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Message-Id: <20220419102803.3430139-3-schnelle@linux.ibm.com>
Date: Tue, 19 Apr 2022 12:28:01 +0200
From: Niklas Schnelle <schnelle@...ux.ibm.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>,
Jan Kiszka <jan.kiszka@...mens.com>,
Matthew Rosato <mjrosato@...ux.ibm.com>,
Pierre Morel <pmorel@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org,
linux-s390@...r.kernel.org, linux-pci@...r.kernel.org
Subject: [PATCH v3 2/4] 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. Currently this is done with an extra loop duplicating the one
in pci_scan_slot(). By incorporating the check for jailhouse_paravirt()
into next_fn() we can instead do this as part of the normal
pci_scan_slot(). 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@...gle.com>
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
---
drivers/pci/probe.c | 28 +++++++---------------------
1 file changed, 7 insertions(+), 21 deletions(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 389aa1f9cb2c..a1e8f1e14c3d 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2602,10 +2602,11 @@ static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn)
if (dev && !dev->multifunction)
return -ENODEV;
/*
- * A function 0 is required but multifunction devices may
- * be non-contiguous so dev can be NULL otherwise.
+ * Usually a function 0 is required but the jailhouse hypervisor may
+ * pass individual functions. For non-contiguous multifunction devices
+ * some functions may also be missing.
*/
- if (!fn && !dev)
+ if (!fn && !dev && !jailhouse_paravirt())
return -ENODEV;
return (fn <= 6) ? fn + 1 : -ENODEV;
}
@@ -2855,29 +2856,14 @@ 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);
--
2.32.0
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