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Mon, 24 Aug 2026 19:26:50 +0000 (GMT) Received: from [9.61.96.163] (unknown [9.61.96.163]) by smtpav02.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 24 Aug 2026 19:26:49 +0000 (GMT) Message-ID: <88a04bb8-76f1-4805-af42-558e6499f841@linux.ibm.com> Date: Mon, 24 Aug 2026 15:26:49 -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 1/4] s390/vfio-ap: Fix leak of pinned NIB and registered NISC in vfio_ap_irq_enable() To: Matthew Rosato , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: jjherne@linux.ibm.com, borntraeger@de.ibm.com, pasic@linux.ibm.com, alex@shazbot.org, kwankhede@nvidia.com, fiuczy@linux.ibm.com, pbonzini@redhat.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, agordeev@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, stable@vger.kernel.org References: <20260824135850.503728-1-akrowiak@linux.ibm.com> <20260824135850.503728-2-akrowiak@linux.ibm.com> Content-Language: en-US From: Anthony Krowiak In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI0MDE2MSBTYWx0ZWRfXxZEqJk3+u1i/ Fbs/vw7K5rv/KClxOrt64hDA7BAhO87KSEKmp9EvuR2DXHkRKz1gK6IQipM9yLRO4ZHfOC0JP9q y+D6PKO0uGspEuQvbjJ3XpEsqE3TgJ8= X-Authority-Analysis: v=2.4 cv=AYuB2XXG c=1 sm=1 tr=0 ts=6a8c9afe cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=oJhS4qge3_J52AN1xGYA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: ufc8smyBS976Xa_pMSkZPHGHY9vJpJO7 X-Proofpoint-GUID: ufc8smyBS976Xa_pMSkZPHGHY9vJpJO7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI0MDE2MSBTYWx0ZWRfXzbzp3f2oU08s k2hF+00LG8b5+TMy1UGq1vf9K08ZdMXFlQRkzk97SpiVP5PlSqkwkIXa5DsojoTyPL1y6n2Y1VD 3P23BeMj7TLFm1/vXrDxkm9fANjAf40a/CvbI0cM/bmWo0YvwWMCEjE35Hkr4lNT1bfx+jq/22r Qd7GHf36uecCBRJVKfUqNeptYFYvEqalHM8zqKg22Y1HYeHCJ9xmKuAKXa1II5ixhoap8Az/o3X fVNrrCu1bNY/c0XYBUoNXVdzqb81wjOxSywf9P4W6cbtK9Qw8FYFOChOPqJJBtoXRMAWGE20Q+M dPe/+arExFbAA0ZzO3wd8xWV54IN7Ddtuir4WHy29Yo7YYCn8vTfTOLwjIJdzNMhZlAz2DPWA4L LpFuZ2WtLZw2Tkp86fMrZCa3raMp2Nu0uAOEqwiBk1BlW2bXiZOkGNb1bLNELyhZp6P4WLrdtR5 TQd+rzOmOZPP5pMjOEg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-24_05,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 phishscore=0 clxscore=1015 adultscore=0 bulkscore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608240161 On 8/24/26 12:57 PM, Matthew Rosato wrote: > On 8/24/26 9:58 AM, Anthony Krowiak wrote: >> The vfio_ap_irq_enable() function executes the PQAP(AQIC) instruction to >> enable interrupts for an AP queue. A switch statement is used to examine >> the status response code returned from the instruction to determine >> whether it succeeded or failed and react accordingly. For the default case, >> the vfio_ap_irq_disable function is invoked to disable interrupts for the >> queue and clean up the AQIC resources (i.e., unpin the NIB and unregister >> the NISC). There are a number of problems with this: >> >> 1. Neither the q->saved_iova nor q->saved_isc has been set, so the >> AQIC resources - assuming those values have been previously set - will >> be the NIB and NISC resources from a prior call; the NIB and NISC from >> the current call are therefore leaked. >> >> 2. Interrupts may never have been enabled. Sending a disable instruction to >> a queue that the hardware just told you is in a bad state (CHECKSTOPPED, >> DECONFIGURED, Q_NOT_AVAIL) is at best wasted work and at worst generates >> a further WARN_ONCE from inside vfio_ap_irq_disable's own default. >> >> 3. The hardware just rejected the new ap_aqic() enable attempt with an >> unexpected status. Disabling a previously-working IRQ config - assuming >> that is even possible - as a reaction to a failed enable attempt does >> not make sense; it is actively destructive, tearing down something that >> was working for no valid reason. >> >> The fix is to unregister the NISC and an unpin the NIB in the default case >> of the switch statement. >> >> Fixes: ec89b55e3bce7 ("s390: ap: implement PAPQ AQIC interception in kernel") >> Cc: stable@vger.kernel.org >> Signed-off-by: Anthony Krowiak >> --- >> drivers/s390/crypto/vfio_ap_ops.c | 11 ++++++++--- >> 1 file changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c >> index 940c0ff668be..a46bf381ab72 100644 >> --- a/drivers/s390/crypto/vfio_ap_ops.c >> +++ b/drivers/s390/crypto/vfio_ap_ops.c >> @@ -503,9 +503,14 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q, >> vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1); >> break; >> default: >> - pr_warn("%s: apqn %04x: response: %02x\n", __func__, q->apqn, >> - status.response_code); >> - vfio_ap_irq_disable(q); >> + pr_warn("%s: PQAP(AQIC) failed with response code %02x for apqn %04x\n", >> + __func__, status.response_code, q->apqn); > LGTM, except Sashiko mentions the pr_warn here that you are updating has > a pre-existing issue. > > Since you're touching it already, do you think it makes sense to switch > to pr_warn_ratelimited with this patch? I think it makes more sense to switch to VFIO_AP_DBF_WARN which all other guest-triggered warning paths in  this function already use. > >> + /* We could not modify IRQ settings: clear new configuration */ >> + ret = kvm_s390_gisc_unregister(kvm, isc); >> + if (ret) >> + VFIO_AP_DBF_WARN("%s: kvm_s390_gisc_unregister: rc=%d isc=%d, apqn=%#04x\n", >> + __func__, ret, isc, q->apqn); >> + vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1); >> break; >> } >>