Re: [PATCH v5 3/6] LoongArch: KVM: Add cpucfg area for kvm hypervisor

[maobibo <maobibo@loongson.cn>]

On 2024/2/27 下午5:05, Xi Ruoyao wrote:
> On Tue, 2024-02-27 at 15:09 +0800, maobibo wrote:
> 
>> It is difficult to find an area unused by HW for CSR method since the
>> small CSR ID range.
> 
> We may use IOCSR instead.  In kernel/cpu-probe.c there are already some
> IOCSR reads.

yes, IOCSR can be used and one IOCSR area will be reserved for software. 
In general CSR/CPUCFG is to describe CPU features and IOCSR is to 
describe board/device features.

CSR area is limited to 16K, it is difficult for HW guys to reserve 
special area for software usage. IOCSR/CPUCFG is possible however.

Regards
Bibo Mao
> 
>> It is difficult to find an area unused by HW for CSR method since the
>> small CSR ID range. However it is easy for cpucfg. Here I doubt whether
>> you really know about LoongArch LVZ.
> 
> It's unfair to accuse the others for not knowing about LVZ considering
> the lack of public documentation.
>