From patchwork Fri Jun 18 13:28:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Price X-Patchwork-Id: 12331427 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5D8C7C48BE8 for ; Fri, 18 Jun 2021 13:33:53 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 200FC60FE5 for ; Fri, 18 Jun 2021 13:33:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 200FC60FE5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=XOoCbXFBlAg6l616sgy3uDu/fHoPYCeOMfjJTHSAv7w=; b=JSViyMKY9iNZH2 Fh2HLHbKJHnTMd9t85+CxyvzSgUJZQsDeTEi0wdBbb7W0pGkYhIu84d6aK1GWHcTaUpaAAcEpQtMr +1kGPv9cT9NP2EJPAFlSMKjj18lEwPrWykVZdQFE3xyY0VsNmW3bfoZC1MBETKI+e1Gpn61gMuT6l 9w0rHMJbdDXrODoryPM3t3URf/pJ+D9fJkdSbrqWXITAX3mg+h9QN4CgVQObJkrdB0hYu3dF7vwa6 oWeCGh5vq87wXJqDGwvjZLmZtCsGPayyZAu3ws2hbwnpIw93Y40+CiyWclZsDub49zd4dl995uKnD 9dj5H9whepT3bqP+2Ouw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1luEbL-00EG85-IJ; Fri, 18 Jun 2021 13:32:04 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1luEYN-00EEuI-NQ for linux-arm-kernel@lists.infradead.org; Fri, 18 Jun 2021 13:29:01 +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 1E1E11424; Fri, 18 Jun 2021 06:28:58 -0700 (PDT) Received: from e112269-lin.arm.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 738C23F719; Fri, 18 Jun 2021 06:28:55 -0700 (PDT) From: Steven Price To: Catalin Marinas , Marc Zyngier , Will Deacon Cc: Steven Price , 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 , Andrew Jones Subject: [PATCH v16 7/7] KVM: arm64: Document MTE capability and ioctl Date: Fri, 18 Jun 2021 14:28:26 +0100 Message-Id: <20210618132826.54670-8-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210618132826.54670-1-steven.price@arm.com> References: <20210618132826.54670-1-steven.price@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210618_062859_958590_D4E5562A X-CRM114-Status: GOOD ( 16.17 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 Reviewed-by: Catalin Marinas --- Documentation/virt/kvm/api.rst | 61 ++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 22d077562149..3c27e712b1fb 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -5034,6 +5034,43 @@ see KVM_XEN_VCPU_SET_ATTR above. The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used with the KVM_XEN_VCPU_GET_ATTR ioctl. +4.130 KVM_ARM_MTE_COPY_TAGS +--------------------------- + +:Capability: KVM_CAP_ARM_MTE +:Architectures: arm64 +:Type: vm ioctl +:Parameters: struct kvm_arm_copy_mte_tags +:Returns: number of bytes copied, < 0 on error (-EINVAL for incorrect + arguments, -EFAULT if memory cannot be accessed). + +:: + + struct kvm_arm_copy_mte_tags { + __u64 guest_ipa; + __u64 length; + void __user *addr; + __u64 flags; + __u64 reserved[2]; + }; + +Copies Memory Tagging Extension (MTE) tags to/from guest tag memory. The +``guest_ipa`` and ``length`` fields must be ``PAGE_SIZE`` aligned. The ``addr`` +field must point to a buffer which the tags will be copied to or from. + +``flags`` specifies the direction of copy, either ``KVM_ARM_TAGS_TO_GUEST`` or +``KVM_ARM_TAGS_FROM_GUEST``. + +The size of the buffer to store the tags is ``(length / 16)`` bytes +(granules in MTE are 16 bytes long). Each byte contains a single tag +value. This matches the format of ``PTRACE_PEEKMTETAGS`` and +``PTRACE_POKEMTETAGS``. + +If an error occurs before any data is copied then a negative error code is +returned. If some tags have been copied before an error occurs then the number +of bytes successfully copied is returned. If the call completes successfully +then ``length`` is returned. + 5. The kvm_run structure ======================== @@ -6362,6 +6399,30 @@ default. See Documentation/x86/sgx/2.Kernel-internals.rst for more details. +7.26 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 the +VMM before creating any VCPUs to allow the guest access. Note that MTE is only +available to a guest running in AArch64 mode and enabling this capability will +cause attempts to create AArch32 VCPUs to fail. + +When enabled the guest is able to access tags associated with any memory given +to the guest. KVM will ensure that the tags are maintained during swap or +hibernation of the host; however the VMM needs to manually save/restore the +tags as appropriate if the VM is migrated. + +When this capability is enabled all memory in (non-device) memslots must not +used VM_SHARED, attempts to create a memslot with a VM_SHARED mmap will result +in an -EINVAL return. + +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. ======================