Hi Michael,
this patch (against your vhost branch) should fix the endianness issues
we saw on s390 that I mentioned on irc yesterday.
Both the config space and the stats seem to be fine endianness-wise,
but the pfns for inflate/deflate were not converted to little endian
for virtio-1 (the qemu code is correct).
Without the patch, I get an immediate crash on qemu master when
started via libvirt with currentMemory=0.5*Memory (thanks to
Christian for the hint) - as virtio-ccw is enabling virtio-1 by
default:
[ 3.273419] ------------[ cut here ]------------
[ 3.273424] Kernel BUG at 0000000000300df2 [verbose debug info unavailable]
[ 3.273617] illegal operation: 0001 ilc:1 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 3.273623] Modules linked in: autofs4
[ 3.273627] CPU: 2 PID: 1 Comm: systemd Not tainted 4.5.0-00798-g1181f16 #6
[ 3.273629] task: 000000003def8000 ti: 000000003deec000 task.ti: 000000003deec000
[ 3.273631] Krnl PSW : 0704d00180000000 0000000000300df2 (do_iter_readv_writev+0x2/0x90)
[ 3.273640] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 EA:3
Krnl GPRS: 000000003deefe30 0000000000008000 000000003bba8c00 000000003deefdb0
[ 3.273644] 000000003deeff08 00000000001b3e60 000000003deefda8 000003ffc18fde60
[ 3.273646] 0000000000000248 0000000000000000 000000003deeff08 0000000000000001
[ 3.273647] 000000003bba8c00 00000000001b3e60 0000000000301f08 000000003deefd00
[ 3.273655] Krnl Code:>0000000000300df2: 000 unknown
0000000000300df4: 0000 unknown
0000000000300df6: 0000 unknown
0000000000300df8: 0000 unknown
0000000000300dfa: 0000 unknown
0000000000300dfc: 0000 unknown
0000000000300dfe: 0000 unknown
0000000000300e00: 0000 unknown
[ 3.273665] Call Trace:
[ 3.273667] ([<0000000000301e86>] do_readv_writev+0x86/0x260)
[ 3.273669] [<0000000000302132>] vfs_writev+0x5a/0x78
[ 3.273671] [<000000000030305e>] SyS_writev+0x66/0xe8
[ 3.273677] [<000000000076955e>] system_call+0xd6/0x270
[ 3.273679] [<000003ff9d2f82c4>] 0x3ff9d2f82c4
[ 3.273680] INFO: lockdep is turned off.
[ 3.273681] Last Breaking-Event-Address:
[ 3.273683] [<0000000000769a60>] io_int_handler+0x17c/0x298
[ 3.273686]
[ 3.273688] Kernel panic - not syncing: Fatal exception: panic_on_oops
The crash is gone by either forcing the device to legacy (max_revision=0)
or by applying the patch below in the guest.
[There also have been reports of people getting immediate "Out of puff!"
messages, but I don't know how to reproduce that.]
Problems should presumably also arise with virtio-pci on big endian
platforms, but given that it took us some time to hit this in tests
with the always-modern virtio-ccw environment, I'm not surprised if
nobody hit that yet.
[As an aside: Should the virtio spec be a bit more clear on how the
queues for the balloon operate, or do we want to avoid spending more
time on the legacy balloon?]
The fix (this patch or something different) needs to be cc:stable,
I guess.
Cornelia Huck (1):
virtio-balloon: handle virtio-1 endianness
drivers/virtio/virtio_balloon.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--
2.6.6
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