Messages in this thread | | | Subject | Re: [RFC PATCH 2/2] arm64: kvm: Introduce MTE VCPU feature | From | Steven Price <> | Date | Wed, 17 Jun 2020 16:34:13 +0100 |
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On 17/06/2020 15:38, Catalin Marinas wrote: > 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(). >
I was under the impression that pages are always faulted into the stage 2, but I have to admit I'm not 100% sure about that.
kvm_set_spte_hva() may be more appropriate, although on first look I don't understand how that function deals with huge pages. Is it actually called for normal mappings or only for changes due to the likes of KSM?
Steve
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