Re: [patch 2/4] KVM: MMU: allow pinning spte translations (TDP-only)

[Nadav Amit <nadav.amit@gmail.com>]

Small question if I may regarding kvm_mmu_pin_pages:

On 7/9/14, 10:12 PM, mtosatti@redhat.com wrote:
> +
> +static int kvm_mmu_pin_pages(struct kvm_vcpu *vcpu)
> +{
> +	struct kvm_pinned_page_range *p;
> +	int r = 1;
> +
> +	if (is_guest_mode(vcpu))
> +		return r;
> +
> +	if (!vcpu->arch.mmu.direct_map)
> +		return r;
> +
> +	ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
> +
> +	list_for_each_entry(p, &vcpu->arch.pinned_mmu_pages, link) {
> +		gfn_t gfn_offset;
> +
> +		for (gfn_offset = 0; gfn_offset < p->npages; gfn_offset++) {
> +			gfn_t gfn = p->base_gfn + gfn_offset;
> +			int r;
> +			bool pinned = false;
> +
> +			r = vcpu->arch.mmu.page_fault(vcpu, gfn << PAGE_SHIFT,
> +						     PFERR_WRITE_MASK, false,
> +						     true, &pinned);

I understand that the current use-case is for pinning only few pages. 
Yet, wouldn't it be better (for performance) to check whether the gfn 
uses a large page and if so to skip forward, increasing gfn_offset to 
point to the next large page?

Thanks,
Nadav