Re: [QEMU TCG] Qeustion about the PCID Feature in TCG

[Paolo Bonzini]

On 22/02/21 18:59, Kaifeng Xu wrote:
> Hi,
> Nice to get your replies. I am doing some research which requires me to 
> have some system level memory traces for all memory instructions. I want 
> to use that trace to do some TLB or cache studies.
>
> Actually I don't care if I have the full PCID instruction 
> implementation, I just need to know the PCID of each memory access, in 
> order to do tagged TLB studies.
>
> So I still have 2 questions:
> 1. Can I do this work in KVM mode, i.e. can plugin work in KVM mode?

No.

> 2. Do I need to change anything to get the right PCID? I have seen the 
> PCID field get set in cr3 but I am not sure it's the right one.

I think it's the right one, yes.  It works mostly by chance, but it 
should work for your use case.

Paolo