linux-kernel - Re: [PATCH v12 6/8] arm64: kvm: Expose KVM_ARM_CAP

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Message-ID: <87tun1tg1l.wl-maz@kernel.org>
Date:   Mon, 17 May 2021 18:40:22 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Steven Price <steven.price@....com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Dave Martin <Dave.Martin@....com>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Gleixner <tglx@...utronix.de>, qemu-devel@...gnu.org,
        Juan Quintela <quintela@...hat.com>,
        "Dr. David Alan Gilbert" <dgilbert@...hat.com>,
        Richard Henderson <richard.henderson@...aro.org>,
        Peter Maydell <peter.maydell@...aro.org>,
        Haibo Xu <Haibo.Xu@....com>, Andrew Jones <drjones@...hat.com>
Subject: Re: [PATCH v12 6/8] arm64: kvm: Expose KVM_ARM_CAP_MTE

On Mon, 17 May 2021 13:32:37 +0100,
Steven Price <steven.price@....com> wrote:
> 
> It's now safe for the VMM to enable MTE in a guest, so expose the
> capability to user space.
> 
> Signed-off-by: Steven Price <steven.price@....com>
> ---
>  arch/arm64/kvm/arm.c      | 9 +++++++++
>  arch/arm64/kvm/sys_regs.c | 3 +++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 1cb39c0803a4..e89a5e275e25 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -93,6 +93,12 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
>  		r = 0;
>  		kvm->arch.return_nisv_io_abort_to_user = true;
>  		break;
> +	case KVM_CAP_ARM_MTE:
> +		if (!system_supports_mte() || kvm->created_vcpus)
> +			return -EINVAL;
> +		r = 0;
> +		kvm->arch.mte_enabled = true;

As far as I can tell from the architecture, this isn't valid for a
32bit guest.

	M.

-- 
Without deviation from the norm, progress is not possible.