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Fri, 17 Jan 2025 08:30:38 +0000 (GMT) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Fri, 17 Jan 2025 09:30:38 +0100 From: Harald Freudenberger To: Anthony Krowiak Cc: Rorie Reyes , 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 Subject: Re: [PATCH v1] s390/vfio-ap: Signal eventfd when guest AP configuration is changed Reply-To: freude@linux.ibm.com Mail-Reply-To: freude@linux.ibm.com In-Reply-To: References: <20250107183645.90082-1-rreyes@linux.ibm.com> <45d553cd050334029a6d768dc6639433@linux.ibm.com> Message-ID: <105ff0df576ac86c1cd2edd4e1a6478c@linux.ibm.com> X-Sender: freude@linux.ibm.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: CFcz3-cpfwUtJXnZxvLZmlY27nUWMuLo X-Proofpoint-GUID: CFcz3-cpfwUtJXnZxvLZmlY27nUWMuLo 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=2025-01-17_03,2025-01-16_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 spamscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 mlxscore=0 adultscore=0 malwarescore=0 mlxlogscore=999 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501170067 On 2025-01-16 17:46, Anthony Krowiak wrote: >> >> 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 Ok, so this way the AP bus of the guest finally get's it's config change callback invoked :-)