[PATCH v3 06/13] KVM: arm64: Use LPA2 page-tables for stage2 if HW supports it

[Oliver Upton]

On Mon, Sep 18, 2023 at 07:57:33AM +0100, Ryan Roberts wrote:

[...]

>  static inline u64 kvm_pte_to_phys(kvm_pte_t pte)
>  {
> -	u64 pa = pte & KVM_PTE_ADDR_MASK;
> -
> -	if (PAGE_SHIFT == 16)
> -		pa |= FIELD_GET(KVM_PTE_ADDR_51_48, pte) << 48;
> +	u64 pa;
> +
> +	if (system_supports_lpa2()) {
> +		pa = pte & KVM_PTE_ADDR_MASK_LPA2;
> +		pa |= FIELD_GET(KVM_PTE_ADDR_51_50_LPA2, pte) << 50;
> +	} else {
> +		pa = pte & KVM_PTE_ADDR_MASK;
> +		if (PAGE_SHIFT == 16)
> +			pa |= FIELD_GET(KVM_PTE_ADDR_51_48, pte) << 48;
> +	}
>  
>  	return pa;
>  }
>  
>  static inline kvm_pte_t kvm_phys_to_pte(u64 pa)
>  {
> -	kvm_pte_t pte = pa & KVM_PTE_ADDR_MASK;
> -
> -	if (PAGE_SHIFT == 16) {
> -		pa &= GENMASK(51, 48);
> -		pte |= FIELD_PREP(KVM_PTE_ADDR_51_48, pa >> 48);
> +	kvm_pte_t pte;
> +
> +	if (system_supports_lpa2()) {
> +		pte = pa & KVM_PTE_ADDR_MASK_LPA2;
> +		pa &= GENMASK(51, 50);
> +		pte |= FIELD_PREP(KVM_PTE_ADDR_51_50_LPA2, pa >> 50);
> +	} else {
> +		pte = pa & KVM_PTE_ADDR_MASK;
> +		if (PAGE_SHIFT == 16) {
> +			pa &= GENMASK(51, 48);
> +			pte |= FIELD_PREP(KVM_PTE_ADDR_51_48, pa >> 48);
> +		}
>  	}

These accessors are common between stage-1 and stage-2 walks... Aren't
bits [9:8] of the descriptor still being used to encode shareability for
hyp stage-1 at this point?

You may as well squash the subsequent patch (LPA2 format for S1) into this
one such that the change is atomic.

-- 
Thanks,
Oliver