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 5470D2416BC; Wed, 15 Jan 2025 13:23:23 +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=1736947404; cv=none; b=p9OAhthuGorwFeBqID7i7SvpP7jpyh/sAN/tWI2yzNUJLrtU4GNgZHszR+wLWsJK1yFrZbWLIPtfSVHE8b+ZFGZz+tm9V/dVvTQ4493ANyzVP0ZG+LfEke4mnounMcHGsw3gjUAS6eNjU5s9Thn/0ucLNakFXrFL0qQ4KosaCZc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736947404; c=relaxed/simple; bh=8rEyapAs4bN3/7JypysB0w817tkTZaKZAkueBuDIj/E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=k3dFlCasl5seG8uCzMYL9v6jccWlKOjsb2oX50oxjk+6VlexB9fXKEri4Hjiv5pAIqlMhyGkxs52rjijJEmRH4j9Y1/QFwe4Mv4rOQa+ctRmfnZTNUyuSXWVG+7LXAG9a+StLYUh7s1tcjw3TcwwjsNaXz/NvTHz9ZH6fetx3Wc= 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=sQvMJ5jT; 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="sQvMJ5jT" Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 50F3rDA0019833; Wed, 15 Jan 2025 13:23:19 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=4PE0Bn aXjAeUeZpx9Bhgn8IXerIFbsOOJOTUfLoUOwc=; b=sQvMJ5jTZR5DDs+OqXskUh 46C+xD05pPBu5WG4utXW6QEU8N5CS4ULbbT/aHqXyWolZk/pVewDH9304bWSWaZz Yh7NM2aG2vON12GtT5c77WndOjnf/uox7p+x4PcxvPwBwtFvDXc4UhdiuOrlurZH AHH+lyk/IjkjoA1ktZbGbzrGq1P4uRj8CEUpgy//PaHvkEh3aXrulk9+NpT0a/OO n/G75l9CHVtHeaFFTR0sJXJAy2XaCwR5PVYTPOuq3EaH7tj0zIeXSt2KdqWMyfR4 OGikoJPq775wJxa020HfQURxYiPR72CeHTePn9cGH8EtsGl9URPMXBK464tyHfTw == 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 4465gjt98m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Jan 2025 13:23:19 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 50FBJChP017400; Wed, 15 Jan 2025 13:23:17 GMT Received: from smtprelay01.fra02v.mail.ibm.com ([9.218.2.227]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4444fk8cc5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Jan 2025 13:23:17 +0000 Received: from smtpav06.fra02v.mail.ibm.com (smtpav06.fra02v.mail.ibm.com [10.20.54.105]) by smtprelay01.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 50FDNElv31326548 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 15 Jan 2025 13:23:14 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 134AB2004B; Wed, 15 Jan 2025 13:23:14 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 76F4320040; Wed, 15 Jan 2025 13:23:13 +0000 (GMT) Received: from [9.171.76.32] (unknown [9.171.76.32]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 15 Jan 2025 13:23:13 +0000 (GMT) Message-ID: <10d919b5-1b38-476c-8a60-96cd805dcef7@linux.ibm.com> Date: Wed, 15 Jan 2025 14:23:13 +0100 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 04/13] KVM: s390: move pv gmap functions into kvm To: Claudio Imbrenda Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, schlameuss@linux.ibm.com, david@redhat.com, willy@infradead.org, hca@linux.ibm.com, svens@linux.ibm.com, agordeev@linux.ibm.com, gor@linux.ibm.com, nrb@linux.ibm.com, nsg@linux.ibm.com References: <20250108181451.74383-1-imbrenda@linux.ibm.com> <20250108181451.74383-5-imbrenda@linux.ibm.com> <03d91fa8-6f3f-4052-9b03-de28e88f0001@linux.ibm.com> <20250115135919.57fac908@p-imbrenda> Content-Language: en-US From: Janosch Frank Autocrypt: addr=frankja@linux.ibm.com; keydata= xsFNBFubpD4BEADX0uhkRhkj2AVn7kI4IuPY3A8xKat0ihuPDXbynUC77mNox7yvK3X5QBO6 qLqYr+qrG3buymJJRD9xkp4mqgasHdB5WR9MhXWKH08EvtvAMkEJLnqxgbqf8td3pCQ2cEpv 15mH49iKSmlTcJ+PvJpGZcq/jE42u9/0YFHhozm8GfQdb9SOI/wBSsOqcXcLTUeAvbdqSBZe zuMRBivJQQI1esD9HuADmxdE7c4AeMlap9MvxvUtWk4ZJ/1Z3swMVCGzZb2Xg/9jZpLsyQzb lDbbTlEeyBACeED7DYLZI3d0SFKeJZ1SUyMmSOcr9zeSh4S4h4w8xgDDGmeDVygBQZa1HaoL Esb8Y4avOYIgYDhgkCh0nol7XQ5i/yKLtnNThubAcxNyryw1xSstnKlxPRoxtqTsxMAiSekk 0m3WJwvwd1s878HrQNK0orWd8BzzlSswzjNfQYLF466JOjHPWFOok9pzRs+ucrs6MUwDJj0S cITWU9Rxb04XyigY4XmZ8dywaxwi2ZVTEg+MD+sPmRrTw+5F+sU83cUstuymF3w1GmyofgsU Z+/ldjToHnq21MNa1wx0lCEipCCyE/8K9B9bg9pUwy5lfx7yORP3JuAUfCYb8DVSHWBPHKNj HTOLb2g2UT65AjZEQE95U2AY9iYm5usMqaWD39pAHfhC09/7NQARAQABzSVKYW5vc2NoIEZy YW5rIDxmcmFua2phQGxpbnV4LmlibS5jb20+wsF3BBMBCAAhBQJbm6Q+AhsjBQsJCAcCBhUI CQoLAgQWAgMBAh4BAheAAAoJEONU5rjiOLn4p9gQALjkdj5euJVI2nNT3/IAxAhQSmRhPEt0 AmnCYnuTcHRWPujNr5kqgtyER9+EMQ0ZkX44JU2q7OWxTdSNSAN/5Z7qmOR9JySvDOf4d3mS bMB5zxL9d8SbnSs1uW96H9ZBTlTQnmLfsiM9TetAjSrR8nUmjGhe2YUhJLR1v1LguME+YseT eXnLzIzqqpu311/eYiiIGcmaOjPCE+vFjcXL5oLnGUE73qSYiujwhfPCCUK0850o1fUAYq5p CNBCoKT4OddZR+0itKc/cT6NwEDwdokeg0+rAhxb4Rv5oFO70lziBplEjOxu3dqgIKbHbjza EXTb+mr7VI9O4tTdqrwJo2q9zLqqOfDBi7NDvZFLzaCewhbdEpDYVu6/WxprAY94hY3F4trT rQMHJKQENtF6ZTQc9fcT5I3gAmP+OEvDE5hcTALpWm6Z6SzxO7gEYCnF+qGXqp8sJVrweMub UscyLqHoqdZC2UG4LQ1OJ97nzDpIRe0g6oJ9ZIYHKmfw5jjwH6rASTld5MFWajWdNsqK15k/ RZnHAGICKVIBOBsq26m4EsBlfCdt3b/6emuBjUXR1pyjHMz2awWzCq6/6OWs5eANZ0sdosNq dq2v0ULYTazJz2rlCXV89qRa7ukkNwdBSZNEwsD4eEMicj1LSrqWDZMAALw50L4jxaMD7lPL jJbazsFNBFubpD4BEADAcUTRqXF/aY53OSH7IwIK9lFKxIm0IoFkOEh7LMfp7FGzaP7ANrZd cIzhZi38xyOkcaFY+npGEWvko7rlIAn0JpBO4x3hfhmhBD/WSY8LQIFQNNjEm3vzrMo7b9Jb JAqQxfbURY3Dql3GUzeWTG9uaJ00u+EEPlY8zcVShDltIl5PLih20e8xgTnNzx5c110lQSu0 iZv2lAE6DM+2bJQTsMSYiwKlwTuv9LI9Chnoo6+tsN55NqyMxYqJgElk3VzlTXSr3+rtSCwf tq2cinETbzxc1XuhIX6pu/aCGnNfuEkM34b7G1D6CPzDMqokNFbyoO6DQ1+fW6c5gctXg/lZ 602iEl4C4rgcr3+EpfoPUWzKeM8JXv5Kpq4YDxhvbitr8Dm8gr38+UKFZKlWLlwhQ56r/zAU v6LIsm11GmFs2/cmgD1bqBTNHHcTWwWtRTLgmnqJbVisMJuYJt4KNPqphTWsPY8SEtbufIlY HXOJ2lqUzOReTrie2u0qcSvGAbSfec9apTFl2Xko/ddqPcZMpKhBiXmY8tJzSPk3+G4tqur4 6TYAm5ouitJsgAR61Cu7s+PNuq/pTLDhK+6/Njmc94NGBcRA4qTuysEGE79vYWP2oIAU4Fv6 gqaWHZ4MEI2XTqH8wiwzPdCQPYsSE0fXWiYu7ObeErT6iLSTZGx4rQARAQABwsFfBBgBCAAJ BQJbm6Q+AhsMAAoJEONU5rjiOLn4DDEP/RuyckW65SZcPG4cMfNgWxZF8rVjeVl/9PBfy01K 8R0hajU40bWtXSMiby7j0/dMjz99jN6L+AJHJvrLz4qYRzn2Ys843W+RfXj62Zde4YNBE5SL jJweRCbMWKaJLj6499fctxTyeb9+AMLQS4yRSwHuAZLmAb5AyCW1gBcTWZb8ON5BmWnRqeGm IgC1EvCnHy++aBnHTn0m+zV89BhTLTUal35tcjUFwluBY39R2ux/HNlBO1GY3Z+WYXhBvq7q katThLjaQSmnOrMhzqYmdShP1leFTVbzXUUIYv/GbynO/YrL2gaQpaP1bEUEi8lUAfXJbEWG dnHFkciryi092E8/9j89DJg4mmZqOau7TtUxjRMlBcIliXkzSLUk+QvD4LK1kWievJse4mte FBdkWHfP4BH/+8DxapRcG1UAheSnSRQ5LiO50annOB7oXF+vgKIaie2TBfZxQNGAs3RQ+bga DchCqFm5adiSP5+OT4NjkKUeGpBe/aRyQSle/RropTgCi85pje/juYEn2P9UAgkfBJrOHvQ9 Z+2Sva8FRd61NJLkCJ4LFumRn9wQlX2icFbi8UDV3do0hXJRRYTWCxrHscMhkrFWLhYiPF4i phX7UNdOWBQ90qpHyAxHmDazdo27gEjfvsgYMdveKknEOTEb5phwxWgg7BcIDoJf9UMC In-Reply-To: <20250115135919.57fac908@p-imbrenda> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: BA3XMNUnlPQpa4MddkHHcwGrQBTIXc2F X-Proofpoint-GUID: BA3XMNUnlPQpa4MddkHHcwGrQBTIXc2F X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-01-15_05,2025-01-15_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 clxscore=1015 suspectscore=0 lowpriorityscore=0 malwarescore=0 spamscore=0 priorityscore=1501 mlxlogscore=910 impostorscore=0 adultscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501150099 On 1/15/25 1:59 PM, Claudio Imbrenda wrote: > On Wed, 15 Jan 2025 13:48:47 +0100 > Janosch Frank wrote: > > [...] > >>> +static int __gmap_make_secure(struct gmap *gmap, struct page *page, void *uvcb) >>> +{ >>> + struct folio *folio = page_folio(page); >>> + int rc; >>> + >>> + /* >>> + * Secure pages cannot be huge and userspace should not combine both. >>> + * In case userspace does it anyway this will result in an -EFAULT for >>> + * the unpack. The guest is thus never reaching secure mode. If >>> + * userspace is playing dirty tricky with mapping huge pages later >> >> s/tricky/tricks/ >> >> But the whole last sentence is a bit iffy. > > hmm yes I'll reword it > >> >>> + * on this will result in a segmentation fault or in a -EFAULT return >>> + * code from the KVM_RUN ioctl. >>> + */ >>> + if (folio_test_hugetlb(folio)) >>> + return -EFAULT; >>> + if (folio_test_large(folio)) { >>> + mmap_read_unlock(gmap->mm); >>> + rc = uv_wiggle_folio(folio, true); >>> + mmap_read_lock(gmap->mm); >> >> You could move the unlock to uv_wiggle_folio() and add a >> mmap_assert_locked() in front. > > oh no, I don't want a function that drops a lock that has been acquired > outside of it. > > by explicitly dropping and acquiring it, it's obvious what's going on, > and you can easily see that the lock is being dropped and re-acquired. > > __gmap_destroy_page() does it, but it's called exactly in one spot, > namely gmap_destroy_page(), which is literally below it. > It's just very weird to to me to have the (un)lock dance the wrong way around when reading it. At first I assumed you made a mistake when remembering the context description in wiggle because I misread the unlock() as lock(). But maybe that's just me and I don't mind it too much :)