Hi Zhu,
           I was using the qemu command with "--cpu host". I removed that
and after that it is working fine for me. Now everything is working
perfectly fine.


Thanks,
Mohsin Kazmi


On Mon, Apr 20, 2015 at 2:16 PM, Mohsin Kazmi <mohsin.kazm...@gmail.com>
wrote:

> Hi Zhu,
>           I installed and enabled the --iasl=IASL at "configuration" for
> qemu and then "make" it.
>
> When i tried to delete the cpu1 after adding it using hotplug/unplug, I am
> facing the kernel panic at guest os. Kernel version
> (3.11.10-301.fc20.x86_64)
>
> [root@fedora20 ~]# [  208.733033] general protection fault: 0000 [#1] SMP
> [  208.733033] Modules linked in: nfsv3 rpcsec_gss_krb5 nfsv4 dns_resolver
> nfs fscache cfg80211 rfkill ppdev crct10dif_pclmul crc32_pclmul
> crc32c_intel ghash_clmulni_intel parport_pc parport i2c_piix4 serio_raw
> pvpanic microcode bochs_drm ttm drm_kms_helper drm nfsd auth_rpcgss nfs_acl
> lockd sunrpc virtio_net virtio_pci virtio_ring virtio ata_generic pata_acpi
> [  208.733033] CPU: 1 PID: 0 Comm: swapper/1 Not tainted
> 3.17.7-200.fc20.x86_64 #1
> [  208.733033] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.7.5.1-0-g8936dbb-20141113_115728-nilsson.home.kraxel.org 04/01/2014
> [  208.733033] task: ffff880139b7b110 ti: ffff880139bbc000 task.ti:
> ffff880139bbc000
> [  208.733033] RIP: 0010:[<ffffffff81058836>]  [<ffffffff81058836>]
> native_read_pmc+0x6/0x20
> [  208.733033] RSP: 0018:ffff88013fc83e20  EFLAGS: 00000083
> [  208.733033] RAX: 0000000000000001 RBX: ffff88013fc8b9e0 RCX:
> 0000000040000001
> [  208.733033] RDX: 00000000ffffffff RSI: 0000000000000001 RDI:
> 0000000040000001
> [  208.733033] RBP: ffff88013fc83e20 R08: ffff88013fc97098 R09:
> 0000000000000000
> [  208.733033] R10: 0000000000000001 R11: 0000000000000005 R12:
> ffffffff80000001
> [  208.733033] R13: ffff8800b994dc00 R14: ffff8800b994dd98 R15:
> 0000000000000010
> [  208.733033] FS:  0000000000000000(0000) GS:ffff88013fc80000(0000)
> knlGS:0000000000000000
> [  208.733033] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [  208.733033] CR2: 00007f2798f7c0b9 CR3: 0000000001c14000 CR4:
> 00000000000007e0
> [  208.733033] Stack:
> [  208.733033]  ffff88013fc83e58 ffffffff8102ab83 ffff88013fc8b9e0
> ffff8800b994dc00
> [  208.733033]  0000000000000004 ffff88013fc97104 ffff88013fc9708c
> ffff88013fc83e80
> [  208.733033]  ffffffff8102ac38 ffff8800b994dc00 ffff88013fc8b9e0
> ffff8800b994dc00
> [  208.733033] Call Trace:
> [  208.733033]  <IRQ>
> [  208.733033]  [<ffffffff8102ab83>] x86_perf_event_update+0x43/0xa0
> [  208.733033]  [<ffffffff8102ac38>] x86_pmu_stop+0x58/0xd0
> [  208.733033]  [<ffffffff8102acf2>] x86_pmu_del+0x42/0x130
> [  208.733033]  [<ffffffff8117c4b2>] event_sched_out.isra.75+0x102/0x1f0
> [  208.733033]  [<ffffffff8117c7f1>] __perf_remove_from_context+0x51/0xb0
> [  208.733033]  [<ffffffff8117c8e1>] __perf_event_exit_context+0x91/0xe0
> [  208.733033]  [<ffffffff8110a82d>]
> flush_smp_call_function_queue+0x5d/0x130
> [  208.733033]  [<ffffffff8110af43>]
> generic_smp_call_function_single_interrupt+0x13/0x60
> [  208.733033]  [<ffffffff810455e7>]
> smp_call_function_single_interrupt+0x27/0x40
> [  208.733033]  [<ffffffff8172ff7d>]
> call_function_single_interrupt+0x6d/0x80
> [  208.733033]  <EOI>
> [  208.733033]  [<ffffffff81058966>] ? native_safe_halt+0x6/0x10
> [  208.733033]  [<ffffffff8101e52f>] default_idle+0x1f/0xc0
> [  208.733033]  [<ffffffff8101eedf>] arch_cpu_idle+0xf/0x20
> [  208.733033]  [<ffffffff810d1e24>] cpu_startup_entry+0x344/0x380
> [  208.733033]  [<ffffffff811023dc>] ?
> clockevents_register_device+0xbc/0x120
> [  208.733033]  [<ffffffff81045f30>] start_secondary+0x210/0x2d0
> [  208.733033] Code: c0 48 c1 e2 20 89 0e 48 09 c2 48 89 d0 5d c3 66 0f 1f
> 44 00 00 55 89 f0 89 f9 48 89 e5 0f 30 31 c0 5d c3 66 90 55 89 f9 48 89 e5
> <0f> 33 89 c0 48 c1 e2 20 48 09 c2 48 89 d0 5d c3 66 2e 0f 1f 84
> [  208.733033] RIP  [<ffffffff81058836>] native_read_pmc+0x6/0x20
> [  208.733033]  RSP <ffff88013fc83e20>
> [  208.733033] ---[ end trace 01a347638d675891 ]---
> [  208.733033] Kernel panic - not syncing: Fatal exception in interrupt
> [  208.733033] Kernel Offset: 0x0 from 0xffffffff81000000 (relocation
> range: 0xffffffff80000000-0xffffffff9fffffff)
> [  208.733033] drm_kms_helper: panic occurred, switching back to text
> console
> [  208.733033] ---[ end Kernel panic - not syncing: Fatal exception in
> interrupt
>
>
> Can you please help me in that?
>
>
> On Mon, Apr 20, 2015 at 11:19 AM, Zhu Guihua <zhugh.f...@cn.fujitsu.com>
> wrote:
>
>>
>> On 04/16/2015 06:50 PM, Mohsin Kazmi wrote:
>>
>>  Hi Zhu,
>>            I am testing the hot unplug feature using your github branch
>> 'cpu-hotplug'. It is working fine when first time I added and deleted cpu.
>> But when I tried to add cpu second time, it showed me the following error:
>> (qemu) device_add kvm64-x86_64-cpu,apic-id=1,id=cpu1
>>             Duplicate ID 'cpu1' for device
>>
>>
>> Sorry for late reply.
>>
>> I guess you should use iasl and regenerate the ACPI tables.
>>
>> You can refer to the following 
>> issue:http://lists.nongnu.org/archive/html/qemu-devel/2014-09/msg02993.html
>>
>>
>> Thanks,
>> Zhu
>>
>>  I get from one of your patch (https://patchwork.ozlabs.org/patch/439485/)
>> commit message that cpu is not literally removed from qemu but guest is
>> unable to use it anymore. Do you know the way how I can reuse that cpu
>> which has already added and deleted once. Or unparking the cpu mechanism.
>>
>>  Thanks,
>>  Mohsin Kazmi
>>
>>
>>
>

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