From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 756E633C518; Fri, 17 Jul 2026 09:05:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784279122; cv=none; b=kiK+S38F6mugA1o9rUSDdw/XKUetltgqxVw9EZ7S5w272cjiDYvUgEY8nFjHcsQujnb0ou2YO/FfdhqtecwzGoHPY29OYF1TmoIoFedLPxBHiix8iKIGENxwmtOFxBSQ5d1Fedp/XxgxBbA8aU4s/VRTmsv9jkAcEgglnFg28uo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784279122; c=relaxed/simple; bh=duervrsXsempBqbm0OWKWBcN2NT84vcay8Uab08FJ0k=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=s5A1TErCluxK9OIPPuLmBYzIviNu5pQg+TKzzwIfuqm+AfvxWeoADQ/cpmlYcYWx640VGlX6OZ3kqouneV9a/jTbw3H4n30dWFjv3f8+jlEwPV6QsfPrue6Q7VfcWjc6Sh6a5a11D7mOXXuY7KOmxrF6Rois0Hm9bjr79cyxnaU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=ASyniwHo; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="ASyniwHo" Received: from pps.filterd (m0353729.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 66H6fbBu3602047; Fri, 17 Jul 2026 09:05:18 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=j1mCeF 4U+u244jn5iAkFoGO6ncb6yfVP0T4Ela+HT98=; b=ASyniwHocK+TBhRmwZ8x1+ Niu6sWO2LYN4oSvppeT+Ir1w/l8zRbOPnD7hzjo2qaq6eHcDUMjctaUL4riOVqmW 209oG6LBYhQ0a3Qb28zGYCfvRIw2jwvmkLyo/8t6eWmbewD7/svYlPLJsmYoa0dj 9nih0JXIjwlKr1/+PJgWaWVUvgAgPRtS9pA/1RLm44faUKpHZxMFl+NwiBBRkgy4 hRxqHHEBNjiSue7yhXzyfTjOnbaocPLHXWmR9c1QPjdrYPcRw2/jCEpfSMi6AO3m qgB/mn8oQP+Wv1jmnn5bC4yeoc1o4oA2Wj35upDTtkSehT7+5hDFGKBsQngcGOsg == Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4fcv33p6a0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 17 Jul 2026 09:05:17 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 66H94cKP026520; Fri, 17 Jul 2026 09:05:16 GMT Received: from smtprelay02.fra02v.mail.ibm.com ([9.218.2.226]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4fc1nhrvy7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 17 Jul 2026 09:05:16 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay02.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 66H95CoY52494592 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 17 Jul 2026 09:05:12 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9898120043; Fri, 17 Jul 2026 09:05:12 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 557B720040; Fri, 17 Jul 2026 09:05:12 +0000 (GMT) Received: from [9.224.77.173] (unknown [9.224.77.173]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 17 Jul 2026 09:05:12 +0000 (GMT) Message-ID: <1e04d9c8-ea80-4b19-8f56-9d622261964a@linux.ibm.com> Date: Fri, 17 Jul 2026 11:05:12 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/4] s390: Reintroduce support for DCACHE_WORD_ACCESS To: Heiko Carstens , Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Janosch Frank , Claudio Imbrenda , David Hildenbrand Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260716141436.2125703-1-hca@linux.ibm.com> Content-Language: en-US From: Christian Borntraeger In-Reply-To: <20260716141436.2125703-1-hca@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzE3MDA4NiBTYWx0ZWRfX3+sT3RiDj2b7 +6P4bQNYxEIacAjcT3gqETtLKim65IJxGKCTx6A6JrnCm9bgMKJFeVozpuPjFvGUPNYDHdTPY/a xY1ajAOlB0gI7F9D6s9qJu/a14wydYM= X-Authority-Analysis: v=2.4 cv=Mp1iLWae c=1 sm=1 tr=0 ts=6a59f04e cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=yUqyZBMAralKIz-t7gkA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: EIbV_yYe33i9iNS7qZQjXH9_wsZdEmCY X-Proofpoint-ORIG-GUID: EIbV_yYe33i9iNS7qZQjXH9_wsZdEmCY X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE3MDA4NiBTYWx0ZWRfX/Z1c6Llf73pq Gv/rE+9Nkg6Sv4CL+diZ043ntjsfthZ+2z5FE2YpR70vT2iXhPPLsIEY/S7dELAPh1xiRco7KB+ cPVUVG/md27oRP+lXRc615durnAQ/AOA8XAMJFsowbVrwgSQWyW2Cu69/rm8nUVQGWXjjIXhmcT Z8uVLfYLtfgdKN0AFS8TCw7kvUTHQBpx+LeRKYX7WZdYvxqHSYlkhE9T8ZmK7/3Ij+vBZOC492g swM2bOZhWGE90UVhTbFbEkJccLJvkl68M8ZkHZ8pI+b4mYmsjNz+IYoRA83yzlADc+6ogLpxLWs b/+nhY0jiGEWnyVS/jJOKE7AvW9WsJ3DRH+JaYw6GYRFXlKdWNpUyPwZ+XnYhehtOedKaPeSEd+ JJl/qtH9gFJw9Lq36ourzkTjuYtv8/5H/rVFgC4hFm8E25UYyVa5ZCrdXatlsopuui4kP2r6rWu iXqUPIdiQ8MGZp8tsiw== 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 adultscore=0 bulkscore=0 spamscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 priorityscore=1501 suspectscore=0 clxscore=1015 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607170086 Am 16.07.26 um 16:14 schrieb Heiko Carstens: > 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) Whole series Tested-by: Christian Borntraeger with a kernel module and a hacked up kselftest. > > 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(-) >