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Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt()

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2016-10-24 22:32 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>
>
> On 19/10/2016 16:30, Wanpeng Li wrote:
>> Cc Radim,
>> 2016-10-19 22:10 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>>>
>>>
>>> On 19/10/2016 16:01, Wanpeng Li wrote:
>>>> 2016-10-18 8:01 GMT+08:00 Wanpeng Li <kernellwp@gmail.com>:
>>>>> 2016-10-17 18:08 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>>>>> [...]
>>>>>>>> Something like the below avoids all that. Paravirt will still need fixing.
>>>>>>>
>>>>>>> kvm_guest_apic_eoi_write
>>>>>>>  -> native_apic_msr_write
>>>>>>
>>>>>> kvm_guest_apic_eoi_write can use native_apic_msr_eoi_write too:
>>>>>>
>>>>>> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
>>>>>> index f5aaf6c83222..9769d76a62c4 100644
>>>>>> --- a/arch/x86/include/asm/apic.h
>>>>>> +++ b/arch/x86/include/asm/apic.h
>>>>>> @@ -174,7 +174,7 @@ static inline void disable_local_APIC(void) { }
>>>>>>  static inline void lapic_update_tsc_freq(void) { }
>>>>>>  #endif /* !CONFIG_X86_LOCAL_APIC */
>>>>>>
>>>>>> -#ifdef CONFIG_X86_X2APIC
>>>>>> +#if defined CONFIG_X86_X2APIC || defined CONFIG_KVM_GUEST
>>>>>
>>>>> If CONFIG_X86_X2APIC is undefined and CONFIG_KVM_GUEST is defined,
>>>>> there are undefined reference warning for x2apic_mode and check_x2apic
>>>>> etc since they are extern variables and just define under
>>>>> CONFIG_X86_X2APIC.
>>>>
>>
>> This results in undefined reference warning.
>>
>>>>
>>>>>
>>>>> If -cpu host,-x2apic we should go through mmio when writes xapic EOI.
>>>>
>>>> Any ideas? :)
>>>
>>> Make apic_set_eoi_write return the old pointer?
>>
>> Could you elaborate? :)
>
> No, that won't work due to how struct apic works and how
> apic_set_eoi_write patches it.  One possibility then is to add a
>
>         void (*native_eoi_write)(u32 reg, u32 v);
>
> field to struct apic, and make apic_set_eoi_write set
>
>         (*drv)->native_eoi_write = (*drv)->eoi_write;
>         (*drv)->eoi_write = eoi_write;
>
> Then kvm.c can call
>
>         apic->native_eoi_write(reg, v);

It works. Thanks Paolo. :)

Regards,
Wanpeng Li

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[PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-14 03:50 +0200
  [tip:x86/urgent] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() tip-bot for Wanpeng Li <tipbot@zytor.com> - 2016-10-14 14:30 +0200
  Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Peter Zijlstra <peterz@infradead.org> - 2016-10-16 15:40 +0200
    Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-17 06:30 +0200
      Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Peter Zijlstra <peterz@infradead.org> - 2016-10-17 10:30 +0200
        Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-17 11:50 +0200
          Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Paolo Bonzini <pbonzini@redhat.com> - 2016-10-17 12:20 +0200
            Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-17 12:30 +0200
            Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-18 02:10 +0200
              Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-19 16:20 +0200
                Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-19 16:40 +0200
                Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Paolo Bonzini <pbonzini@redhat.com> - 2016-10-24 16:40 +0200
                Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-25 05:00 +0200
                Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Paolo Bonzini <pbonzini@redhat.com> - 2016-10-19 18:40 +0200
        Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-17 14:20 +0200

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