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Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1ljMDk-00FV7A-9l for linux-arm-kernel@lists.infradead.org; Wed, 19 May 2021 13:26:45 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 799E731B; Wed, 19 May 2021 06:26:43 -0700 (PDT) Received: from [192.168.1.179] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F1AF63F73B; Wed, 19 May 2021 06:26:40 -0700 (PDT) Subject: Re: [PATCH v12 6/8] arm64: kvm: Expose KVM_ARM_CAP_MTE To: Marc Zyngier Cc: Catalin Marinas , Will Deacon , James Morse , Julien Thierry , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave Martin , Mark Rutland , Thomas Gleixner , qemu-devel@nongnu.org, Juan Quintela , "Dr. David Alan Gilbert" , Richard Henderson , Peter Maydell , Haibo Xu , Andrew Jones References: <20210517123239.8025-1-steven.price@arm.com> <20210517123239.8025-7-steven.price@arm.com> <87tun1tg1l.wl-maz@kernel.org> From: Steven Price Message-ID: <4e1fc7b7-ea8c-a87c-9177-d9e03ff96cb8@arm.com> Date: Wed, 19 May 2021 14:26:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87tun1tg1l.wl-maz@kernel.org> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210519_062644_418335_D4705155 X-CRM114-Status: GOOD ( 16.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 17/05/2021 18:40, Marc Zyngier wrote: > On Mon, 17 May 2021 13:32:37 +0100, > Steven Price 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 >> --- >> 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. Indeed, however the MTE flag is a property of the VM not of the vCPU. And, unless I'm mistaken, it's technically possible to create a VM where some CPUs are 32 bit and some 64 bit. Not that I can see much use of a configuration like that. Steve _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel