Re: [RFC PATCH 09/12] target/arm/cpu: Add CPU cache description for arm

[Ying Fang]

On 9/17/2020 4:39 PM, Andrew Jones wrote:
> On Thu, Sep 17, 2020 at 11:20:30AM +0800, Ying Fang wrote:
> > Add the CPUCacheInfo structure to hold CPU cache information for ARM cpus.
> > A classic three level cache topology is used here. The default cache
> > capacity is given and userspace can overwrite these values.
>
> Doesn't TCG already have some sort of fake cache hierarchy? If so, then

TCG may have some sort of fake cache hierarchy via CCSIDR.

> we shouldn't be adding another one, we should be simply describing the
> one we already have. For KVM, we shouldn't describe anything other than
> what is actually on the host.

Yes, I agreed. Cache capacity should be the with host otherwise it may
have bad impact on guest performance, we can do that by query from the
host and make cache capacity configurable from userspace.

Dario Faggioli is going to give a talk about it in KVM forum [1].

[1] 
https://kvmforum2020.sched.com/event/eE1y/virtual-topology-for-virtual-machines-friend-or-foe-dario-faggioli-suse?iframe=no&w=100%&sidebar=yes&bg=no

Thanks.

> drew
>
> .