From: Marc Zyngier <maz@kernel.org>
To: Peter Collingbourne <pcc@google.com>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, Cornelia Huck <cohuck@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Evgenii Stepanov <eugenis@google.com>,
kvm@vger.kernel.org, Steven Price <steven.price@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>
Subject: Re: [PATCH v3 6/7] KVM: arm64: permit all VM_MTE_ALLOWED mappings with MTE enabled
Date: Mon, 12 Sep 2022 17:23:16 +0100 [thread overview]
Message-ID: <874jxcv9xn.wl-maz@kernel.org> (raw)
In-Reply-To: <20220810193033.1090251-7-pcc@google.com>
On Wed, 10 Aug 2022 20:30:32 +0100,
Peter Collingbourne <pcc@google.com> wrote:
>
> Certain VMMs such as crosvm have features (e.g. sandboxing) that depend
> on being able to map guest memory as MAP_SHARED. The current restriction
> on sharing MAP_SHARED pages with the guest is preventing the use of
> those features with MTE. Now that the races between tasks concurrently
> clearing tags on the same page have been fixed, remove this restriction.
>
> Signed-off-by: Peter Collingbourne <pcc@google.com>
> ---
> arch/arm64/kvm/mmu.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index d54be80e31dd..fc65dc20655d 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1075,14 +1075,6 @@ static void sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn,
>
> static bool kvm_vma_mte_allowed(struct vm_area_struct *vma)
> {
> - /*
> - * VM_SHARED mappings are not allowed with MTE to avoid races
> - * when updating the PG_mte_tagged page flag, see
> - * sanitise_mte_tags for more details.
> - */
> - if (vma->vm_flags & VM_SHARED)
> - return false;
> -
> return vma->vm_flags & VM_MTE_ALLOWED;
> }
>
Can you provide a pointer to some VMM making use of this functionality
and enabling MTE? A set of crosvm patches (for example) would be
useful to evaluate this series.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2022-09-12 16:27 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-10 19:30 [PATCH v3 0/7] KVM: arm64: permit MAP_SHARED mappings with MTE enabled Peter Collingbourne
2022-08-10 19:30 ` [PATCH v3 1/7] arm64: mte: Fix/clarify the PG_mte_tagged semantics Peter Collingbourne
2022-09-01 15:49 ` Catalin Marinas
2022-09-02 10:26 ` Cornelia Huck
2022-09-02 14:47 ` Steven Price
2022-08-10 19:30 ` [PATCH v3 2/7] KVM: arm64: Simplify the sanitise_mte_tags() logic Peter Collingbourne
2022-09-02 14:47 ` Steven Price
2022-08-10 19:30 ` [PATCH v3 3/7] mm: Add PG_arch_3 page flag Peter Collingbourne
2022-08-11 7:16 ` kernel test robot
2022-09-01 17:59 ` Catalin Marinas
2022-09-05 17:01 ` Catalin Marinas
2022-09-19 18:12 ` Marc Zyngier
2022-09-20 15:39 ` Catalin Marinas
2022-09-20 16:33 ` Marc Zyngier
2022-09-20 16:58 ` Catalin Marinas
2022-09-21 3:53 ` Peter Collingbourne
2022-08-10 19:30 ` [PATCH v3 4/7] arm64: mte: Lock a page for MTE tag initialisation Peter Collingbourne
2022-09-02 14:47 ` Steven Price
2022-09-02 16:28 ` Catalin Marinas
2022-09-02 16:58 ` Catalin Marinas
2022-09-05 7:37 ` Steven Price
2022-08-10 19:30 ` [PATCH v3 5/7] KVM: arm64: unify the tests for VMAs in memslots when MTE is enabled Peter Collingbourne
2022-09-02 13:41 ` Catalin Marinas
2022-09-02 14:47 ` Steven Price
2022-08-10 19:30 ` [PATCH v3 6/7] KVM: arm64: permit all VM_MTE_ALLOWED mappings with MTE enabled Peter Collingbourne
2022-09-02 13:45 ` Catalin Marinas
2022-09-02 14:47 ` Steven Price
2022-09-12 16:23 ` Marc Zyngier [this message]
2022-09-13 4:10 ` Peter Collingbourne
2022-08-10 19:30 ` [PATCH v3 7/7] Documentation: document the ABI changes for KVM_CAP_ARM_MTE Peter Collingbourne
2022-09-02 13:49 ` Catalin Marinas
2022-09-02 14:05 ` [PATCH v3 0/7] KVM: arm64: permit MAP_SHARED mappings with MTE enabled Catalin Marinas
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