PCI: Scan all functions when running over Jailhouse
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
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@ -4,6 +4,7 @@
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#include <linux/init.h>
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#include <linux/export.h>
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#include <linux/pci.h>
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#include <asm/jailhouse_para.h>
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#include <asm/pci_x86.h>
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/*
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@ -34,13 +35,14 @@ int __init pci_legacy_init(void)
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void pcibios_scan_specific_bus(int busn)
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{
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int stride = jailhouse_paravirt() ? 1 : 8;
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int devfn;
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u32 l;
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if (pci_find_bus(0, busn))
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return;
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for (devfn = 0; devfn < 256; devfn += 8) {
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for (devfn = 0; devfn < 256; devfn += stride) {
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if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) &&
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l != 0x0000 && l != 0xffff) {
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DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l);
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@ -16,6 +16,7 @@
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#include <linux/pci-aspm.h>
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#include <linux/aer.h>
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#include <linux/acpi.h>
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#include <linux/hypervisor.h>
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#include <linux/irqdomain.h>
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#include <linux/pm_runtime.h>
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#include "pci.h"
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@ -2518,14 +2519,29 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
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{
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unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0;
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unsigned int start = bus->busn_res.start;
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unsigned int devfn, cmax, max = start;
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unsigned int devfn, fn, cmax, max = start;
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struct pci_dev *dev;
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int nr_devs;
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dev_dbg(&bus->dev, "scanning bus\n");
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/* Go find them, Rover! */
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for (devfn = 0; devfn < 0x100; devfn += 8)
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pci_scan_slot(bus, devfn);
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for (devfn = 0; devfn < 256; devfn += 8) {
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nr_devs = pci_scan_slot(bus, devfn);
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/*
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* The Jailhouse hypervisor may pass individual functions of a
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* multi-function device to a guest without passing function 0.
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* Look for them as well.
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*/
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if (jailhouse_paravirt() && nr_devs == 0) {
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for (fn = 1; fn < 8; fn++) {
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dev = pci_scan_single_device(bus, devfn + fn);
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if (dev)
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dev->multifunction = 1;
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}
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}
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}
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/* Reserve buses for SR-IOV capability */
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used_buses = pci_iov_bus_range(bus);
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