[Xen-devel] domU jiffies not incrementing - timer issue? - Kernel 3.18.10 on Xen 4.5.0

[Mark <mark@xxxxxxxxxxxxxxx>]

Hi,Â

I have an issue where domUs will hang at boot if CONFIG_XOR_BLOCKS is enabled.

This is a PV domU on Xen which is running inside a Hyper-V virtual machine.

We have another installation (different hardware) working without any issues.

The last line output on the domU console is always:

 Â'xor: measuring software checksum speed'

We've added a line to see what's happening and jiffies are not incrementing.

diff -u crypto/xor.c.orig crypto/xor.c

--- crypto/xor.c.orig  2015-03-24 01:05:12.000000000 +0000

+++ crypto/xor.c    Â2015-03-30 18:14:21.269444139 +0100

@@ -81,8 +81,10 @@

    for (i = 0; i < 5; i++) {

        j = jiffies;

        count = 0;

- Â Â Â Â Â Â Â while ((now = jiffies) == j)

+ Â Â Â Â Â Â Â while ((now = jiffies) == j){

+ Â Â Â Â Â Â Â Â Â Â Â printk(KERN_INFO " Â %-10s: loop #%d jiffies=%ld\n", tmpl->name, i, j);

            cpu_relax();

+ Â Â Â Â Â Â Â }

        while (time_before(jiffies, now + 1)) {

            mb(); /* prevent loop optimzation */

            tmpl->do_2(BENCH_SIZE, b1, b2);

When we try to boot the DomU we will just get the debug line I added repeatedÂ

with the jiffies staying at the same value:

[ Â Â0.004000] Â Âprefetch64-sse: loop #0 jiffies=4294892296

[ Â Â0.004000] Â Âprefetch64-sse: loop #0 jiffies=4294892296

[ Â Â0.004000] Â Âprefetch64-sse: loop #0 jiffies=4294892296

... etc

The Dom0 kernel on this hardware works as expected i.e. finally producing

 Â'xor: using function':Â

[ Â Â0.532357] xor: measuring software checksum speed

[ Â Â0.534769] Â Âprefetch64-sse: loop #0 jiffies=4294892429

<snip>

[ Â Â0.566381] Â Âprefetch64-sse: loop #4 jiffies=4294892437

[ Â Â0.572008] Â Âprefetch64-sse: Â3805.000 MB/sec

[ Â Â0.574373] Â Âgeneric_sse: loop #0 jiffies=4294892439

<snip>

[ Â Â0.606367] Â Âgeneric_sse: loop #4 jiffies=4294892447

[ Â Â0.612005] Â Âgeneric_sse: Â3530.000 MB/sec

[ Â Â0.614374] xor: using function: prefetch64-sse (3805.000 MB/sec)

In an attempt to demonstrate that this isn't related to something in our domU

kernel configuration I've booted domU with the same working kernel from the

Dom0 and it gets stuck in the same place.

Note that the 'state' of xl list continues to stay empty for the domU with the

time incrementing:

Name                    ÂID  Mem VCPUs State Time(s)

Domain-0 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0 Â 800 Â Â 1 Â Â r----- Â Â 131.5

6-1 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â4 Â1000 Â Â 1 Â Â ------ Â Â1824.5

Attached are the logs from booting the same kernel as dom0 and domU along with

/proc/cpuinfo and xl dmesg.

Anyone have any ideas why it'd be getting stuck or how I can further debug this?

Thanks,Â

Mark

Attachment: dom0-dmesg.log
Description: Text Data

Attachment: domU-console.log
Description: Text Data

Attachment: proc-cpuinfo.out
Description: Binary data

Attachment: xl-dmesg.log
Description: Text Data

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