From: Alexandru Elisei <alexandru.elisei@arm.com>
To: Marc Zyngier <maz@kernel.org>,
linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
kvmarm@lists.cs.columbia.edu, linux-mm@kvack.org
Cc: Sean Christopherson <seanjc@google.com>,
Matthew Wilcox <willy@infradead.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Will Deacon <will@kernel.org>,
Quentin Perret <qperret@google.com>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
kernel-team@android.com
Subject: Re: [PATCH v2 3/6] KVM: arm64: Avoid mapping size adjustment on permission fault
Date: Tue, 27 Jul 2021 17:00:37 +0100 [thread overview]
Message-ID: <5216fbb0-1df2-325c-5e4d-98245c7470e6@arm.com> (raw)
In-Reply-To: <20210726153552.1535838-4-maz@kernel.org>
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 <maz@kernel.org>
> ---
> 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 <alexandru.elisei@arm.com>
Thanks,
Alex
>
> if (fault_status != FSC_PERM && !device && kvm_has_mte(kvm)) {
> /* Check the VMM hasn't introduced a new VM_SHARED VMA */
next prev parent reply other threads:[~2021-07-27 15:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 15:35 [PATCH v2 0/6] KVM: Remove kvm_is_transparent_hugepage() and friends Marc Zyngier
2021-07-26 15:35 ` [PATCH v2 1/6] KVM: arm64: Introduce helper to retrieve a PTE and its level Marc Zyngier
2021-07-27 10:29 ` Quentin Perret
2021-07-27 15:25 ` Alexandru Elisei
2021-07-28 12:17 ` Marc Zyngier
2021-07-26 15:35 ` [PATCH v2 2/6] KVM: arm64: Walk userspace page tables to compute the THP mapping size Marc Zyngier
2021-07-27 15:55 ` Alexandru Elisei
2021-07-26 15:35 ` [PATCH v2 3/6] KVM: arm64: Avoid mapping size adjustment on permission fault Marc Zyngier
2021-07-27 16:00 ` Alexandru Elisei [this message]
2021-07-26 15:35 ` [PATCH v2 4/6] KVM: Remove kvm_is_transparent_hugepage() and PageTransCompoundMap() Marc Zyngier
2021-07-26 15:35 ` [PATCH v2 5/6] KVM: arm64: Use get_page() instead of kvm_get_pfn() Marc Zyngier
2021-07-27 17:46 ` Alexandru Elisei
2021-07-26 15:35 ` [PATCH v2 6/6] KVM: Get rid " Marc Zyngier
2021-08-02 13:39 ` [PATCH v2 0/6] KVM: Remove kvm_is_transparent_hugepage() and friends Marc Zyngier
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