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 6690B357D05; Wed, 22 Jul 2026 17:07:41 +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=1784740063; cv=none; b=WPvf61sSTyQEiq+sA5yrnUvQqUZktiyRpiDvZ4Wy+oPEEm4USwss+waJPfo+BidHrNv+RXU8ZKRoTCcX/kF9FIjkOVnaG+Q+H7D8Dt/9wdNwvkT9w1d8mnzyt6I7Sn/g9PMbcBz2EVTxBCH+6imh82bGdcqGZaUfDKtrGXXA2vw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784740063; c=relaxed/simple; bh=RGcOPnSYLJ4mOJrYDgSzpmIPBpkS7L5XiBWEFg4u+uI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kvDH8WVlvDBiTaXdR7jaz5U868lJa35kAL+810LY5i/6HS4DIdqCXGOiVMLdDW9vR4wfw1QWvpoHtpu09ez4ExH1KVRsWjgOafpn0ra35o2jPF9sPpPbmWnSYZ4AhYQITEXJy+8o/TMQaV6mNG8B4Z0s+fauurFOAEAsDFHG5S0= 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=ObuIuTJf; 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="ObuIuTJf" Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 66MFfZoK382674; Wed, 22 Jul 2026 17:07:39 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=T9+QSJ F9EgXIyN+CEtxcSgBjFojG8nomL2QDWuuhZgw=; b=ObuIuTJfGKLsIi0HgqEtjX EUK2ID/jU1QSMaFhejUDk8oLt/+pU7g1qbotSvxx9L/3dirqMi17ZYOzAH+RbyQY Mk2Z79RRVoiOcD7aeIYBfuGkPzoIB6ac8BEt9Yt3ysSZxLoYavjT4XrQs4e2Q9A9 0PelnXHcX9akVyRWXKSeCkRFjRvoxB22zx9l/fLykr/Lh3Bo5FGm95KTr2xQf2gz BpwrnEj5OboAky0uBv9VPa2v8KtEfJn3/DxCVsmYa0zqhMaFWm6vnpZ8c4N0HMt5 jDhYa7cN4rT+r+zqTC5N50O90KBcFv7J1VZ64Pb9rQssW+OJDQD9Um8wT35DRiVQ == Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4fg7913d5j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 22 Jul 2026 17:07:39 +0000 (GMT) Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 66MH52bw023639; Wed, 22 Jul 2026 17:07:38 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4fgm6w8dfw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 22 Jul 2026 17:07:38 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 66MH7XMx34472334 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 22 Jul 2026 17:07:34 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D3B43200EF; Wed, 22 Jul 2026 17:07:33 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0D558200E9; Wed, 22 Jul 2026 17:07:33 +0000 (GMT) Received: from [9.87.159.222] (unknown [9.87.159.222]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 22 Jul 2026 17:07:32 +0000 (GMT) Message-ID: <2a080b3b-1a2f-489d-9d66-492e00c57f72@linux.ibm.com> Date: Wed, 22 Jul 2026 19:07:32 +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 v1] KVM: s390: Fall back to short-term pinning in MAP ioctl To: Matthew Rosato , Jaehoon Kim , frankja@linux.ibm.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com Cc: david@kernel.org, svens@linux.ibm.com, freimuth@linux.ibm.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260720222238.1576-1-jhkim@linux.ibm.com> <1f64ec8b-2e22-42c7-b823-74d2bc30f3aa@linux.ibm.com> Content-Language: en-US From: Christian Borntraeger In-Reply-To: <1f64ec8b-2e22-42c7-b823-74d2bc30f3aa@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: e7YFXAHHWg0xyFtufh7V8dV_SLrB-nQn X-Authority-Analysis: v=2.4 cv=V6RNF+ni c=1 sm=1 tr=0 ts=6a60f8db cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=Z92YMGwyAAsvk4tsDzUA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIyMDE2NCBTYWx0ZWRfX9gtJeBmyhAj1 qkchpSvPHE6acSwEksRFqCQdpZ6C6lO8i+FwjkVke7f8w260WhMiQiiJlLGR0eEz7bKqxUnmypw jq56tHJSaByuOnRdsNNPoRsZuRlpwKM= X-Proofpoint-GUID: e7YFXAHHWg0xyFtufh7V8dV_SLrB-nQn X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIyMDE2NCBTYWx0ZWRfX59GAfomS4c5B 5zMsfVdeGA58BX1TrwPKiUm3Z3TUVlRFCgKe489tkTVv1459PmLEd6HRypm3hNbfW0m6TjwfDQL lZRHkZTIQ4WufMFiH+Nu9rNWasNQCsbPklRbtWQnVvuZzT25Ahb2AdJcOhSxZksrrY1yGkG8MIi QvZEZ7e2ON+swtrtkF4SxbccBYR7rnbcr8r4c17gdeTNBnQ+1lvd1IvOgWlLfnUVJc8B0lO8L6+ lHq1hMHC5XbX6NS3BQYlfCcNV52sGfcGQuzaYLAT/we42SXiV1uT/7o8/4/GFkIuOQWWDaIRmdd 7hbsEgkSz9huS7wtMFU7cFNHr3u69s1l/4FtfldGnpepzoB3gZWm3XNNYuNgP+rHicsJHUfHdnn L3oIxdcbrKuxfMd3O9V0cK9RfZsP81CsJpxMBuiBwolMBiM4HKXnBAY0j0ejX9EF6a3SNflB4JB Dr6oCBm1+VxJ+ZmV4PQ== 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=2026-07-22_04,2026-07-22_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 adultscore=0 bulkscore=0 lowpriorityscore=0 clxscore=1015 spamscore=0 impostorscore=0 phishscore=0 priorityscore=1501 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607220164 Am 22.07.26 um 17:51 schrieb Matthew Rosato: > On 7/20/26 6:22 PM, Jaehoon Kim wrote: >> FOLL_LONGTERM pinning fails for some memory types, such as file-backed >> guest memory. As a result, kvm_s390_adapter_map() returns -EINVAL and >> irqfd adapter registration fails even though interrupt delivery could >> still work via the existing non-atomic path. >> >> When FOLL_LONGTERM pinning fails, verify that the page is accessible >> using a short-term pin instead. If the short-term pin succeeds, >> immediately unpin the page and return success. The non-atomic irqfd >> path already performs short-term pinning for interrupt delivery, so >> this restores the previous behavior for memory that cannot be pinned >> long-term. >> >> Fixes: adcd5b3e758b ("KVM: s390: Add map/unmap ioctl and clean mappings post-guest") >> Signed-off-by: Jaehoon Kim >> --- >> arch/s390/kvm/interrupt.c | 15 +++++++++++++-- >> 1 file changed, 13 insertions(+), 2 deletions(-) >> >> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c >> index 9e3e6b0d72ad..4b68e0cb51f6 100644 >> --- a/arch/s390/kvm/interrupt.c >> +++ b/arch/s390/kvm/interrupt.c >> @@ -2520,8 +2520,19 @@ static int kvm_s390_adapter_map(struct kvm *kvm, unsigned int id, __u64 addr) >> map->addr = host_addr; >> map->page = pin_map_page(kvm, host_addr, FOLL_LONGTERM); >> if (!map->page) { >> - ret = -EINVAL; >> - goto out; >> + /* >> + * Long-term pinning may fail for memory types such as file-backed >> + * memory. Check whether short-term pinning is possible so that the >> + * non-atomic irqfd path can handle interrupt injection. >> + */ >> + map->page = pin_map_page(kvm, host_addr, 0); >> + if (!map->page) { >> + ret = -EINVAL; >> + goto out; >> + } >> + unpin_user_page(map->page); >> + kfree(map); >> + return 0; > > This makes sense, but what happens later on the kvm_s390_adapter_unmap? > > Won't we return -ENOENT because nothing was in the list? > > Is it worth detecting/recognizing this case? I could think of 2 ways... > > 1) re-doing the above test during unmap > > 2) stashing an entry in adapter->maps but with a new flag that indicates > it was approved for short-term pinning only (e.g. return NULL > immediately if a match is found during get_map_info() with this flag > set), and during kvm_s390_adapter_unmap() and > kvm_s390_unmap_all_adapters() just remove it from the list without doing > any unpin/page dirtying. > > #2 might be a little more code but sounds cleaner? > When we are at it, can we also fix Documentation/virt/kvm/devices/s390_flic.rst ? To me it looks like qemu does not check the error for unmapping, but yes, maybe 2 is the right thing to do.