[PATCH 5.8 033/148] s390/pci: fix PF/VF linking on hot plug

Greg Kroah-Hartman
2020-08-24T08:33:18Z

From: Niklas Schnelle <schnelle@linux.ibm.com>

commit b97bf44f99155e57088e16974afb1f2d7b5287aa upstream.

Currently there are four places in which a PCI function is scanned
and made available to drivers:
1. In pci_scan_root_bus() as part of the initial zbus
creation.
2. In zpci_bus_add_devices() when registering
a device in configured state on a zbus that has already been
scanned.
3. When a function is already known to zPCI (in reserved/standby state)
and configuration is triggered through firmware by PEC 0x301.
4. When a device is already known to zPCI (in standby/reserved state)
and configuration is triggered from within Linux using
enable_slot().

The PF/VF linking step and setting of pdev->is_virtfn introduced with
commit e5794cf1a270 ("s390/pci: create links between PFs and VFs") was
only triggered for the second case, which is where VFs created through
sriov_numvfs usually land. However unlike some other platforms but like
POWER VFs can be individually enabled/disabled through
/sys/bus/pci/slots.

Fix this by doing VF setup as part of pcibios_bus_add_device() which is
called in all of the above cases.

Finally to remove the PF/VF links call the common code
pci_iov_remove_virtfn() function to remove linked VFs.
This takes care of the necessary sysfs cleanup.

Fixes: e5794cf1a270 ("s390/pci: create links between PFs and VFs")
Cc: <stable@vger.kernel.org> # 5.8: 2f0230b2f2d5: s390/pci: re-introduce zpci_remove_device()
Cc: <stable@vger.kernel.org> # 5.8
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/s390/pci/pci.c | 5 ++++-
arch/s390/pci/pci_bus.c | 27 +++++++++++++++------------
arch/s390/pci/pci_bus.h | 13 +++++++++++++
3 files changed, 32 insertions(+), 13 deletions(-)

--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -678,8 +678,11 @@ void zpci_remove_device(struct zpci_dev
struct pci_dev *pdev;

pdev = pci_get_slot(zbus->bus, zdev->devfn);
- if (pdev)
+ if (pdev) {
+ if (pdev->is_virtfn)
+ return zpci_remove_virtfn(pdev, zdev->vfn);
pci_stop_and_remove_bus_device_locked(pdev);
+ }
}

int zpci_create_device(struct zpci_dev *zdev)
--- a/arch/s390/pci/pci_bus.c
+++ b/arch/s390/pci/pci_bus.c
@@ -189,6 +189,19 @@ static inline int zpci_bus_setup_virtfn(
}
#endif

+void pcibios_bus_add_device(struct pci_dev *pdev)
+{
+ struct zpci_dev *zdev = to_zpci(pdev);
+
+ /*
+ * With pdev->no_vf_scan the common PCI probing code does not
+ * perform PF/VF linking.
+ */
+ if (zdev->vfn)
+ zpci_bus_setup_virtfn(zdev->zbus, pdev, zdev->vfn);
+
+}
+
static int zpci_bus_add_device(struct zpci_bus *zbus, struct zpci_dev *zdev)
{
struct pci_bus *bus;
@@ -219,20 +232,10 @@ static int zpci_bus_add_device(struct zp
}

pdev = pci_scan_single_device(bus, zdev->devfn);
- if (pdev) {
- if (!zdev->is_physfn) {
- rc = zpci_bus_setup_virtfn(zbus, pdev, zdev->vfn);
- if (rc)
- goto failed_with_pdev;
- }
+ if (pdev)
pci_bus_add_device(pdev);
- }
- return 0;

-failed_with_pdev:
- pci_stop_and_remove_bus_device(pdev);
- pci_dev_put(pdev);
- return rc;
+ return 0;
}

static void zpci_bus_add_devices(struct zpci_bus *zbus)
--- a/arch/s390/pci/pci_bus.h
+++ b/arch/s390/pci/pci_bus.h
@@ -29,3 +29,16 @@ static inline struct zpci_dev *get_zdev_

return (devfn >= ZPCI_FUNCTIONS_PER_BUS) ? NULL : zbus->function[devfn];
}
+
+#ifdef CONFIG_PCI_IOV
+static inline void zpci_remove_virtfn(struct pci_dev *pdev, int vfn)
+{
+
+ pci_lock_rescan_remove();
+ /* Linux' vfid's start at 0 vfn at 1 */
+ pci_iov_remove_virtfn(pdev->physfn, vfn - 1);
+ pci_unlock_rescan_remove();
+}
+#else /* CONFIG_PCI_IOV */
+static inline void zpci_remove_virtfn(struct pci_dev *pdev, int vfn) {}
+#endif /* CONFIG_PCI_IOV */