Re: Failure to boot HVM guest with more than 32 VCPUS

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> writes:

> On August 13, 2015 4:20:11 AM EDT, Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
>>"Hao, Xudong" <xudong.hao@intel.com> writes:
>>
>>>> -----Original Message-----
>>>> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
>>>> Sent: Wednesday, August 12, 2015 5:40 PM
>>>> To: Hao, Xudong
>>>> Cc: xen-devel@lists.xen.org
>>>> Subject: Re: [Xen-devel] Failure to boot HVM guest with more than 32
>>>> VCPUS
>>>> 
>>>> "Hao, Xudong" <xudong.hao@intel.com> writes:
>>>> 
>>>> > Hi,
>>>> >
>>>> > In X86_64 platform, we noticed an issue that Xen boot a RHEL6u6 or
>>>> > Fedora22 guest, when configure the VCPU more than 32, the guest
>>will
>>>> > fail to boot up.
>>>> 
>>>> The issue is well-known for RHEL6.6 (and is fixed in 6.7 and in
>>6.6.z)
>>>> but Fedora22 should boot. The log below is from RHEL6.6, can you
>>please
>>>> provide one from Fedora?
>>>> 
>>>
>>> Vitaly,
>>>
>>> Thanks for quick response. Is the fix in guest pv driver?
>>
>>The fix is in RHEL6 kernel, prior to it there is no support for
>>vcpu_info outside of shared_info and so only 32 vcpus are supported.
>
> Is the patch available somewhere? Or is it the one I had posted some time ago?
>

These are upstream commit ids (linux.git):
c06ee78d73fd24e8d8a65f16380f6a0551107e1b "xen: support large numbers of CPUs with vcpu info placement"
90d4f5534d14815bd94c10e8ceccc57287657ecc "xen:pvhvm: enable PVHVM VCPU placement when using more than 32 CPUs."
d5b17dbff83d63fb6bf35daec21c8ebfb8d695b5 "xen/smp/pvhvm: Don't point per_cpu(xen_vpcu, 33 and larger) to shared_info"

-- 
  Vitaly