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 107A020D50C; Fri, 16 May 2025 17:08:14 +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=1747415296; cv=none; b=ovagO1sw4lsHM3aLmN9AmXthyPnckY2U2+8xmut5UMO7iSL6WeTB2hjIiTWm00HEQcPp2LsWtXxuKq94+u4m+NULNhpSwFnL8CWwGJsRiDhi8da3NzThRGP0Ln6RBXKeYpjVpqJKz4o+QF0Bjq2m6EB//T0wTGIk1cK0QtDo3qA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747415296; c=relaxed/simple; bh=D4nh/p3rGy8bs/0DL+q9ngAuVpsmPitUfEbzGeaXiSk=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=QAlyo544Y9lwq9SVkgC96ekVgn1gU4of2QinVTsXzTJuFHW/++PzbPKb+4xhqNbWS6KxaAARpFBulVQf4BQcY/zbvg4Pi68w5FRDgF7FyEo4WCy/3ibwvJuQIwUYTmnPLLXdBQDKJYN3iO7w0VmtBHK/glMUdWrvkbWe0HQMylg= 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=sPO0BWrS; 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="sPO0BWrS" Received: from pps.filterd (m0353729.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 54GGeScU024369; Fri, 16 May 2025 17:08:03 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=l9XaRt t7nqTQopEcJ6psPRLnUWut+d/TtKq81TymnfM=; b=sPO0BWrSkY7Vlbv4ZLrqdw HmBl9M+mfcmxwy1NKC+fPUE/hosEomsXDOhHQztnPW1wisvOCfulpMPqrp4wVxd0 pFJCCGwVpcGPitc8NdrSzjk0w3nqf8x8gKcdbNp/+U9pZELq4seT0+mJrqqds9kT rncygBj+DJvIsK8BGbJcK42DTd0vIkKYooUt5NXYKJDk28tbFViWrL8EEDs5TDbN sTRXy9S47axe75SfqfHQ/XYtUlYy6at/joNYz8R1q77O9yKWqPPV3T/pR6TiEwSi JeXkiPZzkKw4kjkMLa6bO4pexF3EUyVL/4xrRHSdy98bCfKBel/b3CEsXDZny70g == Received: from ppma13.dal12v.mail.ibm.com (dd.9e.1632.ip4.static.sl-reverse.com [50.22.158.221]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 46nyytk4kc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 16 May 2025 17:08:03 +0000 (GMT) Received: from pps.filterd (ppma13.dal12v.mail.ibm.com [127.0.0.1]) by ppma13.dal12v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 54GEOitU019443; Fri, 16 May 2025 17:08:02 GMT Received: from smtprelay06.fra02v.mail.ibm.com ([9.218.2.230]) by ppma13.dal12v.mail.ibm.com (PPS) with ESMTPS id 46mbfs0mhj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 16 May 2025 17:08:02 +0000 Received: from smtpav06.fra02v.mail.ibm.com (smtpav06.fra02v.mail.ibm.com [10.20.54.105]) by smtprelay06.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 54GH7wah23134642 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 16 May 2025 17:07:58 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 32C16200CF; Fri, 16 May 2025 17:07:58 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B5642200CB; Fri, 16 May 2025 17:07:57 +0000 (GMT) Received: from p-imbrenda (unknown [9.152.224.66]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 16 May 2025 17:07:57 +0000 (GMT) Date: Fri, 16 May 2025 19:07:55 +0200 From: Claudio Imbrenda To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, Christian Borntraeger , Janosch Frank , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Thomas Huth , Matthew Wilcox , Zi Yan , Sebastian Mitterle Subject: Re: [PATCH v1 0/3] s390/uv: handle folios that cannot be split while dirty Message-ID: <20250516190755.32917d48@p-imbrenda> In-Reply-To: <20250516123946.1648026-1-david@redhat.com> References: <20250516123946.1648026-1-david@redhat.com> Organization: IBM X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: cbLRk8KAcORrniPp6oJAntkKow6roWiN X-Proofpoint-ORIG-GUID: cbLRk8KAcORrniPp6oJAntkKow6roWiN X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNTE2MDE2NyBTYWx0ZWRfX3xqHC4oBj9bo YZYdBu/Paw1MLiE/054CZBnb7aVupy8kUOokX55rXkThUKc6DqCIX4/qSbwmU0L3SIyOoqTROnQ mxKIoQA42qkEUh6VM8NAnLYSdSXq53cu7rjBRViArtPm63dcfWsZc8Tx3XthPQg4p2VD9E6LZ4j dhu/E8LF/TcOZRTlyhaRxAIDlhXnW50twx5/aDlB4oQIC5RZFA+3PUnZJHSgX02kb99IkQGwD/m 9prYMk4clzlIeJ4VAiWqRi9QcakrSqkBjC7eFIkIiTN9PvF66CcjyZEB0rEjAiHMR+MGrrqrBeM +amziRU8KT96wLkfFI1jGVw6w3URX5ag005MocrhZ1y79Hzov3qd7XFHwxqYs3td0W4IFlChVRY T/TR90EACXZGgdZ0HKeEUdSI1zYOzNZKlSFysdn2xTm7/GAOR1qFDHdYv/hkrFASGuCPAegZ X-Authority-Analysis: v=2.4 cv=ZcMdNtVA c=1 sm=1 tr=0 ts=682770f3 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=kj9zAlcOel0A:10 a=dt9VzEwgFbYA:10 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=JfrnYn6hAAAA:8 a=Ikd4Dj_1AAAA:8 a=bI5ggvasLi50PZegio4A:9 a=CjuIK1q_8ugA:10 a=1CNFftbPRP8L7MoqJWF3:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-05-16_05,2025-05-16_03,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 adultscore=0 spamscore=0 clxscore=1011 bulkscore=0 priorityscore=1501 mlxlogscore=744 impostorscore=0 mlxscore=0 phishscore=0 suspectscore=0 lowpriorityscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505070000 definitions=main-2505160167 On Fri, 16 May 2025 14:39:43 +0200 David Hildenbrand wrote: > From patch #3: > > " > Currently, starting a PV VM on an iomap-based filesystem with large > folio support, such as XFS, will not work. We'll be stuck in > unpack_one()->gmap_make_secure(), because we can't seem to make progress > splitting the large folio. > > The problem is that we require a writable PTE but a writable PTE under such > filesystems will imply a dirty folio. > > So whenever we have a writable PTE, we'll have a dirty folio, and dirty > iomap folios cannot currently get split, because > split_folio()->split_huge_page_to_list_to_order()->filemap_release_folio() > will fail in iomap_release_folio(). > > So we will not make any progress splitting such large folios. > " > > Let's fix one related problem during unpack first, to then handle such > folios by triggering writeback before immediately trying to split them > again. > > This makes it work on XFS with large folios again. > > Long-term, we should cleanly supporting splitting such folios even > without writeback, but that's a bit harder to implement and not a quick > fix. yet another layer of duck tape I really dislike the current interaction between secure execution and I/O, I hope I can get a cleaner solution as soon as possible meanwhile, let's keep the boat afloat; whole series: Reviewed-by: Claudio Imbrenda David: thanks for fixing this mess! > > Cc: Christian Borntraeger > Cc: Janosch Frank > Cc: Claudio Imbrenda > Cc: David Hildenbrand > Cc: Heiko Carstens > Cc: Vasily Gorbik > Cc: Alexander Gordeev > Cc: Sven Schnelle > Cc: Thomas Huth > Cc: Matthew Wilcox > Cc: Zi Yan > Cc: Sebastian Mitterle > > David Hildenbrand (3): > s390/uv: don't return 0 from make_hva_secure() if the operation was > not successful > s390/uv: always return 0 from s390_wiggle_split_folio() if successful > s390/uv: improve splitting of large folios that cannot be split while > dirty > > arch/s390/kernel/uv.c | 85 ++++++++++++++++++++++++++++++++++++------- > 1 file changed, 72 insertions(+), 13 deletions(-) > > > base-commit: 088d13246a4672bc03aec664675138e3f5bff68c