Re: Workings/effectiveness of the xen-acpi-processor driver

[Boris Ostrovsky <boris.ostrovsky@amd.com>]

On 05/03/2012 11:46 AM, Konrad Rzeszutek Wilk wrote:
> On Thu, May 03, 2012 at 04:47:46PM +0200, Stefan Bader wrote:
>> On 03.05.2012 14:58, Stefan Bader wrote:
>>
>>>>>>> So this shoudl solve the problem for the bootup processor.
>>>>>>>>
>>>>>>>> -boris
>>>>>>>>
>>>>>>>>
>>>>>>>>> +    };
>>>>>>>>> +    int ret = 0;
>>>>>>>>> +
>>>>>>>>> +    /* Shouldn't need this as APIC is turned off for PV, and we only
>>>>>>>>> +     * get called on the bootup processor. But just in case. */
>>>>>>>>> +    if (!xen_initial_domain() || smp_processor_id())
>>>>>>>>> +        return 0;
>>>>>>>>> +
>>>>>>>>> +    if (reg == APIC_LVR)
>>>>>>>>> +        return 0x10;
>>>>>>>>> +
>>>>>>>>> +    if (reg != APIC_ID)
>>>>>>>>> +        return 0;
>>>>>>>>> +
>>>>>>>>> +    ret = HYPERVISOR_dom0_op(&op);
>>>>>>>>> +    if (ret)
>>>>>>>>> +        return 0;
>>>>>>>>> +
>>>>>>>>> +    return op.u.pcpu_info.apic_id;


	return (op.u.pcpu_info.apic_id << 24);

indeed fixes the problem.

-boris


>>>>>>>>>    }
>>>>>>>>>
>>>>>>>>>    static void xen_apic_write(u32 reg, u32 val)
>>>
>>> I added debugging to all exit paths that could return 0 (which is what the
>>> boot_cpu_physical_apicid is set to with that patch. Which would only leave the
>>> case of the HV call returning the wrong value somehow...
>>>
>> Hmmm, so xen_apic_read is still correct...
>>
>> [    0.000000] ACPI: Local APIC address 0xfee00000
>> [    0.000000] xxx xen_apic_read(20)
>> [    0.000000] xxx xen_apic_read ->  10
>> [    0.000000] boot_cpu_physical_apicid = 0
>> [    0.000000] xxx xen_apic_read(30)
>> [    0.000000] +- apic version = 10
>>
>> there seems to be a slightly strange tweak (at least for me) in read_apic_id...
>>
>> static inline unsigned int read_apic_id(void)
>> {
>>          unsigned int reg;
>>
>>          reg = apic_read(APIC_ID); // calls apic->read(reg)
>>
>>          return apic->get_apic_id(reg);
>
> Duh!! Let me spin out a new patch that will do this.
>> }
>>
>>
>
>
>
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>