Re: [PATCH 1/9] KVM: arm64: Handle huge mappings for np-guest CMOs

Quentin Perret
2025-02-28T18:54:46Z

On Friday 28 Feb 2025 at 10:25:17 (+0000), Vincent Donnefort wrote:
> diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> index 19c3c631708c..a796e257c41f 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -219,14 +219,24 @@ static void guest_s2_put_page(void *addr)
>
> static void clean_dcache_guest_page(void *va, size_t size)
> {
> - __clean_dcache_guest_page(hyp_fixmap_map(__hyp_pa(va)), size);
> - hyp_fixmap_unmap();
> + while (size) {

Nit: not a problem at the moment, but this makes me mildly worried if
size ever became non-page-aligned, could we make the code robust to
that?

> + __clean_dcache_guest_page(hyp_fixmap_map(__hyp_pa(va)),
> + PAGE_SIZE);
> + hyp_fixmap_unmap();
> + va += PAGE_SIZE;
> + size -= PAGE_SIZE;
> + }
> }
>
> static void invalidate_icache_guest_page(void *va, size_t size)
> {
> - __invalidate_icache_guest_page(hyp_fixmap_map(__hyp_pa(va)), size);
> - hyp_fixmap_unmap();
> + while (size) {
> + __invalidate_icache_guest_page(hyp_fixmap_map(__hyp_pa(va)),
> + PAGE_SIZE);
> + hyp_fixmap_unmap();
> + va += PAGE_SIZE;
> + size -= PAGE_SIZE;
> + }
> }
>
> int kvm_guest_prepare_stage2(struct pkvm_hyp_vm *vm, void *pgd)
> --
> 2.48.1.711.g2feabab25a-goog
>