From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29BF3C00449 for ; Wed, 3 Oct 2018 16:26:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EBE8721470 for ; Wed, 3 Oct 2018 16:26:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EBE8721470 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727234AbeJCXPH (ORCPT ); Wed, 3 Oct 2018 19:15:07 -0400 Received: from foss.arm.com ([217.140.101.70]:53602 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726811AbeJCXPH (ORCPT ); Wed, 3 Oct 2018 19:15:07 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8FB0980D; Wed, 3 Oct 2018 09:26:01 -0700 (PDT) Received: from localhost (e105922-lin.Emea.Arm.com [10.4.13.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 243FB3F5D3; Wed, 3 Oct 2018 09:26:00 -0700 (PDT) From: Punit Agrawal To: Marc Zyngier Cc: kvmarm@lists.cs.columbia.edu, will.deacon@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v8 2/9] KVM: arm/arm64: Share common code in user_mem_abort() References: <20181001155443.23032-1-punit.agrawal@arm.com> <20181001155443.23032-3-punit.agrawal@arm.com> <1eb4df93-4610-ac83-fec3-6a7efeddfc4f@arm.com> Date: Wed, 03 Oct 2018 17:25:59 +0100 In-Reply-To: <1eb4df93-4610-ac83-fec3-6a7efeddfc4f@arm.com> (Marc Zyngier's message of "Wed, 3 Oct 2018 16:20:39 +0100") Message-ID: <87o9cbhu94.fsf@e105922-lin.cambridge.arm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Marc Zyngier writes: > Hi Punit, > > On 01/10/18 16:54, Punit Agrawal wrote: >> The code for operations such as marking the pfn as dirty, and >> dcache/icache maintenance during stage 2 fault handling is duplicated >> between normal pages and PMD hugepages. >> >> Instead of creating another copy of the operations when we introduce >> PUD hugepages, let's share them across the different pagesizes. >> >> Signed-off-by: Punit Agrawal >> Cc: Suzuki K Poulose >> Cc: Christoffer Dall >> Cc: Marc Zyngier >> --- >> virt/kvm/arm/mmu.c | 45 +++++++++++++++++++++++++++++---------------- >> 1 file changed, 29 insertions(+), 16 deletions(-) >> >> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c >> index c23a1b323aad..5b76ee204000 100644 >> --- a/virt/kvm/arm/mmu.c >> +++ b/virt/kvm/arm/mmu.c >> @@ -1490,7 +1490,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, >> kvm_pfn_t pfn; >> pgprot_t mem_type = PAGE_S2; >> bool logging_active = memslot_is_logging(memslot); >> - unsigned long flags = 0; >> + unsigned long vma_pagesize, flags = 0; >> write_fault = kvm_is_write_fault(vcpu); >> exec_fault = kvm_vcpu_trap_is_iabt(vcpu); >> @@ -1510,10 +1510,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, >> return -EFAULT; >> } >> - if (vma_kernel_pagesize(vma) == PMD_SIZE && !logging_active) { >> + vma_pagesize = vma_kernel_pagesize(vma); >> + if (vma_pagesize == PMD_SIZE && !logging_active) { >> hugetlb = true; >> gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT; >> } else { >> + /* >> + * Fallback to PTE if it's not one of the Stage 2 >> + * supported hugepage sizes >> + */ >> + vma_pagesize = PAGE_SIZE; >> + >> /* >> * Pages belonging to memslots that don't have the same >> * alignment for userspace and IPA cannot be mapped using >> @@ -1579,23 +1586,34 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, >> if (mmu_notifier_retry(kvm, mmu_seq)) >> goto out_unlock; >> - if (!hugetlb && !force_pte) >> + if (!hugetlb && !force_pte) { >> + /* >> + * Only PMD_SIZE transparent hugepages(THP) are >> + * currently supported. This code will need to be >> + * updated to support other THP sizes. >> + */ >> hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa); >> + if (hugetlb) >> + vma_pagesize = PMD_SIZE; >> + } >> + >> + if (writable) >> + kvm_set_pfn_dirty(pfn); >> - if (hugetlb) { >> + if (fault_status != FSC_PERM) >> + clean_dcache_guest_page(pfn, vma_pagesize); >> + >> + if (exec_fault) >> + invalidate_icache_guest_page(pfn, vma_pagesize); >> + >> + if (hugetlb && vma_pagesize == PMD_SIZE) { > > Can you end-up in a situation where hugetlb==false and vma_pagesize == > PMD_SIZE? If that's the case, then the above CMOs are not done on the > same granularity as they were done before this patch. If that cannot > happen, then the above condition can be simplified. > > Which one is it? hugetlb is a hangover from when we didn't have vma_pagesize. I think we can drop it and rely on the pagesize to control the size of mapping we put down. Let me give that a try. Thanks for taking a look. > > > Thanks, > > M.