pci_iomap() often fails for VMs with passthrough devices

[marmarek]

Reported by joanna on 15 Aug 2011 19:59 UTC
When using a VM with assigned PCI device (such as e.g. a network card), sometimes the driver load fails at pci_iomap() function returning an error.

On my system this can be often observed when using external (Express Card) WiFi cards, assigned to some AppVM (of course I pass swiotlb=force to the VM's kernel).

E.g. (for iwlagn):

[  111.231349] cfg80211: Calling CRDA to update world regulatory domain
[  111.244409] cfg80211: World regulatory domain updated:
[  111.244423] cfg80211:     (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[  111.244430] cfg80211:     (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[  111.244437] cfg80211:     (2457000 KHz - 2482000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
[  111.244443] cfg80211:     (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
[  111.244449] cfg80211:     (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[  111.244455] cfg80211:     (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[  111.256301] Intel(R) Wireless WiFi Link AGN driver for Linux, in-tree:d
[  111.256317] Copyright(c) 2003-2011 Intel Corporation
[  111.256558] iwlagn 0000:00:00.0: setting latency timer to 64
[  111.256585] (NULL device *): pci_iomap failed

This happens non-deterministically. Might be related to physical memory fragmentation, although there is a distinctively different message for failure to alloce "pci memory" (and is not displayed in the case of the above error).

Migrated-From: https://wiki.qubes-os.org/ticket/329

[marmarek]

Comment by joanna on 10 Sep 2011 08:15 UTC
This likely also has been solved by the recent Xen patch, so closing this for now.

[marmarek]

Comment by joanna on 10 Sep 2011 08:15 UTC
This likely also has been solved by the recent Xen patch, so closing this for now.