Re: [Xen-devel] xl vcpu-set <guest> <nr> does not work properly.

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, Dec 04, 2013 at 02:57:24PM -0500, Konrad Rzeszutek Wilk wrote:
> When I try this with the "SeaBIOS" QEMU it does not hotplug
> all of the CPUs and it complains about the existing ones:
> 
> -bash-4.1# xl vcpu-list
> Name                                ID  VCPU   CPU State   Time(s) CPU
> Affinity
> Domain-0                             0     0    1   -b-      87.1  any
> cpu
> Domain-0                             0     1    2   -b-      14.4  any
> cpu
> Domain-0                             0     2    3   -b-      11.0  any
> cpu
> Domain-0                             0     3    0   r--      13.7  any
> cpu
> latest                               7     0    3   -b-      10.9  any
> cpu
> latest                               7     1    0   -b-       1.7  any
> cpu
> latest                               7     2    -   --p       0.0  any
> cpu
> latest                               7     3    -   --p       0.0  any
> cpu
> -bash-4.1# xl vcpu-set 7 4
> libxl: error: libxl_qmp.c:287:qmp_handle_error_response: received an
> error message from QMP server: Unable to add CPU: 0, it already exists
> libxl: error: libxl_qmp.c:287:qmp_handle_error_response: received an
> error message from QMP server: Unable to add CPU: 1, it already exists

That because I could not know which CPU where enable in QEMU with v1.3.
That should be possible know. I will look at it.

> -bash-4.1# xl vcpu-list
> Name                                ID  VCPU   CPU State   Time(s) CPU
> Affinity
> Domain-0                             0     0    0   -b-      87.4  any
> cpu
> Domain-0                             0     1    3   -b-      14.6  any
> cpu
> Domain-0                             0     2    2   -b-      11.1  any
> cpu
> Domain-0                             0     3    1   r--      13.7  any
> cpu
> latest                               7     0    2   -b-      11.7  any
> cpu
> latest                               7     1    1   -b-       1.7  any
> cpu
> latest                               7     2    3   -b-       0.0  any
> cpu
> 
> And sure enough - in the guest it only added one CPU:
> 
> [   85.720139] CPU2 has been hot-added
> [   85.726409] installing Xen timer for CPU 2
> [   85.735674] smpboot: Booting Node 0 Processor 2 APIC 0x4
> [   85.755080] cpu 2 spinlock event irq 86
> [   85.763671] microcode: CPU2 sig=0x206a7, pf=0x2, revision=0x28
> [   85.770669] Will online and init hotplugged CPU: 2
> 
> Perhaps the SeaBIOS/new qemu needs variants of:
> 
> f62079c piix4acpi, xen, hotplug: Fix race with ACPI AML code and hotplug.
> e28e062 piix4acpi, xen: Clarify that the qemu_set_irq calls just do an IRQ 
> pulse.
> 2133c38 piix4acpi, xen, vcpu hotplug: Split the notification from the changes

Yes, we should fix that in QEMU.

Thanks for reporting, I will work on it.

-- 
Anthony PERARD

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