[PATCH 2.6.34-rcX] Do not expect PCI devices to return zeroes in PCIe space
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From: Petr Vandrovec on 30 Apr 2010 23:30 Hello, openSUSE11.3 32bit kernels hang when installed to the VMware's VMs because Moorestown fixed capabilities detection code enters endless loop on Intel's AGP bridges (with device ID=7191). See https://bugzilla.kernel.org/show_bug.cgi?id=15888 for additional details. arch/x86/pci/mrst.c was introduced after 2.6.33, so only 2.6.34-rcX are affected. Thanks, Petr Vandrovec commit 11a35e56ad8275cbf62882d9c0dc2f17c2b5628b Author: Petr Vandrovec <petr(a)vandrovec.name> Date: Fri Apr 30 19:17:43 2010 -0700 Do not expect PCI devices to return zeroes in PCIe space There is no reason why old pre-PCIe/PCI-X devices should return zeroes when configuration space above 0x100 is accessed. If these devices decode just low 8 bits of register number, conventional space repeats 15 times in PCIe config space. And Moorestown parser for fixed bars then can enter endless loop when finding Intel AGP bridge device 0x7191 with secondary latency timer programmed to 0x40 - when such device is encountered, code will enter endless loop of reading registers 0x718 (reading 0x40010100) and 0x400 (reading 0x71918086). This change adds additional condition to the test: if device id/vendor match first PCIe capability, then device is not really PCIe. It should not cause any problems: fixed_bar_cap is invoked only on Intel's devices, so only time there is possibilty to have false match would be if first PCIe capability would have ID 0x8086, and even then that address of next capability pointer and capability version will match device ID seems highly unlikely. This fix unbreaks 32bit 2.6.33+ kernels configured with Moorestown support to boot on AMD rev 10h+ processors under VMware in VMs which lack PCIe support. Signed-off-by: Petr Vandrovec <petr(a)vandrovec.name> diff --git a/arch/x86/pci/mrst.c b/arch/x86/pci/mrst.c index 8bf2fcb..cd6c277 100644 --- a/arch/x86/pci/mrst.c +++ b/arch/x86/pci/mrst.c @@ -55,12 +55,16 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn) { int pos; u32 pcie_cap = 0, cap_data; + u32 devid; pos = PCIE_CAP_OFFSET; if (!raw_pci_ext_ops) return 0; + if (raw_pci_ops->read(pci_domain_nr(bus), bus->number, devfn, 0, 4, &devid)) + return 0; + while (pos) { if (raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number, devfn, pos, 4, &pcie_cap)) @@ -69,6 +73,9 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn) if (pcie_cap == 0xffffffff) return 0; + if (pcie_cap == devid && pos == PCIE_CAP_OFFSET) + return 0; + if (PCI_EXT_CAP_ID(pcie_cap) == PCI_EXT_CAP_ID_VNDR) { raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number, devfn, pos + 4, 4, &cap_data); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |