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Xen guests cannot make use of all CPU features, and in some cases they are even risky to be advertised. One such feature is CONSTANT_TSC. This feature prevents the TSC (Time Stamp Counter) from being marked as unstable, which allows the sched_clock_stable option to be enabled. Having the sched_clock_stable option enabled is problematic for Xen PV guests because the sched_clock() function has been overridden with the xen_sched_clock() function, which is not synchronized between virtual CPUs. This update provides a patch, which sets all x86_power features to 0 as a preventive measure against other potentially dangerous assumptions the kernel could make based on the features, fixing this issue.
(In reply to comment #5)
> So is this an ack from kernel QE?
no, this is from Virt QE, we performed these tests from xen userspace with RHEL6.1 guest to avoid regression. Kernel QE are updating the kernel Tier1/2 test results in https://errata.devel.redhat.com/errata/show/11253 . Both the sides should get pass before verify this bug.
Have any tier1, tier2 tests been run against the new kernel? Are there any beaker tests that may test the specific issue of the guest crashing?
If there are any I will run them in the ec2 env. Thanks
Kernel Tier1 tests passed, Tier2 tests was still running.
We chose some specific tests for the bug in Tier2 tests, following tests were included:
/kernel/power-management/multi-thread-gettimeofday
/kernel/power-management/multi-thread-clock_gettime
/kernel/power-management/time-warp-test
/kernel/power-management/clock_gettime
/kernel/power-management/diff-clock-source
/kernel/stress/racer
/kernel/vm/193695
/kernel/distribution/ltp/20100831
/kernel/misc/autotest_r5278
I ever reproduced the bug in-house twice.
Host：
RHEL5.3 and kernel 2.6.18-128.1.10.el5
Guest：
RHEL6.1 and kernel 2.6.32-131.3.1.el6
See the log rhel6u1_x86_64_pv_install.log in
https://beaker.engineering.redhat.com/jobs/95043
And rhel6u1_i386_pv_install.log in
https://beaker.engineering.redhat.com/jobs/94623
At the same time, we found user-space packages xen and xen-libs in RHEL5.3 don't support RHEL6.1 installation as a guest. Then I retested under another configuration:
Host：
RHEL5.6 and kernel 2.6.18-238.12.1.el5
Guest：
RHEL6.1 and kernel 2.6.32-131.4.1.el6
Now the jobs on architectures Intel Nehalem and Intel system without nonstop_tsc flag are still queuing. The finished ones have passed our regression tests. For instance:
https://beaker.engineering.redhat.com/jobs/96462
(In reply to comment #12)
> At the same time, we found user-space packages xen and xen-libs in RHEL5.3
> don't support RHEL6.1 installation as a guest.
The best config for testing would be 5.3 kernel-xen and 5.6/7 xen userspace, and 2.6.32-131.4.1.el6 for the guest kernel.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
http://rhn.redhat.com/errata/RHBA-2011-0874.html