaLJlRwAf+ARWLEVbpyhthX0/MO9cLq0urt2m6J8+Xd0/GP40hlqBH9 xX1rYoc3xKrEZfqRk0rIYDr9X/wnVHSt16VjJS88dR7T9KR+NXshsVGS6D5Ne9yXjgr/Pe3jnaP uUXIB7iGvD+6ylosaSBMmkW12JM1107TTyBiH330/rQskW3msN/GD0C/p6klXRAaR4IznAZr+d6 GYgV8I/miF+6/OB99kg== 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=2026-07-16_05,2026-07-15_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 bulkscore=0 spamscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 priorityscore=1501 suspectscore=0 clxscore=1011 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607160146 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 | 59 ++++++++++++++++++++++++++ arch/s390/kvm/pv.c | 6 +-- arch/s390/mm/extable.c | 18 ++++++++ arch/s390/mm/fault.c | 10 ++--- 8 files changed, 112 insertions(+), 10 deletions(-) -- 2.53.0