kvm VMCALL question

kvm VMCALL question

[jack.chen]

hello ,I execute VMCALL in virtual machine，But no vm exit occured,is
the VMCALL need set some bit in register or VMCS ??
thanks!
#define VMCALL_M __asm _EMIT 0x0f __asm _EMIT 0x01 __asm _EMIT 0xc1

Fwd: kvm VMCALL question

[jack.chen]

---------- Forwarded message ----------
From: jack.chen <zhunxun@gmail.com>
Date: 2016-12-30 17:14 GMT+08:00
Subject: kvm VMCALL question
To: KVM maillist <kvm@vger.kernel.org>


hello ,I execute VMCALL in virtual machine，But no vm exit occured,is
the VMCALL need set some bit in register or VMCS ??
thanks!
#define VMCALL_M __asm _EMIT 0x0f __asm _EMIT 0x01 __asm _EMIT 0xc1
Can any one  help me???
thanks!!!

Re: kvm VMCALL question

[Paolo Bonzini]

On 30/12/2016 10:14, jack.chen wrote:
> hello ,I execute VMCALL in virtual machine，But no vm exit occured,is
> the VMCALL need set some bit in register or VMCS ??
> thanks!
> #define VMCALL_M __asm _EMIT 0x0f __asm _EMIT 0x01 __asm _EMIT 0xc1

If you're expecting an exit to QEMU, you won't get it; VMCALL is usually
handled entirely in the kernel.

Paolo

Re: kvm VMCALL question

[jack.chen]

thanks, I just need it exit to kvm ,however every time I execute
VMCALL,it program breakdown,and no exit occured!!I do not know why!

2017-01-02 17:55 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
> Please reply to the mailing list, or I will stop answering your
> questions even there.
>
> Paolo
>
> On 02/01/2017 10:48, jack.chen wrote:
>> thanks, I just need it exit to kvm ,however every time I execute
>> VMCALL,it program breakdown,and no exit occured!!I do not know why!
>>
>> 2017-01-02 17:36 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>>>
>>>
>>> On 30/12/2016 10:14, jack.chen wrote:
>>>> hello ,I execute VMCALL in virtual machine，But no vm exit occured,is
>>>> the VMCALL need set some bit in register or VMCS ??
>>>> thanks!
>>>> #define VMCALL_M __asm _EMIT 0x0f __asm _EMIT 0x01 __asm _EMIT 0xc1
>>>
>>> If you're expecting an exit to QEMU, you won't get it; VMCALL is usually
>>> handled entirely in the kernel.
>>>
>>> Paolo

Re: kvm VMCALL question

[jack.chen]

  Thanks,it is my fault that I ignore
 if (kvm_hv_hypercall_enabled(vcpu->kvm))
return kvm_hv_hypercall(vcpu);
in the kvm_emulate_hypercall function,and in fact VM exit did occured!
however,I have another question,I want to set PF_VECTOR in exception
and to intercept a specific address in VM such as 0xFFFFFFFF,at fist I
set PAGE_FAULT_ERROR_CODE_MASK and PAGE_FAULT_ERROR_CODE_MATCH to 0
,so as to get my target error code,then change
PAGE_FAULT_ERROR_CODE_MASK fitting my error code,but at the first
step,host break down!I do not know why!
can you analyse the possible reason??
thanks a lot!

2017-01-03 19:47 GMT+08:00 Huaitong Han <oenhan@gmail.com>:
> how did you confirm no VM-Exit occurred
>
> Thanks.
>
> Huaitong Han
> Intel OTC Virtualization team
>
> 2017-01-02 18:24 GMT+08:00 jack.chen <zhunxun@gmail.com>:
>>
>> thanks, I just need it exit to kvm ,however every time I execute
>> VMCALL,it program breakdown,and no exit occured!!I do not know why!
>>
>> 2017-01-02 17:55 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>> > Please reply to the mailing list, or I will stop answering your
>> > questions even there.
>> >
>> > Paolo
>> >
>> > On 02/01/2017 10:48, jack.chen wrote:
>> >> thanks, I just need it exit to kvm ,however every time I execute
>> >> VMCALL,it program breakdown,and no exit occured!!I do not know why!
>> >>
>> >> 2017-01-02 17:36 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>> >>>
>> >>>
>> >>> On 30/12/2016 10:14, jack.chen wrote:
>> >>>> hello ,I execute VMCALL in virtual machine，But no vm exit occured,is
>> >>>> the VMCALL need set some bit in register or VMCS ??
>> >>>> thanks!
>> >>>> #define VMCALL_M __asm _EMIT 0x0f __asm _EMIT 0x01 __asm _EMIT 0xc1
>> >>>
>> >>> If you're expecting an exit to QEMU, you won't get it; VMCALL is
>> >>> usually
>> >>> handled entirely in the kernel.
>> >>>
>> >>> Paolo
>> --
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>
>