From 321b203122d6389fbcaced38fe670d4df7dda2e5 Mon Sep 17 00:00:00 2001 From: Niklas Schnelle Date: Wed, 12 Mar 2025 22:51:00 +0900 Subject: [PATCH] s390/pci: Fix SR-IOV for PFs initially in standby BugLink: https://bugs.launchpad.net/bugs/2102118 commit dc287e4c9149ab54a5003b4d4da007818b5fda3d upstream. Since commit 25f39d3dcb48 ("s390/pci: Ignore RID for isolated VFs") PFs which are not initially configured but in standby are considered isolated. That is they create only a single function PCI domain. Due to the PCI domains being created on discovery, this means that even if they are configured later on, sibling PFs and their child VFs will not be added to their PCI domain breaking SR-IOV expectations. The reason the referenced commit ignored standby PFs for the creation of multi-function PCI subhierarchies, was to work around a PCI domain renumbering scenario on reboot. The renumbering would occur after removing a previously in standby PF, whose domain number is used for its configured sibling PFs and their child VFs, but which itself remained in standby. When this is followed by a reboot, the sibling PF is used instead to determine the PCI domain number of it and its child VFs. In principle it is not possible to know which standby PFs will be configured later and which may be removed. The PCI domain and root bus are pre-requisites for hotplug slots so the decision of which functions belong to which domain can not be postponed. With the renumbering occurring only in rare circumstances and being generally benign, accept it as an oddity and fix SR-IOV for initially standby PFs simply by allowing them to create PCI domains. Cc: stable@vger.kernel.org Reviewed-by: Gerd Bayer Fixes: 25f39d3dcb48 ("s390/pci: Ignore RID for isolated VFs") Signed-off-by: Niklas Schnelle Signed-off-by: Alexander Gordeev Signed-off-by: Greg Kroah-Hartman (cherry picked from commit a1ecc325416aa6543b9c38b77fddfcf11e6feb4b linux-6.12.y) [koichiroden: follow-up fix from v6.12.14] Signed-off-by: Koichiro Den Signed-off-by: Stefan Bader --- arch/s390/pci/pci_bus.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c index 1b74a000ff64..56a786ca7354 100644 --- a/arch/s390/pci/pci_bus.c +++ b/arch/s390/pci/pci_bus.c @@ -171,7 +171,6 @@ void zpci_bus_scan_busses(void) static bool zpci_bus_is_multifunction_root(struct zpci_dev *zdev) { return !s390_pci_no_rid && zdev->rid_available && - zpci_is_device_configured(zdev) && !zdev->vfn; }