[PATCH v5 18/69] KVM: arm64: nv: Handle virtual EL2 registers in vcpu_read/write_sys_reg()

[Ganapatrao Kulkarni]

On 20-12-2021 02:40 pm, Marc Zyngier wrote:
> On Mon, 20 Dec 2021 07:04:44 +0000,
> Ganapatrao Kulkarni <gankulkarni at os.amperecomputing.com> wrote:
>>
>>
>> On 30-11-2021 01:30 am, Marc Zyngier wrote:
>>> KVM internally uses accessor functions when reading or writing the
>>> guest's system registers. This takes care of accessing either the stored
>>> copy or using the "live" EL1 system registers when the host uses VHE.
>>>
>>> With the introduction of virtual EL2 we add a bunch of EL2 system
>>> registers, which now must also be taken care of:
>>> - If the guest is running in vEL2, and we access an EL1 sysreg, we must
>>>     revert to the stored version of that, and not use the CPU's copy.
>>> - If the guest is running in vEL1, and we access an EL2 sysreg, we must
>>
>> Do we have vEL1? or is it a typo?
> 
> Not a typo, but only a convention (there is no such concept in the
> architecture). vELx denotes the exception level the guest thinks it is
> running at while running at EL1 (as it is the case for both vEL1 and
> vEL2).
> 

OK got it, this is to deal with Non-VHE case.

> Depending on the exception level and the running mode (VHE or not) you
> emulate at any given time, you access the sysregs differently: they
> can be either live in the CPU, stored in memory, with or without
> translation. That's why I'm using these 'parallel' exception levels to
> denote which is which...
> 
> HTH,

Thanks.
> 
> 	M.
> 

Looks good to me, please feel free to add,
Reviewed-by: Ganapatrao Kulkarni <gankulkarni at os.amperecomputing.com>

Thanks,
Ganapat