Re: [RFC PATCH 2/2] arm64: kvm: Introduce MTE VCPU feature

Catalin Marinas
2020-06-17T14:38:20Z

On Wed, Jun 17, 2020 at 01:38:44PM +0100, Steven Price wrote:
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index e3b9ee268823..040a7fffaa93 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -1783,6 +1783,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
> vma_pagesize = PMD_SIZE;
> }
>
> + if (system_supports_mte() && kvm->arch.vcpu_has_mte) {
> + /*
> + * VM will be able to see the page's tags, so we must ensure
> + * they have been initialised.
> + */
> + struct page *page = pfn_to_page(pfn);
> +
> + if (!test_and_set_bit(PG_mte_tagged, &page->flags))
> + mte_clear_page_tags(page_address(page), page_size(page));
> + }

Are all the guest pages always mapped via a Stage 2 fault? It may be
better if we did that via kvm_set_spte_hva().

--
Catalin