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690f430410
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
76 lines
1.6 KiB
C
76 lines
1.6 KiB
C
/*
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* legacy.c - traditional, old school PCI bus probing
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*/
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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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* Discover remaining PCI buses in case there are peer host bridges.
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* We use the number of last PCI bus provided by the PCI BIOS.
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*/
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static void pcibios_fixup_peer_bridges(void)
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{
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int n;
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if (pcibios_last_bus <= 0 || pcibios_last_bus > 0xff)
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return;
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DBG("PCI: Peer bridge fixup\n");
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for (n=0; n <= pcibios_last_bus; n++)
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pcibios_scan_specific_bus(n);
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}
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int __init pci_legacy_init(void)
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{
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if (!raw_pci_ops)
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return 1;
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pr_info("PCI: Probing PCI hardware\n");
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pcibios_scan_root(0);
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return 0;
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}
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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 += 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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pr_info("PCI: Discovered peer bus %02x\n", busn);
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pcibios_scan_root(busn);
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return;
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}
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}
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}
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EXPORT_SYMBOL_GPL(pcibios_scan_specific_bus);
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static int __init pci_subsys_init(void)
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{
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/*
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* The init function returns an non zero value when
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* pci_legacy_init should be invoked.
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*/
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if (x86_init.pci.init()) {
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if (pci_legacy_init()) {
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pr_info("PCI: System does not support PCI\n");
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return -ENODEV;
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}
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}
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pcibios_fixup_peer_bridges();
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x86_init.pci.init_irq();
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pcibios_init();
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return 0;
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}
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subsys_initcall(pci_subsys_init);
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