From 690f4304104f37e473bd5e43fc5247f5cd35b225 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Wed, 7 Mar 2018 08:39:13 +0100 Subject: 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 Signed-off-by: Jan Kiszka Signed-off-by: Thomas Gleixner Reviewed-by: Andy Shevchenko Acked-by: Bjorn Helgaas Cc: jailhouse-dev@googlegroups.com Cc: Benedikt Spranger 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 --- arch/x86/pci/legacy.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/x86/pci') diff --git a/arch/x86/pci/legacy.c b/arch/x86/pci/legacy.c index 1cb01abcb1be..dfbe6ac38830 100644 --- a/arch/x86/pci/legacy.c +++ b/arch/x86/pci/legacy.c @@ -4,6 +4,7 @@ #include #include #include +#include #include /* @@ -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); -- cgit v1.2.3