Re: [Xen-devel] Xen-unstable + linux 4.1-mergewindow: problems with PV guest pci passthrough: pcifront pci-0: pciback not responding!!!

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Hello Sander,

Monday, April 27, 2015, 5:48:00 PM, you wrote:

> Hi David / Konrad,

> Here the other problem i found, which is introduced somewhere in the 
> 4.1 mergewindow:

> on 4.1.0-rc1 (with the one revert to get things booting) i get this in
> the PV Guest console:

> [    0.517392] crc32c_combine: 8373 self tests passed
> [    0.517608] pci_hotplug: PCI Hot Plug PCI Core version: 0.5
> [    0.517655] pciehp: PCI Express Hot Plug Controller Driver version: 0.4
> [    0.517677] cpcihp_generic: Generic port I/O CompactPCI Hot Plug Driver 
> version: 0.1
> [    0.517684] cpcihp_generic: not configured, disabling.
> [    0.517700] shpchp: Standard Hot Plug PCI Controller Driver version: 0.4
> [    0.517713] acpiphp_ibm: ibm_acpiphp_init: acpi_walk_namespace failed
> [    0.519849] usbcore: registered new interface driver udlfb
> [    0.613289] xen:xen_evtchn: Event-channel device installed
> [    0.613436] pcifront pci-0: Installing PCI frontend
> [    0.613578] pcifront pci-0: Creating PCI Frontend Bus 0000:00
> [    0.613616] pcifront pci-0: PCI host bridge to bus 0000:00
> [    0.613624] pci_bus 0000:00: root bus resource [io  0x0000-0xffff]
> [    0.613631] pci_bus 0000:00: root bus resource [mem 
> 0x00000000-0xffffffffffff]
> [    0.613638] pci_bus 0000:00: root bus resource [bus 00-ff]
> [    0.616672] pcifront pci-0: pciback not responding!!!
> [    2.613762] clocksource tsc: mask: 0xffffffffffffffff max_cycles: 
> 0x2e20fd6f2ba, max_idle_ns: 440795302556 ns
> [    2.614275] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [    2.614682] Linux agpgart interface v0.103
> [    2.614731] Hangcheck: starting hangcheck timer 0.9.1 (tick is 180 
> seconds, margin is 60 seconds).
> [    2.614762] [drm] Initialized drm 1.1.0 20060810
> [    2.614789] [drm] radeon kernel modesetting enabled.
> [    2.616529] brd: module loaded
> [    2.617844] loop: module loaded
> [    2.620008] pcifront pci-0: pciback not responding!!!
> [    4.621490] pcifront pci-0: pciback not responding!!!
> [    6.621866] pcifront pci-0: pciback not responding!!!
> [    8.622421] pcifront pci-0: pciback not responding!!!
> etc. etc. etc.


> Where on 4.0.0 it get:

> [    0.442554] shpchp: Standard Hot Plug PCI Controller Driver version: 0.4
> [    0.442583] acpiphp_ibm: ibm_acpiphp_init: acpi_walk_namespace failed
> [    0.443293] pcifront pci-0: Allocated pdev @ 0xffff88001ab23c00 
> pdev->sh_info @ 0xffff88001937f000
> [    0.444885] pcifront pci-0: publishing successful!
> [    0.445302] usbcore: registered new interface driver udlfb
> [    0.445829] xen:xen_evtchn: Event-channel device installed
> [    0.446499] pcifront pci-0: Installing PCI frontend
> [    0.446715] pcifront pci-0: Creating PCI Frontend Bus 0000:00
> [    0.446951] pcifront pci-0: PCI host bridge to bus 0000:00
> [    0.446960] pci_bus 0000:00: root bus resource [io  0x0000-0xffff]
> [    0.446968] pci_bus 0000:00: root bus resource [mem 
> 0x00000000-0xffffffffffff]
> [    0.446988] pci_bus 0000:00: root bus resource [bus 00-ff]
> [    0.447002] pci_bus 0000:00: scanning bus
> [    0.447140] pci 0000:00:00.0: [13f6:0111] type 00 class 0x040100
> [    0.447520] pci 0000:00:00.0: reg 0x10: [io  0x7800-0x78ff]
> [    0.449148] pci 0000:00:00.0: supports D1 D2
> [    0.449791] pci_bus 0000:00: fixups for bus
> [    0.449794] pci_bus 0000:00: bus scan returning with max=00
> [    0.450604] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [    0.451991] Linux agpgart interface v0.103
> [    0.452160] Hangcheck: starting hangcheck timer 0.9.1 (tick is 180 
> seconds, margin is 60 seconds).
> [    0.452222] [drm] Initialized drm 1.1.0 20060810
> [    0.452300] [drm] radeon kernel modesetting enabled.
> [    0.462384] pcifront pci-0: claiming resource 0000:00:00.0/0

> But i thought the patches that would change pci bus scanning were destined 
> for 
> 4.2 though ...

> --
> Sander

Hi David / Konrad,

I have bisected this one .. it leads to:

commit 97badf873ab60e841243b66133ff9eff2a46ef29
Author: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Date:   Fri Apr 3 23:23:37 2015 +0200

device property: Make it possible to use secondary firmware nodes

Since i didn't see it directly related to pci-front, i double checked by 
reverting this commit(and 9b73262ccbf2fb0060303f047863214269e64f9a since it 
build depends on the other) on 4.1-rc2.

Reverting in the guest kernel indeed makes pci-front work correct again.

--
Sander


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