x86/PCI: Scan all functions during probing

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	x86/PCI: Scan all functions during probing
Date	2016-08-09 13:30 +0200
Message-ID	<s4dom-6RJ-7@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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From: Benedikt Spranger <b.spranger@linutronix.de>

PCI and PCIBIOS probing only scans devices at function number 0/8/16/...
Subdevices (e.g. multiqueue) have function numbers which are not a
multiple of 8.

Simple hypervisors (e.g. Jailhouse) pass subdevices directly w/o providing
virtual PCI mappings like KVM. As a consequence a simple PCI passthrough from
Jailhouse to a linux guest is not able to detect such devices.

Changing the probe functions to scan all function numbers makes it work. This
has no side effects and there is no reason to force the 0/8/16... probing
scheme.

Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/pci/legacy.c |    2 +-
 drivers/pci/probe.c   |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/pci/legacy.c
+++ b/arch/x86/pci/legacy.c
@@ -42,7 +42,7 @@ void pcibios_scan_specific_bus(int busn)
 	if (pci_find_bus(0, busn))
 		return;
 
-	for (devfn = 0; devfn < 256; devfn += 8) {
+	for (devfn = 0; devfn < 256; devfn++) {
 		if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) &&
 		    l != 0x0000 && l != 0xffff) {
 			DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l);
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2063,7 +2063,7 @@ unsigned int pci_scan_child_bus(struct p
 	dev_dbg(&bus->dev, "scanning bus\n");
 
 	/* Go find them, Rover! */
-	for (devfn = 0; devfn < 0x100; devfn += 8)
+	for (devfn = 0; devfn < 0x100; devfn++)
 		pci_scan_slot(bus, devfn);
 
 	/* Reserve buses for SR-IOV capability. */

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Thread

x86/PCI: Scan all functions during probing Thomas Gleixner <tglx@linutronix.de> - 2016-08-09 13:30 +0200
  Re: x86/PCI: Scan all functions during probing Lukas Wunner <lukas@wunner.de> - 2016-08-09 14:20 +0200
  Re: x86/PCI: Scan all functions during probing Bjorn Helgaas <helgaas@kernel.org> - 2016-08-09 15:50 +0200

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