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Tue, 27 Jul 2021 08:59:28 -0700 (PDT) Received: from [192.168.0.110] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C5A6A3F70D; Tue, 27 Jul 2021 08:59:26 -0700 (PDT) Subject: Re: [PATCH v2 3/6] KVM: arm64: Avoid mapping size adjustment on permission fault To: Marc Zyngier , linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-mm@kvack.org References: <20210726153552.1535838-1-maz@kernel.org> <20210726153552.1535838-4-maz@kernel.org> From: Alexandru Elisei Message-ID: <5216fbb0-1df2-325c-5e4d-98245c7470e6@arm.com> Date: Tue, 27 Jul 2021 17:00:37 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210726153552.1535838-4-maz@kernel.org> Content-Language: en-US Cc: kernel-team@android.com, Sean Christopherson , Matthew Wilcox , Paolo Bonzini , Will Deacon X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Marc, On 7/26/21 4:35 PM, Marc Zyngier wrote: > Since we only support PMD-sized mappings for THP, getting > a permission fault on a level that results in a mapping > being larger than PAGE_SIZE is a sure indication that we have > already upgraded our mapping to a PMD. > > In this case, there is no need to try and parse userspace page > tables, as the fault information already tells us everything. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/kvm/mmu.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 0adc1617c557..ebb28dd4f2c9 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1076,9 +1076,14 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > * If we are not forced to use page mapping, check if we are > * backed by a THP and thus use block mapping if possible. > */ > - if (vma_pagesize == PAGE_SIZE && !(force_pte || device)) > - vma_pagesize = transparent_hugepage_adjust(kvm, memslot, hva, > - &pfn, &fault_ipa); > + if (vma_pagesize == PAGE_SIZE && !(force_pte || device)) { > + if (fault_status == FSC_PERM && fault_granule > PAGE_SIZE) > + vma_pagesize = fault_granule; > + else > + vma_pagesize = transparent_hugepage_adjust(kvm, memslot, > + hva, &pfn, > + &fault_ipa); > + } Looks good: Reviewed-by: Alexandru Elisei Thanks, Alex > > if (fault_status != FSC_PERM && !device && kvm_has_mte(kvm)) { > /* Check the VMM hasn't introduced a new VM_SHARED VMA */ _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm