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PCI: Scan all functions when running over Jailhouse

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Per PCIe r4.0, sec 7.5.1.1.9, multi-function devices are required to have a
function 0.  Therefore, Linux scans for devices at function 0 (devfn
0/8/16/...) and only scans for other functions if function 0 has its
Multi-Function Device bit set or ARI or SR-IOV indicate there are more
functions.

The Jailhouse hypervisor may pass individual functions of a multi-function
device to a guest without passing function 0, which means a Linux guest
won't find them.

Change Linux PCI probing so it scans all function numbers when running as a
guest over Jailhouse.

This is technically prohibited by the spec, so it is possible that PCI
devices without the Multi-Function Device bit set may have unexpected
behavior in response to this probe.

Originally-by: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: jailhouse-dev@googlegroups.com
Cc: Benedikt Spranger <b.spranger@linutronix.de>
Cc: linux-pci@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Link: https://lkml.kernel.org/r/06e279b2a3e06cf6689ab3975f8ab592bba02362.1520408357.git.jan.kiszka@siemens.com
This commit is contained in:
Jan Kiszka
2018-03-07 08:39:13 +01:00
committed by Thomas Gleixner
parent 63338a38db
commit 690f430410
2 changed files with 22 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/pci/legacy.c
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@@ -4,6 +4,7 @@
#include <linux/init.h>
#include <linux/export.h>
#include <linux/pci.h>
#include <asm/jailhouse_para.h>
#include <asm/pci_x86.h>
/*
@@ -34,13 +35,14 @@ int __init pci_legacy_init(void)
void pcibios_scan_specific_bus(int busn)
{
int stride = jailhouse_paravirt() ? 1 : 8;
int devfn;
u32 l;
if (pci_find_bus(0, busn))
return;
for (devfn = 0; devfn < 256; devfn += 8) {
for (devfn = 0; devfn < 256; devfn += stride) {
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);