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

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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: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20220628143100.3228092-4-schnelle@linux.ibm.com
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
This commit is contained in:
Niklas Schnelle 2022-06-28 16:30:58 +02:00 committed by Bjorn Helgaas
parent fbed59ed87
commit db360b1ea7
1 changed files with 10 additions and 20 deletions
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30
drivers/pci/probe.c
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@ -2663,8 +2663,13 @@ int pci_scan_slot(struct pci_bus *bus, int devfn)
if (fn > 0)
dev->multifunction = 1;
} else if (fn == 0) {
/* function 0 is required */
break;
/*
* 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);
} while (fn >= 0);
@ -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);