[PATCH v2 3/3] KVM: arm64: Make ID_AA64MMFR1_EL1.VH writable from userspace

[Jinqian Yang]

On 2025/9/9 13:32, Oliver Upton wrote:
> Hi Jinqian,
> 
> On Tue, Sep 09, 2025 at 11:44:15AM +0800, Jinqian Yang wrote:
>> Allow userspace to downgrade VH in ID_AA64MMFR1_EL1. Userspace can
>> only change this value from high to low.
> 
> I'm afraid we can't allow this. When we expose FEAT_VHE to the VM,
> HCR_EL2.E2H is RES1. Meaning, vEL2 is unconditionally in a VHE
> context.
> 
> I would be OK with a clarifying comment documenting why the field is
> non-writable.
> 

Okay, v3 will keep ID_AA64MMFR1_EL1.VH non-writable.

Thanks,
Jinqian