[Xen-devel] pvh+vcpus startup issue

[xen@xxxxxxxxxxxxxxxxxx]

Hi.  I have a domU.  Its params file has: vcpus = 8.  It will start with 
pv, but not type="pvh".  It will not start (on pvh) with vcpus = 7 or 6 
or 5.  It does start with vcpus = 4.
I diffed the xl -v create logs, no difference there on either startup.

I grabbed the domU console output for a vcpus = 5 start (attached).  It 
dies right after:
[    0.007110] cpu 3 spinlock event irq 23
[    0.007336] installing Xen timer for CPU 4

I think this issue is only affecting some CPUs.  So it might be related 
to some CPU calculation/allocation code?
I see xl info reports nr_nodes to be 1.  This is a server with two E5420 
CPUs.  I see other dual socket, dual CPU servers (e.g. E5410, E5310) 
that report at nr_nodes 1 .
I also see one newer CPU that I'd expect to have nr_nodes 2.

nr_cpus                : 20nr_nodes               : 
1cores_per_socket       : 10threads_per_core       : 2 model name    : 
Intel(R) Xeon(R) CPU E5-2640 v4 @ 2.40GHz
I note that a v3 version of that CPU reports nr_nodes 2 as I would expect.

nr_cpus                : 32nr_nodes               : 
2cores_per_socket       : 8threads_per_core       : 2 model name    : 
Intel(R) Xeon(R) CPU E5-2640 v3 @ 2.60GHz
# xl info
release                : 4.14.12-2.el6xen.x86_64
version                : #2 SMP Sat Jan 6 03:49:33 UTC 2018
machine                : x86_64
nr_cpus                : 8
max_cpu_id             : 7
nr_nodes               : 1
cores_per_socket       : 4
threads_per_core       : 1
cpu_mhz                : 2500
hw_caps                : 
bfebfbff:040ce3bd:20100800:00000001:00000000:00000000:00000000:00000000
virt_caps              : hvm
total_memory           : 64766
free_memory            : 15433
sharing_freed_memory   : 0
sharing_used_memory    : 0
outstanding_claims     : 0
free_cpus              : 0
xen_major              : 4
xen_minor              : 10
xen_extra              : .0
xen_version            : 4.10.0
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          :
xen_commandline        : dom0_mem=2048M cpufreq=xen dom0_max_vcpus=2 
dom0_vcpus_pin loglvl=info vcpu_migration_delay=1000
cc_compiler            : gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
cc_compile_by          : build
cc_compile_date        : Sun Jan  7 23:45:02 UTC 2018
build_id               : f61b02cac217640909b4c2d0f07ba50e0fe0f3d1
xend_config_format     : 4


cat /proc/cpuinfo

processor    : 0
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Xeon(R) CPU           E5420  @ 2.50GHz

...

processor    : 1
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Xeon(R) CPU           E5420  @ 2.50GHz

Possibly related to

https://lists.xenproject.org/archives/html/xen-devel/2018-01/msg01471.html

https://lists.xen.org/archives/html/xen-users/2018-01/msg00031.html

https://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=7209b8bf08700b1ed3b7dd15c6ca0b76f537ddb3 
"
x86: Don't use potentially incorrect CPUID values for topology information"

Regards, Peter

Attachment: vcpu5startup.txt
Description: Text document

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