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

[Catalin Marinas]

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