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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org, Jan Kiszka <jan.kiszka@siemens.com>,
	Benedikt Spranger <b.spranger@linutronix.de>
Subject: x86/PCI: Scan all functions during probing
Date: Tue, 9 Aug 2016 13:22:30 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.20.1608091318530.5388@nanos> (raw)

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. */

             reply	other threads:[~2016-08-09 11:24 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-09 11:22 Thomas Gleixner [this message]
2016-08-09 12:13 ` x86/PCI: Scan all functions during probing Lukas Wunner
2016-08-09 13:44 ` Bjorn Helgaas
2016-08-18 20:33   ` Bjorn Helgaas
2016-08-24  8:39     ` Thomas Gleixner
2016-08-24 11:13       ` Jan Kiszka
2016-08-24 17:23         ` Thomas Gleixner

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