From nobody Tue Feb 10 06:58:07 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=arm.com ARC-Seal: i=1; a=rsa-sha256; t=1614610274; cv=none; d=zohomail.com; s=zohoarc; b=mEwpcet6cfcrmRggpTA91RZ8gxkDX/zGn7g9omHc9ySxE+DoZGEmDDWAP8ElSSHWdbMQjeH3t5au9XeO7nolEJvCl9pcFeOX0OXdtFEBamlD/jKzWICPBiyqpdwzGGJMXeE3+h/ojjS65H0N2oWj5M20JO5tkXGjXF32UNCQTXw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1614610274; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=fQXtUglvKm+CEooqZyO9tHltVcL+pPIoZ/xesPCs2FA=; b=OAv5D52ieCPTa0nyrmaFeaD+nN/mq9U7tVKsG68gbHFpBjzhjm15DOd3T5ZV7TFODrHesi31MScz/D6m009pfTvUldbP1/yZq98NSclr/PY+APsX4JHDV/bJvKTwFcG7kQLyD22u2on2ZSVuhpRQuL/zUOnu/kSRydl4YUXSkiM= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1614610274811633.7050404242591; Mon, 1 Mar 2021 06:51:14 -0800 (PST) Received: from localhost ([::1]:52048 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lGjtB-0003bb-JB for importer@patchew.org; Mon, 01 Mar 2021 09:51:13 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41928) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lGjSm-0002ZY-CF for qemu-devel@nongnu.org; Mon, 01 Mar 2021 09:23:57 -0500 Received: from foss.arm.com ([217.140.110.172]:51724) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lGjSi-0004vn-C1 for qemu-devel@nongnu.org; Mon, 01 Mar 2021 09:23:55 -0500 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 4D1B61396; Mon, 1 Mar 2021 06:23:51 -0800 (PST) Received: from e112269-lin.arm.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8D7D13F70D; Mon, 1 Mar 2021 06:23:48 -0800 (PST) From: Steven Price To: Catalin Marinas , Marc Zyngier , Will Deacon Subject: [PATCH v9 6/6] KVM: arm64: Document MTE capability and ioctl Date: Mon, 1 Mar 2021 14:23:15 +0000 Message-Id: <20210301142315.30920-7-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210301142315.30920-1-steven.price@arm.com> References: <20210301142315.30920-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=217.140.110.172; envelope-from=steven.price@arm.com; helo=foss.arm.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Peter Maydell , "Dr. David Alan Gilbert" , Andrew Jones , Haibo Xu , Suzuki K Poulose , qemu-devel@nongnu.org, Dave Martin , Juan Quintela , Richard Henderson , linux-kernel@vger.kernel.org, Steven Price , James Morse , Julien Thierry , Thomas Gleixner , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" A new capability (KVM_CAP_ARM_MTE) identifies that the kernel supports granting a guest access to the tags, and provides a mechanism for the VMM to enable it. A new ioctl (KVM_ARM_MTE_COPY_TAGS) provides a simple way for a VMM to access the tags of a guest without having to maintain a PROT_MTE mapping in userspace. The above capability gates access to the ioctl. Signed-off-by: Steven Price --- Documentation/virt/kvm/api.rst | 37 ++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index aed52b0fc16e..1406ea138127 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -4939,6 +4939,23 @@ KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO Allows Xen vCPU attributes to be read. For the structure and types, see KVM_XEN_VCPU_SET_ATTR above. =20 +4.131 KVM_ARM_MTE_COPY_TAGS +--------------------------- + +:Capability: KVM_CAP_ARM_MTE +:Architectures: arm64 +:Type: vm ioctl +:Parameters: struct kvm_arm_copy_mte_tags +:Returns: 0 on success, < 0 on error + +Copies Memory Tagging Extension (MTE) tags to/from guest tag memory. The +starting address and length of guest memory must be ``PAGE_SIZE`` aligned. + +The size of the buffer to store the tags is ``(length / MTE_GRANULE_SIZE)`` +bytes (i.e. 1/16th of the corresponding size). Each byte contains a single= tag +value. This matches the format of ``PTRACE_PEEKMTETAGS`` and +``PTRACE_POKEMTETAGS``. + 5. The kvm_run structure =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 @@ -6227,6 +6244,25 @@ KVM_RUN_BUS_LOCK flag is used to distinguish between= them. This capability can be used to check / enable 2nd DAWR feature provided by POWER10 processor. =20 +7.23 KVM_CAP_ARM_MTE +-------------------- + +:Architectures: arm64 +:Parameters: none + +This capability indicates that KVM (and the hardware) supports exposing the +Memory Tagging Extensions (MTE) to the guest. It must also be enabled by t= he +VMM before the guest will be granted access. + +When enabled the guest is able to access tags associated with any memory g= iven +to the guest. KVM will ensure that the pages are flagged ``PG_mte_tagged``= so +that the tags are maintained during swap or hibernation of the host, howev= er +the VMM needs to manually save/restore the tags as appropriate if the VM is +migrated. + +When enabled the VMM may make use of the ``KVM_ARM_MTE_COPY_TAGS`` ioctl to +perform a bulk copy of tags to/from the guest + 8. Other capabilities. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 @@ -6716,3 +6752,4 @@ KVM_XEN_HVM_SET_ATTR, KVM_XEN_HVM_GET_ATTR, KVM_XEN_V= CPU_SET_ATTR and KVM_XEN_VCPU_GET_ATTR ioctls, as well as the delivery of exception vectors for event channel upcalls when the evtchn_upcall_pending field of a vcpu's vcpu_info is set. + --=20 2.20.1