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Mon, 20 Jul 2026 22:55:53 +0000 (GMT) Received: from [9.61.240.94] (unknown [9.61.240.94]) by smtpav02.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 20 Jul 2026 22:55:53 +0000 (GMT) Message-ID: <9eb92918-ec25-4918-a89e-7209ba9d783b@linux.ibm.com> Date: Mon, 20 Jul 2026 18:55:53 -0400 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: Jaehoon Kim , borntraeger@linux.ibm.com, 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, mjrosato@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> Content-Language: en-US From: Douglas Freimuth In-Reply-To: <20260720222238.1576-1-jhkim@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: UXyQmO4lfZ0YwaKQgdPAawC4FQQNbDbK X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIwMDI0NiBTYWx0ZWRfX46y4gH8uY1jU lR+7zaT21/NHobn2kxJXKxXHk37eO/LhuarwbMzAO6Ti/3oTWCpKA4IknXvT7kIAgwOWzLx2Dpo W1xo9KuhRpSV8F6Wju6jwWrZko6gY05bVLfaoQzKHrCTLNRC/ckJhd/Din6mSaWCpwZZ8bqfNX4 3Kmv250viRsvg6+1tcsKXAs2ISU57AOg/ZpTXAZl20pfd74rxZiuQiC6mUZBExZrpidzNy6RWAx tugRfzqvJ4q0AjifYihmtRPI5IczfFJ3aTDElpq/6PgCqF/oJ2EqBM0oq4BfRidFXq+W3yBR+2M AVzvij00eXUgrlzDBylNB9WiRyKK3499h8rDcTXctfPpWy1eVbNSPg+SVSiZEJQ1G52dlyTz6Wd GxpyNiJgenj2qV2PDxtxlBAy3zZMj30k3Qzhs8iDJOwxhPPT6AveiBnItF1f907uKGOLsk4JhDe oRFuprEzkeDayYGHubQ== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIwMDI0NiBTYWx0ZWRfXxxMT0OF5iT4O JE1l9UtCWvWqiuGnCQSVDwkCMem7vvYuMrN4xTCkumzHEHT6YxoTA0cGdu/a+7s5yLiS+DI/s5Y fnU4umPyHSLjXGlMel6TO/wAICpjxCU= X-Proofpoint-GUID: UXyQmO4lfZ0YwaKQgdPAawC4FQQNbDbK X-Authority-Analysis: v=2.4 cv=SM5ykuvH c=1 sm=1 tr=0 ts=6a5ea77c cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=ccGYm0h6Pc7MciaZ97sA:9 a=QEXdDO2ut3YA:10 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=2026-07-20_05,2026-07-20_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 bulkscore=0 suspectscore=0 adultscore=0 spamscore=0 malwarescore=0 priorityscore=1501 phishscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607200246 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; > } > spin_lock_irqsave(&adapter->maps_lock, flags); > if (adapter->nr_maps < MAX_S390_ADAPTER_MAPS) { Reviewed-by: Douglas Freimuth