Re: [PATCH v12 6/8] arm64: kvm: Expose KVM_ARM_CAP_MTE

From: Marc Zyngier <maz@kernel.org>
To: Steven Price <steven.price@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Andrew Jones <drjones@redhat.com>, Haibo Xu <Haibo.Xu@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	qemu-devel@nongnu.org, Catalin Marinas <catalin.marinas@arm.com>,
	Juan Quintela <quintela@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	linux-kernel@vger.kernel.org, Dave Martin <Dave.Martin@arm.com>,
	James Morse <james.morse@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu,
	Julien Thierry <julien.thierry.kdev@gmail.com>
Subject: Re: [PATCH v12 6/8] arm64: kvm: Expose KVM_ARM_CAP_MTE
Date: Mon, 17 May 2021 18:40:22 +0100	[thread overview]
Message-ID: <87tun1tg1l.wl-maz@kernel.org> (raw)
In-Reply-To: <20210517123239.8025-7-steven.price@arm.com>

On Mon, 17 May 2021 13:32:37 +0100,
Steven Price <steven.price@arm.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@arm.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.