linux-kernel - [PATCH] PCI: Always allow probing with driver

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Date:   Thu, 09 May 2019 13:27:22 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     linux-pci@...r.kernel.org
Cc:     bhelgaas@...gle.com, linux-kernel@...r.kernel.org,
        myron.stowe@...hat.com, bodong@...lanox.com, eli@...lanox.com,
        laine@...hat.com
Subject: [PATCH] PCI: Always allow probing with driver_override

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/linux-pci/155672991496.20698.4279330795743262888.stgit@gimli.home/T/#u
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
---

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

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index da7b82e56c83..9b9e9c63cde8 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -399,7 +399,8 @@ void __weak pcibios_free_irq(struct pci_dev *dev)
 #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)