[PATCH 4.19 30/50] PCI: Always allow probing with driver_override

Greg Kroah-Hartman
2019-09-18T06:24:05Z

From: Alex Williamson <alex.williamson@redhat.com>

commit 2d2f4273cbe9058d1f5a518e5e880d27d7b3b30f upstream.

Commit 0e7df22401a3 ("PCI: Add sysfs sriov_drivers_autoprobe to control
VF driver binding") introduced the sriov_drivers_autoprobe attribute
which allows users to prevent the kernel from automatically probing a
driver for new VFs as they are created. This allows VFs to be spawned
without automatically binding the new device to a host driver, such as
in cases where the user intends to use the device only with a meta
driver like vfio-pci. However, the current implementation prevents any
use of drivers_probe with the VF while sriov_drivers_autoprobe=0. This
blocks the now current general practice of setting driver_override
followed by using drivers_probe to bind a device to a specified driver.

The kernel never automatically sets a driver_override therefore it seems
we can assume a driver_override reflects the intent of the user. Also,
probing a device using a driver_override match seems outside the scope
of the 'auto' part of sriov_drivers_autoprobe. Therefore, let's allow
driver_override matches regardless of sriov_drivers_autoprobe, which we
can do by simply testing if a driver_override is set for a device as a
'can probe' condition.

Fixes: 0e7df22401a3 ("PCI: Add sysfs sriov_drivers_autoprobe to control VF driver binding")
Link: https://lore.kernel.org/lkml/155742996741.21878.569845487290798703.stgit@gimli.home
Link: https://lore.kernel.org/linux-pci/155672991496.20698.4279330795743262888.stgit@gimli.home/T/#u
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/pci/pci-driver.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -399,7 +399,8 @@ void __weak pcibios_free_irq(struct pci_
#ifdef CONFIG_PCI_IOV
static inline bool pci_device_can_probe(struct pci_dev *pdev)
{
- return (!pdev->is_virtfn || pdev->physfn->sriov->drivers_autoprobe);
+ return (!pdev->is_virtfn || pdev->physfn->sriov->drivers_autoprobe ||
+ pdev->driver_override);
}
#else
static inline bool pci_device_can_probe(struct pci_dev *pdev)