Commit db360b1e authored by Niklas Schnelle's avatar Niklas Schnelle Committed by Bjorn Helgaas
Browse files

PCI: Move jailhouse's isolated function handling to pci_scan_slot() 

The special case of the jailhouse hypervisor passing through individual PCI
functions handles scanning for PCI functions even if function 0 does not
exist. Previously this was done with an extra loop duplicating the one in
pci_scan_slot(). By incorporating the check for jailhouse_paravirt() into
pci_scan_slot() we can instead do this as part of the normal slot scan.
Note that with the assignment of dev->multifunction gated by fn > 0 we set
dev->multifunction unconditionally for all functions if function 0 is
missing just as in the existing jailhouse loop.

The only functional change is that we now call pcie_aspm_init_link_state()
for these functions, but this already happened if function 0 was passed
through and should not be a problem.

Link: https://lore.kernel.org/linux-pci/20220408224514.GA353445@bhelgaas/


Suggested-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20220628143100.3228092-4-schnelle@linux.ibm.com


Signed-off-by: default avatarNiklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarPierre Morel <pmorel@linux.ibm.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
parent fbed59ed

drivers/pci/probe.c

+10 −20
Original line number Diff line number Diff line
@@ -2663,7 +2663,12 @@ int pci_scan_slot(struct pci_bus *bus, int devfn) 
			if (fn > 0)

				dev->multifunction = 1;

		} else if (fn == 0) {

			/* function 0 is required */

			/*

			 * Function 0 is required unless we are running on

			 * a hypervisor that passes through individual PCI

			 * functions.

			 */

			if (!jailhouse_paravirt())

				break;

		}

		fn = next_fn(bus, dev, fn);
@@ -2863,29 +2868,14 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus, 
{

	unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0;

	unsigned int start = bus->busn_res.start;

	unsigned int devfn, fn, cmax, max = start;

	unsigned int devfn, cmax, max = start;

	struct pci_dev *dev;

	int nr_devs;



	dev_dbg(&bus->dev, "scanning bus\n");



	/* Go find them, Rover! */

	for (devfn = 0; devfn < 256; devfn += 8) {

		nr_devs = pci_scan_slot(bus, devfn);



		/*

		 * The Jailhouse hypervisor may pass individual functions of a

		 * multi-function device to a guest without passing function 0.

		 * Look for them as well.

		 */

		if (jailhouse_paravirt() && nr_devs == 0) {

			for (fn = 1; fn < 8; fn++) {

				dev = pci_scan_single_device(bus, devfn + fn);

				if (dev)

					dev->multifunction = 1;

			}

		}

	}

	for (devfn = 0; devfn < 256; devfn += 8)

		pci_scan_slot(bus, devfn);



	/* Reserve buses for SR-IOV capability */

	used_buses = pci_iov_bus_range(bus);