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Wed, 25 Mar 2026 15:16:24 +0000 (GMT) From: Gerd Bayer Subject: [PATCH v6 0/2] PCI: AtomicOps: Fix pci_enable_atomic_ops_to_root() Date: Wed, 25 Mar 2026 16:16:16 +0100 Message-Id: <20260325-fix_pciatops-v6-0-10bf19d76dd1@linux.ibm.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAED8w2kC/23P3WrDMAwF4Fcpvp6LLdV23Ku9xxjDP8pqWJMQd 6aj5N3nlI11JpdH4nxIN5ZpTpTZcXdjM5WU0zjUoJ92LJzc8E48xZoZCFBSCs37dH2bQnKXccr cUKdFRyF4gaxWppnq/s69vNZ8Svkyzl93vch1+gNJ8R8qkgtOMajOKeM10PNHGj6v++TP+zCe2 YoV+ANANpcUqEAUEsl6Q0CbAP4CWmD7SsEKWBsl+OB6L+0WcHgAJDbAYQXQByOcRotqC1APALS AqkDvojOA6Mh1LbAsyzeQ/xyisAEAAA== X-Change-ID: 20251106-fix_pciatops-7e8608eccb03 To: Bjorn Helgaas , Jay Cornwall , Felix Kuehling , Christian Borntraeger , Niklas Schnelle Cc: Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Leon Romanovsky , Alexander Schmidt , linux-s390@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-rdma@vger.kernel.org, Gerd Bayer , stable@vger.kernel.org X-Mailer: b4 0.14.2 X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: uQjG6wlYtha8bjQIqZwWRzjebZrwsQDO X-Authority-Analysis: v=2.4 cv=aMr9aL9m c=1 sm=1 tr=0 ts=69c3fc4d cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=vQOT1DpSoXcvsw1ccD4A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzI1MDEwNiBTYWx0ZWRfX2GpDRAcc6WTz 1HSdAIaG00oASGwIuCFa6XeHxOR0NoGEHIKMQFmACACBss1N41BmzFVu63Ha//zUCjHgN2AAJW+ K3tFA3s0pOfj7Swva3WEFJJB70AuF+HSXhBlnEMf9Nbwiuf20Ggwjg3bwowAFt5TrrkSeD/LwyV FXyC7FfxgwoG1JNG8nbzZvSqe+msGrPgxrbggPgxscqf82gMJsix/VmvjecEkp2jRpX4RxgScbn IogOwZZ/+ka6J378SkulTFktb6oPiryxPOpm+dsmgsakLYmC5NPs9TjRzSS1At6/UFm7VpSB17+ bNOrHq6UK8CRkNtMG7dLQGqt2vb2fGON2mHVICp2M0XIblt2PAXH/XtUXLSOgAi5uCy6ud1nJkX r455av+7ObpP8nAdwhLzF7n90SutxmmgOm88oXVxt6NDvJ7Tmy/q49X9Aae+ykrScIEbe6aSuoy HZo88bJJ0GlPWMxv7EQ== X-Proofpoint-GUID: joWoaCiOBWI4xkTdCkeMdT5UmKbpaHg5 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-25_04,2026-03-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 lowpriorityscore=0 adultscore=0 impostorscore=0 malwarescore=0 suspectscore=0 phishscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603250106 Hi Bjorn et al. On s390, AtomicOp Requests are enabled on a PCI function that supports them, despite the helper being ignorant about the root port's capability to supporting their completion. Patch 1: Fix the logic in pci_enable_atomic_ops_to_root() Patch 2: Update references to PCIe spec in that function. I did test that the issue is fixed with these patches. Also, I verified that on a Mellanox/Nvidia ConnectX-6 adapter plugged straight into the root port of a x86 system still gets AtomicOp Requests enabled. Due to lacking the required hardware, I did not test this with any PCIe switches between root port and endpoint. So test exposure to other environments is highly appreciated. One particularly rare setup is a RCiEP that might act as a AtomicOps Requestor - but was subject to a regression in v4 as reported by Sashiko. v5 of this series tries to make no functional changes for that class of devices either. Signed-off-by: Gerd Bayer --- Changes in v6: - Incorporate Ilpo's editorial comments. - Correct logic in pci_is_atomicops_capable_rp() (annotated by Sashiko) - Link to v5: https://lore.kernel.org/r/20260323-fix_pciatops-v5-0-fada7233aea8@linux.ibm.com Changes in v5: - Introduce new pcibios_connects_to_atomicops_capable_rc() so arch's can declare AtomicOps support outside of PCIe config space. Defaults to "true" - except s390. - rebase to 7.0-rc5 - Link to v4: https://lore.kernel.org/r/20260313-fix_pciatops-v4-0-93bc70a63935@linux.ibm.com Changes in v4: - drop patch 1 - it will become the base of a new series - previous patch 2, now 1: reword commit message - add a new patch to update references to PCI spec within pci_enable_atomic_ops_to_root() - rebase to latest master - Link to v3: https://lore.kernel.org/r/20260306-fix_pciatops-v3-0-99d12bcafb19@linux.ibm.com Changes in v3: - rebase to 7.0-rc2 - gentle ping - add netdev and rdma lists for awareness - Link to v2: https://lore.kernel.org/r/20251216-fix_pciatops-v2-0-d013e9b7e2ee@linux.ibm.com Changes in v2: - rebase to 6.19-rc1 - otherwise unchanged to v1 - Link to v1: https://lore.kernel.org/r/20251110-fix_pciatops-v1-0-edc58a57b62e@linux.ibm.com --- Gerd Bayer (2): PCI: AtomicOps: Do not enable without support in root complex PCI: AtomicOps: Update references to PCIe spec arch/s390/pci/pci.c | 5 +++++ drivers/pci/pci.c | 54 +++++++++++++++++++++++++++++++++-------------------- include/linux/pci.h | 1 + 3 files changed, 40 insertions(+), 20 deletions(-) --- base-commit: c369299895a591d96745d6492d4888259b004a9e change-id: 20251106-fix_pciatops-7e8608eccb03 Best regards, -- Gerd Bayer