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authorJakub Kicinski <jakub.kicinski@netronome.com>2018-06-29 22:08:52 +0200
committerBjorn Helgaas <bhelgaas@google.com>2018-06-29 22:08:52 +0200
commit38972375ef7bdc7dd989bcb48d5448662a95bca2 (patch)
tree16da6a4edc6b5f3de22c73f7eec6789298317870 /drivers/hwtracing
parentPCI: faraday: Add missing of_node_put() (diff)
downloadlinux-38972375ef7bdc7dd989bcb48d5448662a95bca2.tar.xz
linux-38972375ef7bdc7dd989bcb48d5448662a95bca2.zip
PCI/IOV: Reset total_VFs limit after detaching PF driver
The TotalVFs register in the SR-IOV capability is the hardware limit on the number of VFs. A PF driver can limit the number of VFs further with pci_sriov_set_totalvfs(). When the PF driver is removed, reset any VF limit that was imposed by the driver because that limit may not apply to other drivers. Before 8d85a7a4f2c9 ("PCI/IOV: Allow PF drivers to limit total_VFs to 0"), pci_sriov_set_totalvfs(pdev, 0) meant "we can enable TotalVFs virtual functions", and the nfp driver used that to remove the VF limit when the driver unloads. 8d85a7a4f2c9 broke that because instead of removing the VF limit, pci_sriov_set_totalvfs(pdev, 0) actually sets the limit to zero, and that limit persists even if another driver is loaded. We could fix that by making the nfp driver reset the limit when it unloads, but it seems more robust to do it in the PCI core instead of relying on the driver. The regression scenario is: nfp_pci_probe (driver 1) ... nfp_pci_remove pci_sriov_set_totalvfs(pf->pdev, 0) # limits VFs to 0 ... nfp_pci_probe (driver 2) nfp_rtsym_read_le("nfd_vf_cfg_max_vfs") # no VF limit from firmware Now driver 2 is broken because the VF limit is still 0 from driver 1. Fixes: 8d85a7a4f2c9 ("PCI/IOV: Allow PF drivers to limit total_VFs to 0") Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> [bhelgaas: changelog, rename functions] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
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