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Wed, 29 Oct 2025 09:41:51 GMT Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E4A1C58052; Wed, 29 Oct 2025 09:41:50 +0000 (GMT) Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 810675805D; Wed, 29 Oct 2025 09:41:48 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by smtpav05.dal12v.mail.ibm.com (Postfix) with ESMTP; Wed, 29 Oct 2025 09:41:48 +0000 (GMT) From: Niklas Schnelle Date: Wed, 29 Oct 2025 10:41:31 +0100 Subject: [PATCH v5 1/2] PCI: Fix isolated PCI function probing with ARI and SR-IOV Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20251029-ari_no_bus_dev-v5-1-d9a5eab67ed0@linux.ibm.com> References: <20251029-ari_no_bus_dev-v5-0-d9a5eab67ed0@linux.ibm.com> In-Reply-To: <20251029-ari_no_bus_dev-v5-0-d9a5eab67ed0@linux.ibm.com> To: Bjorn Helgaas Cc: Jan Kiszka , Huacai Chen , Bibo Mao , linux-s390 , loongarch@lists.linux.dev, Farhan Ali , Matthew Rosato , Tianrui Zhao , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Christian Borntraeger , Gerd Bayer , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Niklas Schnelle X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3621; i=schnelle@linux.ibm.com; h=from:subject:message-id; bh=dTkcEBl5gg6N/8Ckh8bxG5upJbEHSRnm22KBHzHO/xk=; b=owGbwMvMwCX2Wz534YHOJ2GMp9WSGDIZH0YYrMta8rLfMbLuU8n+soJNWznOra1sYA2yKN+fV vGpou1pRykLgxgXg6yYIsuiLme/dQVTTPcE9XfAzGFlAhnCwMUpABOpqGdk6H792zzHZNMrwdn6 eXxd0wKqt6ad8nmw6dva6+kWJxO1XzMyPI8p14s/dqPK/O3S3hO1Z+aK21QJNLI6f7SXWVvPXmH CCwA= X-Developer-Key: i=schnelle@linux.ibm.com; a=openpgp; fpr=9DB000B2D2752030A5F72DDCAFE43F15E8C26090 X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=K+gv3iWI c=1 sm=1 tr=0 ts=6901e161 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=x6icFKpwvdMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=gNLU74_c1yUKsMQYS-8A:9 a=QEXdDO2ut3YA:10 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-ORIG-GUID: 5aVzxZd_8NDjXLIEyfuoJhKssqGH9r6K X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDI4MDE2NiBTYWx0ZWRfX4XdmgPEPUuv1 9qOt8fopHetzAqds2n2TJi4oFXjwSDe5AgwYs4JDDSkDh1QlV23wTinY/CMGsdh2pI7aCxXJeUF 7hHHI2SBlpFuFWdiW5icXyFXRnwMcQaMeuAByACItiyu/zH9rj4/o6FGpy6MifnLj5Gh3enXRVa 13Z7HRrJiaery6HZHkZVhqjr7PNTuLHSyyim1iHGewRuwMN3PkuNgSlLWRycXhD4g+yDCHZZZIN 8we7NakoqUsXTMMA1luhfGGUsNvfkRcUTFC+l8gigXE9tkr0NoMtmVH8IQj6Y2DtJYG8bf9M+Fk wTExRIyoQ8+jy54J3jOZ9buxSVenxeCFoKsnTWn8nPZRzg+NK6GH1Y3LqB2coNAvI30nKOMlkM7 v/KMrGXTKInRNbW+VMh+YBz/3LQDHg== X-Proofpoint-GUID: 0RaOFpgZogZcd0rF0tuH0nOjX9HR2ST2 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-29_04,2025-10-22_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 impostorscore=0 suspectscore=0 adultscore=0 clxscore=1015 malwarescore=0 phishscore=0 spamscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2510280166 When the isolated PCI function probing mechanism is used in conjunction with ARI or SR-IOV it may not find all available PCI functions. In the case of ARI the problem is that next_ari_fn() always returns -ENODEV if dev is NULL and thus if fn 0 is missing the scan stops. For SR-IOV things are more complex. Here the problem is that the check for multifunction may fail. One example where this can occur is if the first passed-through function is a VF with devfn 8. Now in pci_scan_slot() this means it is fn 0 and thus multifunction doesn't get set. Since VFs don't get multifunction set via PCI_HEADER_TYPE_MFD it remains unset and probing stops even if there is a devfn 9. Now at the moment both of these issues are hidden on s390. The first one because ARI is detected as disabled as struct pci_bus's self is NULL even though firmware does enable and use ARI. The second issue is hidden as a side effect of commit 25f39d3dcb48 ("s390/pci: Ignore RID for isolated VFs"). This is because VFs are either put on their own virtual bus if the parent PF is not passed-through to the same instance or VFs are hotplugged once SR-IOV is enabled on the parent PF and then pci_scan_single_device() is used. Still especially the first issue prevents correct detection of ARI and the second might be a problem for other users of isolated function probing. Fix both issues by keeping things as simple as possible. If isolated function probing is enabled simply scan every possible devfn. Cc: stable@vger.kernel.org Fixes: 189c6c33ff42 ("PCI: Extend isolated function probing to s390") Link: https://lore.kernel.org/linux-pci/d3f11e8562f589ddb2c1c83e74161bd8948084c3.camel@linux.ibm.com/ Signed-off-by: Niklas Schnelle --- drivers/pci/probe.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 0ce98e18b5a876afe72af35a9f4a44d598e8d500..41dd1a339a994956a6bc7e1fea0fe0d55452a963 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2808,16 +2808,19 @@ static int next_ari_fn(struct pci_bus *bus, struct pci_dev *dev, int fn) return next_fn; } -static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn) +static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn, + bool isolated_fns) { - if (pci_ari_enabled(bus)) - return next_ari_fn(bus, dev, fn); + if (!isolated_fns) { + if (pci_ari_enabled(bus)) + return next_ari_fn(bus, dev, fn); + /* only multifunction devices may have more functions */ + if (dev && !dev->multifunction) + return -ENODEV; + } if (fn >= 7) return -ENODEV; - /* only multifunction devices may have more functions */ - if (dev && !dev->multifunction) - return -ENODEV; return fn + 1; } @@ -2859,10 +2862,12 @@ int pci_scan_slot(struct pci_bus *bus, int devfn) { struct pci_dev *dev; int fn = 0, nr = 0; + bool isolated_fns; if (only_one_child(bus) && (devfn > 0)) return 0; /* Already scanned the entire slot */ + isolated_fns = hypervisor_isolated_pci_functions(); do { dev = pci_scan_single_device(bus, devfn + fn); if (dev) { @@ -2876,10 +2881,10 @@ int pci_scan_slot(struct pci_bus *bus, int devfn) * a hypervisor that passes through individual PCI * functions. */ - if (!hypervisor_isolated_pci_functions()) + if (!isolated_fns) break; } - fn = next_fn(bus, dev, fn); + fn = next_fn(bus, dev, fn, isolated_fns); } while (fn >= 0); /* Only one slot has PCIe device */ -- 2.48.1