[PATCH v4 02/46] KVM: PPC: Book3S HV: Add a function to filter guest LPCR bits

[Paul Mackerras]

On Tue, Mar 23, 2021 at 11:02:21AM +1000, Nicholas Piggin wrote:
> Guest LPCR depends on hardware type, and future changes will add
> restrictions based on errata and guest MMU mode. Move this logic
> to a common function and use it for the cases where the guest
> wants to update its LPCR (or the LPCR of a nested guest).

[snip]

> @@ -4641,8 +4662,9 @@ void kvmppc_update_lpcr(struct kvm *kvm, unsigned long lpcr, unsigned long mask)
>  		struct kvmppc_vcore *vc = kvm->arch.vcores[i];
>  		if (!vc)
>  			continue;
> +
>  		spin_lock(&vc->lock);
> -		vc->lpcr = (vc->lpcr & ~mask) | lpcr;
> +		vc->lpcr = kvmppc_filter_lpcr_hv(vc, (vc->lpcr & ~mask) | lpcr);

This change seems unnecessary, since kvmppc_update_lpcr is called only
to update MMU configuration bits, not as a result of any action by
userspace or a nested hypervisor.  It's also beyond the scope of what
was mentioned in the commit message.

Paul.