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Thu, 16 Jan 2025 16:46:02 +0000 (GMT) Message-ID: Date: Thu, 16 Jan 2025 11:46:02 -0500 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] s390/vfio-ap: Signal eventfd when guest AP configuration is changed To: freude@linux.ibm.com, Rorie Reyes Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, hca@linux.ibm.com, borntraeger@de.ibm.com, agordeev@linux.ibm.com, gor@linux.ibm.com, pasic@linux.ibm.com, jjherne@linux.ibm.com, alex.williamson@redhat.com References: <20250107183645.90082-1-rreyes@linux.ibm.com> <45d553cd050334029a6d768dc6639433@linux.ibm.com> Content-Language: en-US From: Anthony Krowiak In-Reply-To: <45d553cd050334029a6d768dc6639433@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Ok5TMgexn1KyPpBewFrZ9VpDM0f2ijAq X-Proofpoint-ORIG-GUID: Ok5TMgexn1KyPpBewFrZ9VpDM0f2ijAq 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=2025-01-16_07,2025-01-16_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxscore=0 bulkscore=0 clxscore=1015 adultscore=0 mlxlogscore=999 priorityscore=1501 suspectscore=0 spamscore=0 phishscore=0 impostorscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501160124 > > Rorie, this is to inform listeners on the host of the guest. > The guest itself already sees this "inside" with uevents triggered > by the AP bus code. > > Do you have a consumer for these events? There is a series of QEMU patches that register a notification handler for this event. When that handler gets called, it generates and queues a CRW to the guest indicating there is event information pending which will cause the AP bus driver to get notified of the AP configuration change via its ap_bus_cfg_chg notifier call. The QEMU series can be seen at: https://lore.kernel.org/qemu-devel/7171c479-5cb4-4748-ba37-da4cf2fac35b@linux.ibm.com/T/ Kind regards, A Krowiak