| Message ID | 20220628143100.3228092-4-schnelle@linux.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | PCI: Rework pci_scan_slot() and isolated PCI functions | expand |
On 6/28/22 16:30, Niklas Schnelle wrote: > The special case of the jailhouse hypervisor passing through individual > PCI functions handles scanning for PCI functions even if function 0 does > not exist. Currently this is 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. > > Cc: Jan Kiszka <jan.kiszka@siemens.com> > Link: https://lore.kernel.org/linux-pci/20220408224514.GA353445@bhelgaas/ > Suggested-by: Bjorn Helgaas <bhelgaas@google.com> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > --- > drivers/pci/probe.c | 30 ++++++++++-------------------- > 1 file changed, 10 insertions(+), 20 deletions(-) > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index 2c737dce757e..a18e07e6a7df 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -2662,8 +2662,13 @@ 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 which passes through individual PCI > + * functions. > + */ > + if (!jailhouse_paravirt()) > + break; > } > fn = next_fn(bus, dev, fn); > } while (fn >= 0); > @@ -2862,29 +2867,14 @@ 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); > Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 2c737dce757e..a18e07e6a7df 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2662,8 +2662,13 @@ 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 which passes through individual PCI + * functions. + */ + if (!jailhouse_paravirt()) + break; } fn = next_fn(bus, dev, fn); } while (fn >= 0); @@ -2862,29 +2867,14 @@ 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);
The special case of the jailhouse hypervisor passing through individual PCI functions handles scanning for PCI functions even if function 0 does not exist. Currently this is 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. Cc: Jan Kiszka <jan.kiszka@siemens.com> Link: https://lore.kernel.org/linux-pci/20220408224514.GA353445@bhelgaas/ Suggested-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> --- drivers/pci/probe.c | 30 ++++++++++-------------------- 1 file changed, 10 insertions(+), 20 deletions(-)